Back to Home   Antenna Systems Information
(antennas, feedlines, duplexers, circulators, isolators, calculators, etc.)
Compiled by Mike Morris WA6ILQ
Maintained by Robert Meister WA1MIK
   


Note that the contents of this page, like most here at www.repeater-
builder.com, are totally dependent on donations of information.

If you have something to share please consider writing it up and sending it in.

If you have relevant data sheets, class handouts or any other information that we do not have here, please consider scanning them and emailing us the scans.


Jump to:   System Engineering     Antennas     Towers     Cavities, Duplexers and Diplexers     Combiners
  Feedline, Coax, Connectors and Shielding     Isolators and Circulators     Calculators
  Mobile     Home Brew


Below is a Google ad (to help pay the bandwidth and hosting bill).   No endorsement of the products is implied.

Just in case you are trying to locate some documentation...

Phelps-Dodge (also known as PD) was bought by Celwave (year?), which was bought by Radio Frequency Systems (aka RFS) (year?) whose web site is at http://www.rfsworld.com/RFSGlobal. If you are looking for other web pages containing information on a specific antenna - for example some repeater group whose web page mentions a Phelps-DodgePD-458 in passing - you may have to check under all three company names. For example, under Google, you would type (less the square brackets): [ "PhelpsDodge" OR Celwave OR "Radio Frequency Systems" OR "RFS" 458 ]. Note that the OR parameter in a Google search must be in ALL CAPS.

MFJ bought Hy-gain in May of 1999. Then they purchased Cushcraft in August of the same year.

Antenna Specialists was sold to PCTel (year?) - and their corporate web site is at http://www.antenna.com, and the product web site is at http://www.antenna.com.

I was told recently that PCTel bought both Maxrad and Antennex (but I don't know the dates).

DB Products was bought by Andrew, but they didn't want everything. The leftovers (including duplexers) are now sold by a company called dbSpectra, located in Lewisville, Texas (the web site is at http://www.dbspectra.com). From their web site: "...in December of 2004, dbSpectra signed a licensing agreement with Andrew Corporation to manufacture and sell the Legacy Decibel Products site management equipment such as filters, duplexers, combiners, tower top amplifiers and more. These products had been outsourced and dbSpectra successfully brought them back and have since hired many of the personnel involved in the design and manufacture of these excellent products."

In March of 2006 the Laird Group of England (AKA LairdTech) purchased Antenex for about $20.5 million, and then in Febuary of 2007 bought Cushcraft for about $90 million.

And about a month later Andrew purchased the English manufacturer Precision Antennas for about $36 million.

In December of 2007 Andrew was bought by CommScope for US$2.6 Billion. Here's the current Commscope home page. They seem to have integrated the Andrew products into their own offerings.


In many cases you will find that manufacturers web sites have theoretical information that is applicable to all... i.e. the theory articles on Manufacturer "X" products applies to Manufacturer "Y" and to "Z". Sometimes researching other manufacturers web sites can save you a lot of money... for example, if Manufacturer "X" claims that a crystal filter will solve your desense problem. Then you go to "Y"s web site and there you discover that, yes, a crystal filter can be used in the receiver feedline to notch out a local signal, or to pass your signal. What the Manufacturer "X" web site didn't tell you, and the Manufacturer "Y " or "Z" web site did, is that in your specific case it may not work. Unless you were familiar with crystal filters you would not know that the insertion loss can be as high as 12db, which in many cases makes a crystal filter on a repeater receiver unusable.... the signal level budget just isn't there (i.e. while adding the crystal filter would kill the interfering signal, it also reduced your receiving range to 1/2 of what it was, or maybe even less). So do your homework and learn all you can about the theory behind the hardware before you hand over your money.


System Engineering

Introductory Information for System Engineering   READ THIS FIRST
Getting the most from your repeater system   By Kevin Custer W3KKC
RF Communications - A Non Technical Approach   1.47 MB PDF By Decibel Products Corp.
Many years ago Decibel Products (a major RF hardware manufacturer) published a series of informative pamphlets on systems engineering topics. The earliest seems to be 1964. The topics included Base Station Antennas, Combiners, Selective Cavities, Duplexers, RF Transmission Lines and Lightning. All five pamphlets were recently combined into a single PDF document titled "RF Communications - A Non-Technical Approach". DB made it available on their corporate web site, and it's available as a 1.2 MB local copy here. This document should be required reading for anyone wanting to learn about antenna systems. (Thanks to Duane Hall KA8GVH for the pointer.)
TX-RX Tech Aid #77001   Some very useful charts and procedures. Worth printing and adding to your tech notebook. 767 kB PDF By TX-RX Corp.
Help!! My repeater seems deaf   By Kevin K. Custer W3KKC
Repeater Sensitivity De-sense Testing   325 kB PDF by Jacques Audet VE2AZX
An excellent writeup that explains the techniques plus shows how to build a high-isolation signal sampler.
Receiver desense testing   By Karl Shoemaker AK2O of the Spokane Repeater Group     (Original offsite link at the SRG web site)
Is a 3 dB change in power really worth it?   The answer is "It Depends"   By Neil Johnson WBØEMU
If you are in charge of maintaining a repeater system, or building a new one, then this is worth reading.
Some thoughts on Repeater Receiver-to-Transmitter Isolation   By Mike Morris WA6ILQ
Guidelines for mounting antennas on towers   71 kB PDF. A scan of a guidelines page covering tower-to-antenna distances - donated by Skipp
ANTPLOT - A Side-Tower Mounted Antenna Pattern Prediction Program   This is a Zip file of both version 5.3 and of version 5.4 of the DOS program originally provided by Antenna Specialists. It's noted as being "Program No. 3 of the Antenna Specialists RF TOOLS Series". Also called "tplot" for some reason.
Does anyone have Program #1, #2 and any others?
Recommended Coax and Connectors for the iDEN Enhanced Base Transceiver System   24 kB PDF. Motorola Engineering wrote this three page discussion of cable and connector types with regard to combining, intermodulation, and other RF performace factors. They concluded that LMR-nnn and LMR-nnnn series cable is specifically NOT recommended in any radio site RF environments, especially duplex environments (where NNN is any 3-digit number and NNNN is any 4 digit number). While iDEN is (was?) a 900 MHz system the physics are the same at 28 MHz through 1296 MHz. Well worth reading.
HELIAX Coaxial Cable for Low Intermodulation Generation   21 kB PDF. Andrew Engineering wrote this one page writeup on why foil-braid cable causes intermod. Despite the fact that you'd expect that conclusion from the makers of Heliax there's a lot less sales pitch and a lot more engineering presented than you'd think. Worth reading.
Where exactly is your repeater?   And are you really sure? Read this before you file any paperwork and help out your local coordination folks, and prevent an FCC or FAA citation. Donated by Eric Lemmon WB6FLY
MIL-STD-188-124B "Grounding, Bonding, and Shielding for Common Long Haul/Tactical Communication Systems including Ground Based Communications-Electronics Facilities and Equipments"   3.8 MB PDF file dated 01-Feb-92
This is the newer military handbook on grounding, and is a quicker read at about 40 pages, however it says on the second page of the forward that "This Standard is further implemented by MIL-HDBK-419", listed below. This handbook is approved for public release and distribution is unlimited.
MIL-HDBK-419A "Grounding, Bonding, and Shielding for Electronic Equipments and Facilities"   9.6 MB PDF file dated 29-DEC-1987
This is the big military handbook on grounding. It is large, in two volumes totaling about 812 pages. Volume one is 396 pages of theory, volume two is 394 pages of practice. This download is the complete 2 volume set in one PDF file, and volume 2 starts on page 419 of the PDF file. This book covers grounding for safety, lightning, nuclear blast and most everything else. A very good read and a real eye opener. This handbook is approved for public release and distribution is unlimited.
At one point (Feb 1999), the hardcopy (including postage) was FREE if you ordered it from:
Commanding Officer
Naval Publication and Forms Center
5801 Taylor Avenue
Philladelphia PA 19120
MIL-STD-464 "Department of Defense Interface Standard Electromagnetic Environmental Effects Requirements for Systems"   1.2 MB PDF file dated 18-Mar-97
"This standard establishes electromagnetic environmental effects (E3) requirements and verification criteria for airborne, sea, space, and ground systems, including associated ordnance." This handbook is approved for public release and distribution is unlimited.
Why, you might ask, is this one on a web page that covers antenna systems? Well, "electromagnetic environmental effects" includes lightning. And lightning can have seriously negative effects on antenna systems (and the radios they are connected to).
More lightning info is here (offsite link), on the IEEE web site, including several links to other excellent IEEE articles.
High power amplifiers and duplex radio   Tubes vs. Transistors,   By Kevin Custer W3KKC   Short version: at high power levels tubes win.
Is this connector any good?   An article on the perils of cheap connectors by Jeff DePolo WN3A
EMR Corp. Technical Papers Index   An index of downloadable PDF papers on Isolators, Duplexer retuning, Ferrite and Hybrid Combiners, Multicouplers, Preselectors, Bandpass and Pass-Notch Cavity Resonators.
Using Preamps with repeaters... and why sometimes you wouldn't want to... by Mark Malm NØFAZ and Kevin K. Custer W3KKC
The Effects of Trees on Slant Propagation Paths   1.3 MB PDF By Vogel Hagn. This is an academic paper that will be of special interest to UHF, 900 and 1200 MHz system owners.
Best Practices Guide   49 kB PDF By Motorola Inc. This is a write up on solving interference problems at 800 MHz and oriented towards Public Safety communications, but it's worth reading by any repeater owner or builder.
Interference Technical Appendix   682 kB PDF By Motorola Inc. This is intended to be an add-on to the "Best Practices Guide" above. Also very worth reading.
Calculating Your Radio Horizon
Radio Mobile   Coverage prediction software by Roger Coudé VE2DBE   A bit of a learning curve, but darn good stuff (offsite link)
A Yahoo group supporting it is at http://groups.yahoo.com/group/Radio_Mobile_Deluxe   If anybody wants to put together a "Getting Started" article, we'll make room for it here.
The calculators, especially Dale Bickel's HAAT, Coordinate and Distance calculators are useful. Scroll down to the Calculators section for them.


Combiners

Introductory Information about Combiners   READ THIS FIRST
About Combiners   511 kB PDF By DB Products, copyrighted 1975.
From the preface: "This booklet has been written for the many people engaged in two-way radio communications who are NOT radio engineers. A non-technical presentation of a rather complex subject has been attempted in an effort to bring about a better understanding of combiners used in two-way radio systems."
Tuning Instructions for the DB-4350 and DB-4360 Low Loss Combiners   8 kB PDF file.
Tuning Procedure for Two-Transmitter Combiners DB-4351, DB-4381, DB-4352, DB-4382, DB-4384
Two page 65 kB PDF describing the tuneup of a unit that is essentially two isolators, two low pass filters, a hybrid coupler and a dummy load.
Product Description and Installation and Tuning Instructions for the ACT27nnJ2 and DBNXTL27nn Transmitter Combiner   8 kB PDF PDF file.
5-Channel Models: ACT2705J2, DBNXTL2705
10-Channel Models: ACT2710J2, DBNXTL2710
15-Channel Model: ACT2715J2
20-Channel Model: ACT2720J2
Tuning Instructions for the DB-4379 Low Loss Combiner   9 kB PDF file describing a unit for up to 8 transmitters.
Celwave 220 brochure   580 kB PDF
Back when 220-222 was stolen from the hams to be a new land mobile radio band Celwave put together a brochure with the tech specs on all of their 220 products plus three sample system diagrams.
The products include the PD220-8, PD220DT, 92.0101, and 93.0024 antennas, the TJD220-5T transmitter combiner, PD1604B cavity, PD5042-2 duplexer, PD5279 cavity, PD5280-1, PD5280-2 and PD5280-3 duplexers, PD1602 low-pass filter, PD506-2A duplexer, PD5091-2A dual notch cavity, PD5090-2B/3 bandpass filter and the PD5090-2A bandpass cavity.
Speaking of home-made cavities...   114 kB PDF. What does this have to do with Combiners? A combiner has cavities as part of the unit... And this article is a description of a low cost combiner system (as many as 27 transmitters on one antenna) that started with beer barrels.


Isolators and Circulators

Introductory Information for Isolators and Circulators   READ THIS FIRST
If circulators and isolators are a new topic to you, I suggest that you read the first four articles in this section, especially the one by William F. Lieske. Yes, there is some repeated material between the articles, but if you're new to the topic, it won't hurt. When you have multiple people writing on the same topic some repetition is inevitable.
What's a circulator? a.k.a. Properties of a Ferromagnetic Circulator   By Kevin Custer W3KKC
The Care and Feeding of the RF Isolator   a 118 kB PDF by William F. Lieske, Sr. Founder, EMR Corporation
An Elementary Introduction to Ferrite Isolators, Circulators and RF Loads   a 1 MB PDF file by TX-RX Corp. "Seminar Series" writeup - 14 pages.
Circulators and Ring Hybrids   a 363 kB PDF by Wolfgang Borschel DK2DO
Field Tuning Instructions for Dual Junction Tunable Isolators   a 21 kB PDF file by Decibel Products
Generic single stage / single-section isolator tuning instructions from EMR   a 26 kB PDF file donated by Eric Lemmon WB6FLY
Generic dual stage / dual section isolator tuning instructions from EMR   a 55 kB PDF file donated by Eric Lemmon WB6FLY
Sinclair's instructions on tuning isolators   144 kB PDF Donated by Eric Lemmon WB6FLY
Microwave Associates 7R011 and 7R021 Isolator Tuning Instructions   65 kB PDF Donated by Micheal Salem N5MS
Good for 125 watts, with 0.9 dB insertion loss typical with 1.3 dB max. The isolation can be as high as 60 dB with 50 dB typical.
Data sheet on the DB-4318H-2C High Band Single Channel filter and isolator
A 9 kB PDF file describing a Decibel Products 164-168.5 MHz dual isolator but the directions apply to similar units. The drawing is in error, it does not show the termination (a Bird Termaline) on the output port.


Cavities, Diplexers, Duplexers, Theory, and More

Introductory Information on Cavities, Diplexers, and Duplexers   READ THIS FIRST
If you're just starting out, I strongly suggest that you read the above article, then first nine articles in this section, especially those by Jacques Audet VE2AZX, John Portune W6NBC and by William F. Lieske. Yes, there is some repeated material between the articles, but if you're new to duplexers, it won't hurt. The 9 articles collectively will give you a basic and solid education on duplexers.
About Duplexers   5.3 MB PDF By DB Products, copyrighted 1970.
From the preface: "This booklet has been written for the many people engaged in two-way radio communications who are NOT radio engineers. A non-technical presentation of a rather complex subject has been attempted in an effort to bring about a better understanding of duplexers used in two-way radio systems."
DUPLEXERS - An Introductory Tutorial   by Jack Daniel KD6YVL     (offsite link)
This is a nice writeup that should be titled "Duplexers 101". Well worth reading.
Theory and Testing of Duplexers   1.4 MB PDF by Jacques Audet VE2AZX
This is a large (60 pages) technical writeup that should be titled "Duplexers 102". Again, well worth reading.
Technical Duplexer Page with good theory and explanations, and some homebrew construction notes. By John Portune W6NBC
Understanding, Maintaining and Re-Tuning Antenna Duplexers   145 kB PDF By William F. Lieske, Sr., Founder of EMR Corporation
A good basic theory writeup, including the differences between Band Pass and Band Reject.
Combating Spurious Output And Overloading With Cavity Filters   a 1.2 MB PDF by TX-RX Corp.
A "Seminar Series" writeup that covers the theory behind cavity filters - mandatory reading for those unfamiliar with them.
Coaxial Resonators, Applied theory and practice, with photos   by Mike Pinfold ZL1BTB (offsite link)
Duplexer Theory and Tuning   351 kB PDF by Dave Metz WAØAUQ
An overview of duplexers from an amateurs point of view, with some good hands-on info and some photos of a good home-brew duplexer.
Why are there quarter-wave coax cables between my duplexer's cavities?   Gary Schafer K4FMX
This article also explains why the fully-cabled duplexer provides more notch depth than the sum of the separate sections.
Interference Control Through The Use Of Cavity Filters And Ferrite Isolators   a 900 kB PDF by TX-RX Corp.
Technical Notes on Duplexer Problems and Remedies   a 1 MB PDF by TX-RX Corp.
The Design of High Isolation Duplexers and A New Antenna for Duplex Systems   772 kB PDF
An IEEE Transactions publication from March 1965 by W. B. Bryson of Communications Products Company, a division of Phelps Dodge.
A Guide to Duplexer Specifications   over 130 different models, by Paul Kelley N1BUG (Contributions to the list are very welcome)
Tuning and Adjusting Vari-Notch-Duplexers   a 185 kB PDF by TX-RX Corp.
A "Seminar Series" writeup that covers the theory behind cavity filters and isolators.
T-Pass Expandable Cavity Muticoupler System   a 500 kB PDF by TX-RX Corp.
A "Seminar Series" writeup that covers the various type of cavity-based multicouplers and the T-Pass design.
The Hybrid Ring Duplexer   A comprehensive explanation of the Hybrid Ring, by Kevin Custer W3KKC
Six Meter Heliax Duplexer Design   by Jim Poll WB5WPA (web page is gone)
Here's one implementation of the above design   by Oscar Quintanilla KF6YB (offsite link)
Here's another implementation of the above design   by Mike Perryman K5JMP (offsite link)
Six Meter Heliax Receive Filter Construction and Testing article based on the above designs, by Robert Meister WA1MIK and David Malicki N1OFJ. Note that this is NOT a full duplexer; just the receive half (but it could easily be extended to a full duplexer).
Yet another implementation of a six meter filter   by Tim Ahrens W5FN
Another Heliax notch filter, but for two meters   by Jeff Otterson N1KDO.
Some Tests on Duplexer Loops   233 kB PDF   by Jacques Audet VE2AZX
Some interesting observations, including scope traces.
GE Datafile Bulletin 10002-1, A 25-250 MC Quarter Wave Stub Filter   General Electric produced several useful RF engineering DataFile Bulletins (the ones we have are available for free download from the GE LBI page at this web site). This one is a 400 kB PDF file, and is subtitled:
"Even though General Electric Two Way Radio Transmitters well exceed FCC requirements for spurious radiation, the 60-80-dB sprious attenuation provided may, in a few situations, be insufficicient to provent interference. This bulletin describes the construction of a filter, useful for supressing spurious radiation at one specific frequency..."
Someone say 6 meter duplexer?   A comprehensive conversion of a lowband pass cavity to BpBr by Jeff DePolo WN3A...
How do I tune this notch duplexer?   by Kevin Custer W3KKC
Tests of the DCI VHF and UHF 4-pole bandpass filters   by Robert W. Meister WA1MIK
These filters definitely do the job, meeting or exceeding manufacturer's specs. They cover the entire 144-148 and 440-450 MHz bands and have sharp cutoffs. If you need more filtering, they also sell 6, 8, and 10-pole filters with attenuations over 80dB. These handle 200 watts and can be used at repeater sites.
A Homemade Duplexer for 2-Meter Repeaters   820 kB PDF By John Bilodeau, W1GAN (from the July 1972 QST magazine)
Note: In the 35-plus years since this article was written, the spring-contact based BNC has fallen out of favor. Type N connectors (and to a lesser extent the TNC connector) are much preferred over BNC connectors as they depend on a silver-to-silver screw compression contact, plus they can handle more power. You must use double shielded coax in the harness. RG-55 is mentioned in the article, but I'd use RG-400 and compensate on the inter-cavity lengths. If anybody has built this unit with better connectors and modern cable, and would like to update this article please do so, then write an article we can put here.
Speaking of home-made cavities...   114 kB PDF. This writeup shows what can be accomplished with aluminum beer barrels.
Speaking of home-made duplexers...   This photo shows what can be accomplished with old fire extinguishers.
Garbage In, No Garbage Out   2.5 MB PDF file By John E. Portune, W6NBC from the July 1996 issue of 73 Magazine.
John needed a cavity to protect his 137 MHz weather satelite receiver system from local grunge - and discovered that a common metal garbage can made a good starting point.
Homebrew Diplexer Design Notes   22 kB PDF file by unknown.
Some hand-written design notes for making a simple 144/440 MHz diplexer.

RFS / Celwave   See also Phelps-Dodge, as Celwave bought that company and continued many of their products under the Celwave name. Click here for Celwave antennas
  RFS 633-6A-2N Duplexer Catalog / Specification Sheet   99 kB PDF file
  RFS 633-6A-5N Duplexer Catalog / Specification Sheet   138 kB PDF file
  Celwave model 696, 696SR (UHF), 896 or 896SR (800-960 MHz) Duplexer   185 kB PDF file Donated by Allan Crites WA9ZZU, scanned by Eric Lemmon WB6FLY
  Celwave Duplexer Cable Harness Lengths (oriented for printing)   46 kB PDF file
  Celwave 220 brochure   580 kB PDF
Back when 220-222 was stolen from the hams to be a new land mobile radio band Celwave put together a brochure with the tech specs on all of their 220 products plus three sample system diagrams.
The products include the PD220-8, PD220DT, 92.0101, and 93.0024 antennas, the TJD220-5T transmitter combiner, PD1604B cavity, PD5042-2 duplexer, PD5279 cavity, PD5280-1, PD5280-2 and PD5280-3 duplexers, PD1602 low-pass filter, PD506-2A duplexer, PD5091-2A dual notch cavity, PD5090-2B/3 bandpass filter and the PD5090-2A bandpass cavity.

Decibel Products   Click here for DB antennas
Note that Decibel Products ("DB") and Phelps Dodge ("PD") used similar model numbers at times. A DB-506 is very different from a PD506...
  Data Sheet on DB's line of power dividers - Three page 268 kB PDF file donated by John Lock KFØM
This writeup covers the K522 and K542 for 144-174 MHz, the K526 and K546 for 406-512 MHz, the K528 and K548 for 800-960 MHz and the K528M and K548M for 1850-1990 MHz
  DB's pipe and tower mounting clamp kit DB-365-OS   Early version donated by John Lock KFØM
  DB's pipe and tower mounting clamp kit DB-365-OS and ASPR616   165 kB PDF file (later version)
  Catalog pages for early model DB-4002 band pass cavities   740 kB PDF file
The 4002 cavity covers multiple ranges, the cavity is the same, the differences are in the loops. A=118-148 MHz, B=144-174 MHz, C=406-420 MHz, D=450-512 MHz.
  Installation and Tuning Instructions for DB Band Pass Cavity Filters   50 kB PDF file
This information is pretty generic despite the models listed: DB-4001 (148-174 MHz), DB-4002 (118-512 MHz), DB-4011 (70-88 MHz), DB-4013 (88-118 MHz), DB-4015 (118-148 MHz), DB-4020 (406-420 MHz), DB-4018 (225-400 MHz), DB-4021 (406-512 MHz), DB-4026 (406-512 MHz), DB-4028 (806-960 MHz), DB-4042 (30-50 MHz), DB-4170 (138-174 MHz), DB-4171 (450-512 MHz).
  Tuning Instructions for the DB-4022 (UHF) and 4029 (800 MHz) band pass / band reject cavities   32 kB PDF file
  DB-4023 UHF duplexer (3 cavity) and 4081 (4 cavity) spec sheet   donated by W. M. Kahl N6KYD
  Tuning Instructions for the DB-4030 (four cavity) and 4032 (six cavity) Low Band Duplexers   five page 920 kB PDF donated by W. M. Kahl N6KYD
    Tuning Instructions for the DB-4030 and 4032 4-cavity and 6-cavity Low Band Duplexers   24 kB PDF file (appears to be a later version of the five page one above)
    Converting the DB-4032 Low Band Duplexer to the 6M Amateur Band   29 kB image   A one-page writeup from DB Engineering on converting the DB-4032 to the6-meter amateur band. It's a scan of a fax so it's not perfect, but it's quite readable (oriented for printing)
Same drawing sized to be printed on 11x17 paper   Both donated by Chris Nicholson N9LLO
  Installation and Alignment Instructions for the DB-4036 (mid-band), 4044 and 4046 (high-band) Base Station Duplexers   48 kB PDF file
A two-page PDF file describing wide-spaced (3 MHz and 5 MHz) duplexers that are not of much use to hams, but would be to public safety and disaster services folks.
  DB-4042 Resonant Filter Modifications   An offsite link to KB6MIP's Technical Information Page articles.
  DB-4048 duplexer specs (high band - 146-174 MHz) - an eight page 1.22 MB PDF file
    DB-4048 duplexer review article from June 1975 QST magazine -   Page 1   Page 2   Scan courtesy of Glenn Little WB4UIV
  Modifying/Improving the DB-4048 Notch Cavity Duplexer By Ralph Hogan W4XE
  Installation and Tuning Instructions for the DB-4055 and 4056 (high band), 4067 and 4068 (406-420 UHF) and 4071 and 4072 (450-470 UHF) duplexers   A two-page 41 kB PDF file
        Here's a photo of the internals of a 4072 housing.
  Installation and Tuning on Decibel Products 4057 (three cavity) and 4058 (four cavity) high band duplexers   Two page 123 kB PDF file
  Catalog sheet on the DB-4060 and 4062 Band Pass/Band Reject duplexers   55 kB PDF file
    Installation and Tuning Instructions for the DB-4060 and 4062 Band Pass / Band Reject duplexers   46 kB PDF file (the DB-4060 has 4 cavities, the 4062 has 6 cavities)
    Repair of the DB-4060 and 4062 Band Pass / Band Reject duplexers   344 kB   An article by Bernie K5BP detailing notch capacitor replacement for these units, including a source for the original component.
    Repair of the DB-4060 and 4062 Band Pass/Band Reject duplexers   An offsite web page by N1BUG... he writes:
I have a DB-4062, which is the 6 cavity version of the 4060. It was old when I placed it in service in 1997 but worked OK. Over the years it just slowly deteriorated until it became essentially unusable. Finally I took the thing apart to investigate, and was able to restore it to excellent function after 15-20 hours of work. I created a web page that covered my experience...
Specifications and Data on the DB-4075 and DB-4076 UHF Bandpass Reject duplexers   423 kB PDF file Photo
Wiring Diagram for the DB-4076 UHF Bandpass Reject duplexer shown in the above photo   28 kB PDF file
  Tuning and Installation Information on the DB-4075 and DB-4076 UHF Bandpass Reject duplexers   91 kB PDF file
  Tuning Information on the DB-4090 806-960 MHz Bandpass Reject duplexers   44 kB PDF file
  Installation and Tuning Instructions for the DB-4104 (low band), 4040 (high band) and4075 (UHF) single-cavity notch filters   25 kB PDF file
  Installation and Tuning Instructions for the 4307, 4308 and 4309 Hybrid Couplers   14 kB PDF file
  Installation and Tuning Instructions for the DB-4318H-2C Single Channel Filter and Isolator   10 kB PDF file describing a 164-168.5 MHz unit but the directions apply to similar units.

Motorola
Note that over the years Motorola house-labeled many products made by Antenna Specialists, DB, PD, and others. If anyone has a translation list or chart (even just a few model numbers) we'd love to offer it here.
Info on the T1480 series high band 4-can duplexer / cavity filter panel   953 kB PDF file of the official Moto manual that covers the two-cavity and four-cavity models (T1481, T1482, T1485A, T1485AF, T1487A, T1487AF)
Info on the T1500 series UHF 4-can duplexer / cavity filter panel   There's quite a bit of info, so it has its own web page that covers the T1500, T1501, T1502, T1503, T1504, T1505, T1506 and T1507 units.
Info on the T4084A, T4085A, T5002A series UHF 4-can duplexer   547 kB PDF file of the manual scanned by KØDAN.
If anyone has any experience or tech info related to the Motorola TU313 series of low band cavities we'd appreciate it.

Phelps-Dodge
Note that Phelps Dodge ("PD") and Decibel Products ("DB") used similar model numbers at times. A PD-506 is very different from a DB-506...
PD-497 duplexer manual   1.2 MB PDF file
PD-506 manual   263 kB PDF   Donated by Allan Crites WA9ZZU, scanned by Eric Lemmon WB6FLY
NOTE: You CANNOT tell from the model number if a PD-506 is for 144-174 or for 220-225 MHz ! You have to look at the frequency label !
This is a 4-cavity pass-notch duplexer than is supplied as either a 144-174 or 220-225 MHz version. At high band it will work from 600 KHz to 7 MHz separation, and at 220 it will work at from 1 to 5 MHz separation. Rejection is specified at 80 dB, and under 2 dB insertion loss.
PD-506 duplexer manual   75 kB PDF file cleaned and PDF'd by WA1MIK
PD-522-509 manual   1.1 MB PDF Donated by Bill Hudson W6CBS
The manual says Celwave as they bought Phelps-Dodge, and this particular manual was printed after the purchase.
Does anyone have the factory spec sheet or catalog sheet, the tuning instructions or can supply a couple of photos?
PD-526-509 manual   492 kB PDF   UHF pass/reject duplexer courtesy of Joe Szczech K1IKE.
    Photo 1     Photo 2
Eric Lemmon WB6FLY wrote: This is a 6 Cavity UHF Repeater and Base Station Duplexer that is an outstanding performer.
Specs:
    Frequency Coverage = 435 to 470 MHz.
    Minimum Frequency Spacing = 3 MHz.
    Minimum TX to RX Isolation = 100 dB
    Maximum Insertion Loss = 1.0 dB
    TX Bandwidth = 0.025 MHz.
    RX Bandwidth = 0.025 MHz.
    Maximum Power Input = 250 watts
    Connectors = "N" Female
    Maximum VSWR (50 ohms) = 1.3:1
This duplexer is also sold by Motorola as part number 0185417U05, which has a current (mid 2009) dealer price of $ 1,173.00. It is made for Motorola by RFS/Celwave, which sells the same unit as PD526-4-2. It is the X182AD Option for Quantar, Quantro, and MTR2000 stations. I have an identical unit in service on a 100 watt UHF MTR2000 repeater, and it is an excellent performer. Prior to installation, I verified that its isolation was better than the 120 dB specified- a very good figure.
PD-638-509-6 manual   263 kB PDF   Donated by Allan Crites WA9ZZU, scanned by Eric Lemmon WB6FLY
This is a 6-cavity pass-notch mobile duplexer that is available as a 150-162, 162-174, 220-225, or 471-512 MHz unit.
- 150-162 or 162-174 MHz: 150 watts, 75dB rejection, 1.2 dB insertion loss at 2 MHz spacing. At 5 MHz the insertion loss drops to 0.7 dB.
- 220-225 MHz: 100 watts, 75dB rejection, 2 dB insertion loss at 1.6 MHz spacing.
- 470-512 MHz: 75 watts, 75dB rejection, 1.7 dB insertion loss at 3 MHz spacing.
PD-5042-1 VHF Duplexer data from Motorola   960 kB PDF   scanned by Eric Lemmon WB6FLY
Motorola relabels the Celwave model PD5042-1-50 duplexers and includes them as factory option with VHF Quantar or MTR2000 stations. Their part numbers are 0185417U01 for the 132-146 MHz range, 0185417U02 covers 144-160 MHz, and 0185417U03 covers 158-174 MHz.
PD-7540, PD-7560, PD-7640, PD-7660 duplexer manual   109 kB   This unit is also called the "MiniPlexer".
This is a UHF flat-pack mobile notch-only duplexer that is limited to 40 watts and comes in two ranges: 406-435 and 435-470 MHz and in 4 can or 6-can versions (7n40=4-can, 7n60=6-can). The 4-can version provides 50 dB rejection and 1 dB insertion loss at 5 MHz spacing, and the 6-can version provides 75 dB and 1.3 dB. Like any notch-only duplexer, any frequency outside the notches rides right through.
PD-7540, PD-7560, PD-7640, PD-7660 duplexer manual   518 Kb
This is a later verion of the same manual, with enough new information to be worth having both versions available. Donated by Allan Crites WA9ZZU, scanned by Eric Lemmon WB6FLY.

Sinclair Labs
Sinclair's literature is inconsistent on the model number layout. Some has a dash/hyphen (like in "Q-202G"), while some doesn't. If you are searching for something try the search both ways.
P-Series Duplexer Specifications Sheet   Covering the P-1C01-G, P-1C02G, P-201G, P202G, P203G, P-301G, P-302G, P-303G models   418 kB PDF by Sinclair Corporation.
Q202G Series Duplexer Specifications Sheet   233 kB PDF by Sinclair Corporation.
Sinclair Q202-G cable harness drawing   88 kB courtesy of Eric Lemmon WB6FLY
Eric wrote in an email: A while back I set up a Q-202G duplexer for a local radio club. The duplexer was originally made for and used on a commercial pair in the 152-157 MHz band, and no matter how much work was spent on tinung the duplexer it would not perform. I had the club purchase a new low-split harness from Sinclair. When it arrived, I took careful measurements of both the new and the old harness, and the results are here... If the harness on your duplexer is the high-split version, with about 12 inches between tee centers, you will never be able to achieve optimum peformance on 2m, especially in the 145 repeater range. Some people "stretch" the cables by adding 90 degree elbow adapters to the ends as a test, but while that works you will eventually end up buying or making a new harness. The factory-made harness uses Delta brand crimped connectors, and is priced in the area of $250.
Eric continued with "If I were to do this again, I would consider fabricating the harness myself, with genuine Delta brand connectors and tees, which can be purchased for a total of around $120".
If you do, don't forget to use real mil-spec RG-214 or RG-393 coax with the silver plating (look up "duplex noise" and "LMR-400" elsewhere at this web site).
Tuning instructions for "P" and "Q" series cavity duplexers, and FP, FR, FQ series cavities   417 kB PDF by Sinclair Corporation.
Tuning instructions for the Q-202G, Q-208G, Q-218G, 2B02G, Q-2B02G, Q-2B17G series cavity duplexers   1.06 MB PDF by Sinclair Corporation.
Catalog sheet and Specifications for the 6 cavity Res-Lock Q-Circuit VHF Duplexer   355 kB PDF
Tuning instructions for the Q-Series, ResLok 4 - Q‑circuit Duplexers   1.3 MB PDF
Written on the front is "Sincl Q2330E"
Installation and Tuning instructions for the Q‑Circuit Res-Lock Duplexers   217 kB PDF
This manual covers the Q-1220E (66‑88 MHz), Q-2220E (132‑174 MHz), Q-2222E (148‑174 MHz), Q-3220E (406‑512 MHz) and Q-4220E (806‑960 MHz) duplexers.
Photos of a new coupling loop for a 2220E: Photo 1     Photo 2     Photo 3     Photo 4
Duplexer Tuning Instructions for the R101G to R116G and R-1C01-G, R-1C02G, R-1A01G models   869 kB PDF
Note: This manual also covers a large number of other models in the 2H-30, 2H-37, 2H-43, 2H-66, 2H-77, H-30, H-37, H-43, H-66 and H-77 series. The actual list is on the first page.
Modification of R101, R104, or R110 for amateur 6 meter operation   976 kB PDF
Hybrid Ring Duplexer Tuning Instructions   (manual CM-106) (theory on the W2EUP-designed Sinclair Hybrid Ring Duplexer).
VHF Hybrid Ring Duplexer Spec Sheet   70 pB PDF Courtesy of Matt Krick K3MK
For F101, F201, F202, F207 models.
MR-354, MR-356 and MR-3332 406-512 MHz mobile duplexer catalog sheet   191 kB JPG file - scan of a catalog page.
Mobile duplexer MR-354 Specification Sheet   2-page 88 kB PDF file donated by Ted Maczulat VE7TFM
Mobile duplexer MR-356 Specification Sheet   2-page 87 kB PDF file
MR series mobile duplexer tuning   150 kB PDF
Covers the MR-254 and MR-256 (high band, 4.5-10MHz separation), MR-354 and MR-356 (UHF, 5-10MHz separation), MR-454 and MR-456 (806-952 MHz, up to 45 MHz separation) units. Note that these duplexers are rated at 50 watts or less. The high band units are built for either 148-160 MHz or 160-174 MHz splits, the UHF are built for either the 406-450 MHz or 440-512 MHz splits, and the 800/900 units are built for 806-890 MHz and 928-952 MHz splits.
SRL-101C Low band antenna information   The sheet says "30-50 MHz" but gives info on 30-90 MHz. 440 kB PDF file.
SRL-229 High band antenna information
Epoxy Procedure   167 kB PDF
Base Pipe   61 kB PDF
Installation Instructions   143 kB PDF
Mounting Detail   92 kB PDF
"FP", "FR", "FQ" Series Bandpass Filters Product Description   Page 1 34 kB     Page 2 29 kB     Donated by Eric Lemmon WB6FLY.
"FP" Series Electrical Specs 27 kB PDF file donated by Eric Lemmon WB6FLY (undated)
"FR" Series Electrical Specs 31 kB PDF file donated by Eric Lemmon WB6FLY (undated)
"FQ" Series Electrical Specs 30 kB PDF file donated by Eric Lemmon WB6FLY (undated)
"FP" Series Tuning 61 kB PDF file donated by Eric Lemmon WB6FLY
"FR"Series Tuning 68 kB PDF file donated by Eric Lemmon WB6FLY
"FQ"Series Tuning 71 kB PDF file donated by Eric Lemmon WB6FLY
"FP","FR", "FQ" Series Parts 23 kB PDF file donated by EricLemmon WB6FLY
"FP", "FR", "FQ" Series Tuning 48 kB PDF file donated by Eric Lemmon WB6FLY (undated)
"FP", "FR", "FQ" Series Tuning   2.64 MB PDF dated August 2010
"P","Q", "R" Series Description 37 kB PDF file donated byEric Lemmon WB6FLY
"P" Series Electrical Specs 40 kB PDF file donated by Eric Lemmon WB6FLY
"Q" Series Electrical Specs 41 kB PDF file donated by Eric Lemmon WB6FLY
"P" and "Q" Series Preliminary Tuning 32 kB PDF file donated by Eric Lemmon WB6FLY
"P" and "Q" Series Outlines 42 kB PDF file donated by Eric Lemmon WB6FLY
"P" Series Retuning 58 kB PDF file donated by Eric Lemmon WB6FLY
"Q" Series Tuning 86 kB PDF file donated by Eric Lemmon WB6FLY
"P" and "Q" Series Parts 33 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Description 53 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Systems 79 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Electrical Specs 59 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Mechanical Specs 64 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Curves 49 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Typical Systems 67 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Tuning 49 kB PDF file donated by Eric Lemmon WB6FLY
"C" Series Parts 71 kB PDF file donated by Eric Lemmon WB6FLY

Telewave
TPRD-series Duplexer Tuning Instructions   46 kB PDF file
Generic tuning instructions for their pass/reject duplexers.
TPRD-1554 and 1556 Duplexers   91 kB PDF file
These are VHF pass-reject duplexers good for 350 watts. The TPRD-1554 is VHF 4 cavity and the 1556 is 6 cavity.
TPRD-4544 and 4744 Duplexers   107 kB PDF file
UHF 4 cavity pass-reject, 250watts. The 4544 model is for 400-470 MHz, the 4744 is for 470-512 MHz.
TPRD-9044 Duplexer   88 kB PDF file
890-960 MHz 4 cavity pass-reject, 250 watts
If 4 cavities are enough in your RF environment then this is an ideal unit for 900 MHz amateur repeaters.

TX-RX
Overview of TX-RX Low Band Duplexers 2 MB PDF   Also has some Tech Aid documents
Overview of TX-RX High Band and 220 MHz Duplexers 2 MB PDF   Includes a chart explaining their model numbering system
Hint: The center digit pair are the magic numbers:
13=30-40 MHz,   14=38-50 MHz,   29=88-108 MHz,   36=132-150 MHz,   37=144-174 MHz,   38=132-174 MHz,   41=148-174 MHz,   52=215-250 MHz,   65=406-430 MHz,   66=442-450 MHz, and 97=1215-1300 MHz.
Data Sheet on the TX-RX model 28-37-02A 144-175 MHz duplexer 2.7 MB PDF
If a 4-cavity model is enough for your situation, this is the ideal model for a 2m repeater - it will handle 400 watts at 500 KHz spacing with 85 dB of isolation. Otherwise look at the 28-37-11, it's the 6-cavity version with 100 dB. Personally, I'd rather have the extra headroom of the 6-cavity version. And TX-RX will sell you an upgrade kit of the extra cavities and cables.
Instruction Manual on the Vari-Notch Duplexers (4" Cavities)   673 kB PDF
This is a generic manual for TX-RX duplexers using four inch cavities.
Instruction Manual on the Vari-Notch Duplexers (6" Cavities)   189 kB PDF
This is a generic manual for TX-RX duplexers using six inch cavities.

WACOM and Remec
WACOM started out as Waco Communications in Waco, Texas. At some point WACOM was bought by Remec, and in November of 2001 was sold to TX-RX.
Notes on the Wacom WP-641 BpBr Cavity   by Kevin Custer W3KKC
Field Tuning Instructions for Remec WP-604, WP-609, WP-612, WP-621, WP-629, WP-639 and WP-641 VHF Duplexers   283 kB PDF donated by Eric Lemmon WB6FLY
There's one repeated error in this writeup... In Figure 1 and Figure 2 you need to terminate the unused port with a good dummy load.
Field Tuning Instructions for Wacom WP-604, WP-609, WP-612, WP-621, WP-629, WP-639, WP-641 and WP-652 units   973 kB PDF donated by Ivan OZ1HYG
This is an earlier version of the above file (it's from Wacom), and the instructions are a little different.
Field Tuning Instructions for Wacom WP-678-R2 and WP-665-R2 UHF Duplexers   746 kB PDF donated by Eric Lemmon WB6FLY
Spec Sheet for WP-604 (low band, 4-cavity)   371 kB PDF
Spec Sheet for WP-621 and WP-641 (high band, 4-cavity)   218 kB PDF
Spec Sheet for WP-623 and WP-643 (high band, 6-cavity)   178 kB PDF
Spec Sheet for WP-629 and WP-639 (high band, 4-cavity)   188 kB PDF
Spec Sheet for WP-652 and WP-653 (220mc, 4-cavity)   248 KB PDF   This is the March 1997 version of the sheet.
The September 1985 version (no image yet) has a few differences: the older sheet says 220-300 MHz, 1.0 MHz min. spacing, 350 watts max, gray enamel finish.
The newer sheet says 210-260 MHz, 1.0 MHz min. spacing, 200 watts max, black enamel finish.
The frequency response charts look identical, as do the loss and isolation specs.
Spec Sheet for WP-665 and WP-678 (UHF, 4-cavity)   215 kB PDF
WP-687-3943 Catalog Sheet (900 MHz, 4-cavity)   145 kB GIF
WP-687-3943 Spec Sheet (900 MHz, 4-cavity)   1.65 MB PDF
WP-687-3943 Test Sheet (900 MHz, 4-cavity)   1.35 MB PDF
WP-687-3943 Field Tuning Instructions (900 MHz, 4-cavity)   409 kB PDF
WP-4941-7941 Spec Sheet (900 MHz, 2-cavity)   2 MB PDF


Antennas

Introductory Information on Antennas   READ THIS FIRST   There is a section on mobile antennas and projects towards the bottom of this web page.
Radio Antenna Engineering   By Edmund A. Laport   This is a 1952 textbook and the original copyright has expired. The PDF file is 24.5 MB. At the time, Mr. Laport was the Chief Engineer of RCA International Division. While the book is oriented towards antennas up to 30 MHz, the Preface is worth reading (4 pages) as theory doesn't depend that much on wavelength. The Introduction (11 pages) has some math, but it's also very interesting.
The W1GHZ Online Microwave Antenna Book   By Paul Wade W1GHZ (ex N1BWT)   An excellent text, and worth reading. (offsite link)
Antenna Design for Omnidirectional Repeater Coverage   1 MB PDF By James Ruxlow N9SN
What do you do when you need omni coverage, and you have to side mount the antenna to a triangular tower that is over fifteen feet on each face? The Western Illinois ARC figured it out. And their solution works well.
Precipitation Static and Duplex Radio... The Phenomena and the Cure!   Rain and snow clouds contain more than rain and snow   By Kevin Custer W3KKC.
Help!! I have a crackling noise in my repeater   Why it's there and how to cure it... By Kevin Custer W3KKC.
Vertical and Horizontal antenna separation charts   Provided by Kevin Custer W3KKC.
Information on a Cycloid Dipole (also known as circular polarization) antennas   By the WA7X crew   (offsite link)
Calculating Downtilt   39 kB PDF By Scala Division of Kathrein Corp (Technical Bulletin #112)
Calculating Downtilt and Distance By Bryan K. Dorbert N3ST
Side Mounted Radiation Patterns   123 kB PDF By Scala Division of Kathrein Corp
Appears to be a scan of a page from from a catalog.
Side mount antenna patterns   279 kB PDF file
A scan of a page from the "Engineering Notes" section in an old DB Products catalog
Omni-Directional Gain Vertical Collinear Construction Project   By Mike Collis WA6SVT
Yes, you too can build a Stationmaster - for any frequency from 2 meters to 1.3 GHz
This writeup originally appeared in the May 1982 issue of 73 magazine, later revised in the August 1990 issue of 73 magazine.
Some variations and constructions ideas on the WA6SVT UHF collinear   by Kevin Custer W3KKC
One ham's experiences with the WA6SVT antenna   by Paul Kelly N1BUG
Here's the construction article promised in the above article   by Paul Kelly N1BUG
Build A 9 dB, 70cm, Collinear Antenna From Coax   By Michael Martell N1HFX   (offsite link)
Yes, you can build a decent home base station antenna from RG-58 coax.
Fiberglass Antenna Painting Procedure   318 kB PDF By Celwave Corp. provided by Mike Dees N3EZD. See the next article as well.
Some Notes on Fiberglass Antenna Painting   Comments from several folks that accompany the above article.
Retuning a Stationmaster type antenna   By Jim Barbour WD8CHL
Some Notes On Stationmaster-Type Antennas   by Karl Shoemaker, AK2O of the Spokane Repeater Group   (offsite link)

  Advanced Electronic Applications / AEA
For information on AEA antennas including the Isopole please see the AEA page.

  Andrew
2008 Andrew Corp. Base Station Antenna Systems Product Selection Guide   3 MB PDF

  Antenna Specialist
Antenna Specialist 3 and 5 element yagi antenna instructions   408 kB PDF

 Celwave
A detailed drawing by Skipp of the Celwave-built Motorola TDE6090A welded yagi beam antenna   70 kB PDF   This is a two page PDF, the first page is Skipp's measurements, the second is the Celwave drawing. There is enough information here that anyone with a welder could make their own very strong winter-ice-proof welded 10 dB gain yagi antenna. Note that the element length measurements shown in the diagram are for 420 MHz frequencies.
If you need a physically strong very good UHF point-to-point link antenna then use this design as your model.
A PDF of a fax describing the Celwave low band dipoles   170 kB PDF
The products include the PD320 (one element, 2.5db, 10 feet of tower space), PD322 (two elements, 5.0db, 24 feet) and PD324 (four elements, 7.5db, 55 feet) side-mount antennas.
Celwave 220 brochure   579 kB PDF
Back when 220-222 was stolen from the hams to be a new land mobile radio band Celwave put together a brochure with the tech specs on all of their 220 products plus three sample system diagrams.
The products include the PD220-8, PD220DT, 92.0101, and 93.0024 antennas, the TJD220-5T transmitter combiner, PD1604B cavity, PD5042-2 duplexer, PD5279 cavity, PD5280-1, PD5280-2 and PD5280-3 duplexers, PD1602 low-pass filter, PD506-2A duplexer, PD5091-2A dual notch cavity, PD5090-2B/3 bandpass filter and the PD5090-2A bandpass cavity.

  Cushcraft
Cushcraft 410B and 424B Instruction Manual   2 MB PDF
Cushcraft AFM-4DA, AFM-24DA, AFM-44DA Instruction Manual   410 kB PDF

  Decibel Products / RFS
IMPORTANT !! A letter suffix indicates the range that an antenna is built for: 138-150 MHz, 150-160 MHz, 155-165 MHz, or 164-174 MHz but that the actual end frequencies and the assigned letter is NOT consistent across the product line. For example, on one product (i.e. one model number) an "A" model might be 150-159 MHz, while on another product an "A" model might be 150-155 MHz (4 MHz narrower). While in many cases an "A" range is the one that starts at 150 MHz, it can vary with EACH antenna model number: one antenna might have "A" be the 138-150 MHz range, and another might have "E" be the 138-150 MHz range. Be very careful that you check your range letter definition before you spend your money (on new or used antennas) !
A list of DB Products antenna models and data   68 kB PDF file   compiled by Robert Meister WA1MIK in August 2012.
Data sheet on the DB-201 ground plane omni antenna:
This is the so-called "bent-over" ground plane that is rated at unit gain and 500 watts.
This is a one-page version from the Allen Telecom vintage   733 kB PDF file
It was available for any frequency from 30 MHz to 512 MHz. The ranges are: A=30-33 MHz, B=33-37 MHz, C=37-42 MHz, D=42-50 MHz, E=66-88 MHz, F=100-144 MHz, G=144-150 MHz, H=150-174 MHz, J=225-406 MHz, JJ=220-222 MHz, K=406-512 MHz, L=Uncut 30-50 MHz, M=Uncut 144-174 MHz, N=Uncut 406-512 MHz.
This is a two-page version from DB Products   166 kB PDF file dated 1995.
Cutting chart for the DB-201   Page 1 159 kB   Page 2 111 kB   Allen Telecom version courtesy of Russ Stafford W3CH
The same info in a 4 page PDF, better presented, from DB Products   855 kB PDF file
The complete cutting chart for the DB-205 coaxial antenna   185 kB PDF file donated by Jim K1VTY, cleaned up and reduced in size by Bob WA1MIK. The charts cover 33-174 MHz.
A poor scan of the data sheet on the DB-212 side mount omni antenna (33-88 MHz)
Page 1 260 kB   Page 2 203 kB   Drawing of the diagram on Page 2 34kb
Here's the Andrew version of the same catalog sheet   108 kB PDF file (a much better scan) courtesy of Allen Wilde N1IOE
and here's the DB-212 tower mounting instructions   141 kB PDF also courtesy of Allen Wilde N1IOE
  You can move a low band DB-212 to 6m by basically freeing up the trombone section of the antenna, adjusting the postion, then locking it down again. Just measure the current length of the dipole and then multiply this length by (current-freq divided by the new-freq). So if the current length is 184 inches and the current freq is 46 MHz and your destination frequency is 52.5 MHz the new length (in inches) is therefore 184*(46/52.5).... To change the length you will need to remove the pop-rivet and a little dimple that the production line uses to hold the trombone in place until the rivet is installed. Sometimes the VSWR depends on the tower face. If you want to super tune the antenna set the antenna up on a tower leg several feet off the ground, preferrably a little over a 1/2 wave if you can do it. Then adjust the trombone to the length you calculated and apply a little RF power and check the reflected power. Then get a long stick and start moving the trombone slowly while watching the reflected power. When you get the best possible VSWR, stop and redo the rivets. Personally I'd add a bead of non-acidic silicone bathub sealer to water-seal the joint.
Detailed measured diagram of the low-band four-element DB-212 wiring harness   Courtesy Bill Cotter N4LG.
WA1ZYX's web page about modifying the DB-212 elements for 6 meters   Offsite Link.
Detailed harness lengths for various DB-222 multi-bay antennas   Courtesy of Paul Dumdie W9DWP.
DB-224 catalog data (PDF files): Decibel DB-224 Data Sheet  154 kB PDF file   Andrew DB-224 Data Sheet  140 kB PDF file   DB-224 Instruction Sheet  158 kB PDF file
Here's the instruction sheet that comes in the box with the DB-224   Page 1 964 kB   Page 2 1,032 kB   Page 3 819 kB   Courtesy John Lock KFØM.
The DB-224 is the standard antenna that all other 2m/ high band repeater antennas are measured against. The nearest substitute for the DB-224 is the RFS Celewave 340. Both cost a little more than a fiberglass antenna but will easily last 20-30 years, and don't have the cracked joint duplex noise problem, nor will you have a pile of fiberglass toothpicks on the ground after a nearby lightning strike. How many Hustler, Comet or Diamond antennas will you go through in 20-30 years?
The DB-224 is rated at 80 MPH winds, but that's wishful thinking unless you side mount it with clamps on BOTH the top AND the bottom. Frankly, chosing to mount your antenna on the tower top only to get a few extra feet isn't worth a bent or broken metal support tube, and if your antenna is side mounted (even if the tip is only 6 feet down from the tower top) the tower itself (or someone else's antenna) can be the lightning rod and take the hit.

Note that all "DB-224"s are not the same... they may all be tower-mounted exposed dipole arrays with 6 to 8 dB of gain (depending on the pattern), it's the suffix letter that is of utmost importance:
  • the DB-224-A model is 150-160 MHz circular pattern,
  • the DB-224-B model is 155-165 MHz circular pattern,
  • the DB-224-C model is 164-174 MHz circular pattern,
  • the DB-224-E model is 138-150 MHz circular pattern (but try and find one second hand...),
  • the DB-224-FAA model is 127-141 MHz circular pattern (it can be shortened to 2m),
  • the DB-224-F model is 160-170 MHz circular pattern,
  • the DB-224-J model is 276-285 MHz circular pattern,
  • and the DB-224-JJ model is 220-225 MHz circular pattern,

  • the DB-224E-A model is 150-160 MHz offset pattern,
  • the DB-224E-B model is 155-165 MHz offset pattern,
  • the DB-224E-C model is 164-174 MHz offset pattern,
  • the DB-224E-E model is 138-150 MHz offset pattern (again, try and find one second hand...),
  • and the DB-224E-JJ model is 220-225 MHz offset pattern,

  • The DB-224 series can be ordered as a single or dual antenna. Just modify the model number by adding an "S" in the right spot - a DB-224-JJ single antenna becomes a DB-224S-JJ as a dual antenna. It amounts to separating the elements into two independent antennas on the same mast. Each antenna has a separate feedline terminated at the bottom of the mast. A DB-224ES-A or DB-224ES-JJ is a dual feedline antenna with the offset pattern.

  • And I've been told that at one point (maybe still can) you could order a new DB-224 less the tubular mast, and supply your own. Supposedly one group built up a "single antenna" as defined by their tower agreement that was made up of a UHF stationmaster-type fiberglass stick on the top of an extended length tube, a VHF DB-224 in the middle, and a end-mount UHF beam clamped a couple of feet below the bottom element and a few inches above the lower end of the tube.
A detailed drawing of the DB-224-A and DB-224-E   106 kB PDF file donated by Skipp. Note that the element length measurements are shown for both the "A" (150-160 MHz) range and the "E" (138-150 MHz) range. There is enough information here that anyone with some experience bending aluminum tubing can build one for themselves. Or if you are going to build your own and want extra strength you could use aluminum rod.
A detailed drawing of the DB-224-JJ   14 kB PDF file   Roger White W5RDW measured a DB-224-JJ, the drawing is by Skipp.
Another detailed drawing of the DB-224-E   61 kB PDF file Donated by Doug Zastrow WBØUPJ. Note that the element length measurements shown in the diagram are for 136-150 MHz frequencies.
More DB-224 wiring harness drawings   56 kB PDF file. Complete with calculations.
Details of the DB-224-E wiring harness   1.7 MB PDF file. Additional detailed drawings of various parts of the wiring harness can be found below (all are PDF files):
Conversion calculations for moving your DB-224 to a different band split.   90 kB PDF file   All of the magic calculations plus coax types necessary to redo your DB-224's wiring harness and set the element length and spacing.
Converting a DB-224 or DB-222 to the 2M ham band   Original author KC4WC
The DB-225 is a single element, 5 dB gain dipole station antenna that provides a "semi-circular radiation pattern" (their term, not mine). It uses a director element that is built into the dipole assembly to shape the pattern - if you end up with a used one and it is missing the director there's no telling what the final pattern will look like... The antenna can be ordered for any frequency from 30 MHz to 174 MHz. The catalog claims that you can stack the antennas and get 8 dB gain with 2 antennas and 11 dB gain with 4 antennas. The data sheet is very specific that it must be mounted "2 to 3 feet below the top of the tower or pipe support. At the same time it must be clear of all guy wires or metal objects for 2 to 3 feet."
From an email from Ken Decker WA6OSB: Here's the paperwork that was shipped with a DB-225. I thought it might be useful in the R-B Antenna section.
DB-225 data   303 kB PDF file
The DB-228 is essentially two DB-224s on one 41-foot long mast, and can be ordered with a phasing harness that makes it one antenna - and that makes it the ultimate 2m repeater antenna (10 to 12 dB depending on the pattern). The catalog sheet shows the "normal" mounting has being a split mount: the top half is above and the bottom half is below the top of a tower (i.e. the bottom half is side mounted with two clamps at the middle and bottom); however, unless you want to be the lightning rod the DB-228 can be fully side mounted with the two brackets at top and bottom, or an optional third bracket can be added in the middle (I certainly would, especially in any area that has a problem with high winds, antenna icing, or both).
Or if you need extra RX-TX separation: order it with the -S (split kit) option and use it with two feedlines and a split duplexer as separate DB-224 receiving and transmitting antennas.
Note that on this antenna an A suffix indicates 150-160 MHz, B=155-165 MHz, C=164-174 MHz and E=138-150 MHz.
DB-228 Data Sheet  89 kB PDF file   DB-228 Instruction Sheet  62 kB PDF file
Here's the instruction sheet that comes in the box with the DB-228   772 kB PDF   Courtesy John Lock KFØM
DB-264 installation instruction sheet   159 kB PDF file Courtesy of Paul Kelly N1BUG
The DB-264 is a 4 element dipole array that is constructed for any 10 MHz segment of 150-285 MHz. This is the model that has the feed harness hidden inside the support pipe. I've seen one of these on 224 MHz, and it's rugged!
DB-304 4-bay VHF harness data sheets   450 kB PDF file Courtesy of Jim Dempsey, PDF'd by Bob WA1MIK
15 pages of detailed factory manufacturing and assembly information.
DB-314 instruction sheet   114 kB PDF file
The DB-314 is essentially a 8 UHF dipoles (a DB-408,6.6 dB gain) and 4 high band dipoles (half of a DB-304, 3.2 dB) on the samemast, with separate feedlines. If you need a commercial grade dual band antenna, this is it. Or if you are limited to one antenna, then order this guy and use it as separate 2m and 440 antennas with two feedlines, or with a pair of commercial-grade TX-RX Corp. (or similar)"diplexers" that put both antennas on one feedline. But don't try and use one on a 147.09 MHz; repeater paired with a second repeater whose input is 441.275 MHz, or 147.36 MHz; and paired with 442.075 MHz; (I shouldn't have to tell you to do the math... and it doesn't matter what antenna you have in that situation).
The DB-404 UHF dipole array is two pairs of UHF dipoles mounted to a mast.   Photo   Here is the factory data: DB 404 Data Sheet  95 kB PDF   DB 404 Instruction Sheet  134 kB PDF   Catalog sheet Page 1  879 kB   Catalog sheet Page 2  568 KB
The frequency range suffix: A = 406-420, B = 450-470, C = 470-488, D = 488-512, and the "E" range is either 482-494 or 440-450 depending on which catalog you read, be very, very careful when ordering one of these. Do it by frequency range, not suffix letter. The SWR is specified as under 1.5 (or less) across the entire range specified in the suffix letter. According to the spec sheet the standard connector is a male N, but I've seen installations with a PL-259 on the harness, and it looked like a factory harness.
A detailed drawing of the DB-404-B   30 kB PDF file Donated by Skipp. Note that the element length measurements shown in the diagram are for 450-470 MHz frequencies.
A detailed drawing of the DB-404-D   28 kB PDF file Donated by Skipp. Note that the element length measurements shown in the diagram are for 488-512 MHz frequencies.
The DB-408 is essentially two DB-404s stacked on one longer mast (almost 9.5 feet long) and can be ordered with one or with two feedlines (the "split kit"). Specify Omni or Offset pattern when ordering, and if top or side mounting when ordering. For side mounting order the DB-5012 mounting kit.
Here is the DB-408 UHF dipole array factory data: DB-408 Data Sheet  92 kB PDF file   DB-408 Instruction Sheet   81 kB PDF file
On this antenna the power limit is 250w, the frequency range A = 406-420, B = 450-470, C = 470-488, D = 488-512.
The "E" range is either 482-494 or 440-450 depending on which catalog you read, be very, very careful when ordering one of these. Do it by frequency range, not suffix letter.
A detailed drawing of the DB-408-B   29 kB PDF file Donated by Skipp. Note that the element length measurements shown in the diagram are for 450-470 MHz frequencies.
DB-411 UHF dipole array factory data: (PDF files) DB 411 Data Sheet  75 kB PDF file   DB 411 Instruction Sheet  223 kB PDF file
A detailed drawing of the DB-411-B   25 kB PDF file Donated by Skipp. Note that the element length measurements shown in the diagram are for 450-470 MHz frequencies.
The DB-420 is essentially two DB-408s stacked on one longer mast and can be ordered with one or with two feedlines (the "split kit"). Specify Omni or Offset pattern, and if top or side mounting when ordering.
A drawing of the DB-420-B phasing harness   143 kB PDF file
This is the 450-470 MHz version. Anybody have a drawing (or the measurements) for 440-450 MHz ?
The data sheet on the DB-420 UHF dipole array   117 kB PDF file   The DB-420 is an array of 8 dual dipoles that can be configured as a single 8-element antenna or as two 4-element antennas on the same mast (conversion requires a different harness).
The DB-420 UHF dipole array Assembly and Mounting Instructions   148 kB PDF file
Factory 1-page data sheet on the DB-492, DB-493 and DB-498 806-960 MHz Yagi beam antennas   133 kB PDF file
This is the data sheet on the welded beams that are 6, 8 or 9 dB. The 492 and 493 are light duty, the 498 is heavy duty. Phasing harnesses for 2 or 4 antennas are available for up to 15 dB of gain.
Factory 2-page data sheet on the DB-844H90E-XY directed dipole antenna   122 kB PDF file
806-896 MHz and 870-960 MHz antennas with 12-15 dB of gain.
Factory 4-page data sheet on the DB380 pipe mounts   237 kB PDF file
Also for DB5083 downtilt mounts for panel antennas.
Factory data sheet on the DB-5004 / DB-5030 Outrigger   387 kB PDF file
This is the data sheet on the fiberglass outrigger that supports the Stationmaster and SuperStationmaster style fiberglass monopoles. You want to use at least one, in really high wind/bad weather areas I've seen two on a 21 foot SuperStationmaster).

  Motorola
Over the years Motorola house-labeled many products actually made by Antenna Specialists, DB, PD, and others. If anyone has a translation list or chart (even just a few model numbers) we'd love to offer it here.
  The 1964 manual for the TAD1000-series coaxial VHF antennas   155 kB PDF Donated by Skipp   Description, Installation, Assembly, Parts.
Covers the models TAD1001x, TAD1002x, TAD1003x, TAD1004x, TAD6071x, TAD6072x, TAD6073x, TAD6074x (where "x" is an "A" or a "B").
  VHF unity-gain antenna model information and specifications for the TAD1010-series antennas   261 kB PDF Donated by Skipp
More info on the TAD1001, TAD1002, TAD1003 and TAD1004 models listed above, plus info on the TAD1012x, TAD1013x, TAD1014x, TAD1021x, TAD1022x, TAD1023x and TAD1024x series (where "x" is an "A" or a "B").
  VHF 3dB-gain antenna model information and specifications for the TDD602x-series antennas   244 kB PDF Donated by Skipp
Covers the models TAD6021A, TAD6022A, TAD6023A and TAD6024A units.
  VHF 5.5dB-gain antenna model information and specifications for the Motorola branded Stationmaster style antennas   274 kB PDF Donated by Skipp
This sheet covers the models TDD6071A, TDD6072A, TDD6073A, TDD6074A, TDD6075A, TDD6081A, TDD6082A, TDD6083A, TDD6084A, TDD6085A, TDD6090A, and TDD6100A.

 Phelps-Dodge
  Phelps-Dodge 4-bay VHF antenna assembly drawing   1 MB PDF file

 Telewave     Click here for the Telewave on-line catalog
  Does anyone have additional data sheets or scans of the box-stuffing literature that Telewave ships with their antennas?
  Telewave Antenna Connection weatherproofing   89 kB PDF
  Telewave 138-152-MHz-Yagi   189 kB PDF
3 elements, 5dB, 500w, 38 inches boom length, 42 inches longest element
  Telewave 415-450-MHz-Yagi   166 kB PDF
7 elements, 10 dB, 500w, 41 inches boom length, 13 inches longest element
  Telewave Discone Antenna 75 MHz to 3 GHz   75 kB PDF
(500w, SWR is between 3:1 and 1.5:1 below 95 MHz, 110 degree vertical beamwidth, 53 inches tall, 26 inches diameter, shipping weight is 102 pounds)
  Telewave Discone Antenna 118 MHz to 3 GHz   90 kB PDF
(500w, SWR is less than 1.5:1, 110 degree vertical beamwidth, 36 inches tall, 25.5 inches diameter, shipping weight is 10 pounds)
  Telewave Discone Antenna 400 MHz to 3 GHz   65 kB PDF
(500w, SWR is less than 1.7:1, 110 degree vertical beamwidth, 48 inches tall, 8 inches diameter, shipping weight is 41 pounds)
  Telewave Dipole Mounting   32 kB PDF
  Telewave Dipole Pattern Configuration 30-300-MHz   171 kB PDF
  Telewave Dipole Pattern Configuration 300-1000 MHz   179 kB PDF
  Telewave 45-54 MHz dipole antenna   127 kB PDF
500 watts, 1 to 2.5 dB, occupies 9 feet of tower space
  Telewave 138-174 MHz dipole array   161 kB PDF
(single, dual and four elements, 500w, 1-9 dB depending on element count and pattern)
  Telewave 138-174 MHz dipole array   161 kB PDF
(8 elements, 500w, 7-12 dB depending on pattern - and it occupies 41 vertical feet of tower!)
  Telewave 216-252 MHz dipole array   161 kB PDF
(single, dual and four elements, 500w, 1-9 dB depending on element count and pattern)
  Telewave 216-252 MHz dipole array   161 kB PDF
(8 elements, 500w, 7-12 dB depending on pattern)
  Telewave 406-512 MHz dipole array   164 kB PDF
(single, dual and four elements, 500w, 1-9 dB depending on element count and pattern)
  Telewave 406-512 MHz dipole array   171 kB PDF
(8 elements, 500w, 7-12 dB depending on pattern)
  Telewave 800-1,000 MHz dipole array   162 kB PDF
(single, dual and four elements, 500w, 1-9 dB depending on element count and pattern)


Towers

How to look up towers   Search all of the FCC registered towers - broadcast, cellular, everything... (offsite link - to the FCC server)
Tower lookup page at the FCC web site   (offsite link - to the FCC server)
The Rohn Towers 2004 Catalog   31 MB PDF file
We'd like to get a scan of other tower catalogs as well.


Feedline, Coax, Connectors and more...

Introductory Information for Feedline, Connectors, and Coax   READ THIS FIRST
What Does "RG-6" Mean?   A nice explanation of where the "RG" in cable numbers came from.   (Offsite link)
Yes, it's TV and Video oriented, but it's still pertinent. And he explains why you want to specify Belden 1505A for any RG-59 sized video cable, and Belden 1694A for an RG-6 sized cable.
A document on the properties of different types of UHF (PL259) connectors.   2.6 MB PDF file by Allan B. Crites WA9ZZU
As a result of my extensive review of documents in my possession and in response to the document referenced above I am the author and others only extracted parts to be used in an Engineering Report which included my measurements and log book gathered data, and drawings, to which my engineering supervisor appointed by the company assembled the data and other pages, and added his name first above mine, even tho I had done the work.
You Kevin Custer, do hereby have my permission to publish this document in its entirety on your website Repeater Builder. Allan Crites WA9ZZU
WA2ISE's chart of the specs of common coax cables   By Robert Casey WA2ISE
More specifications (bend radius, velocity factor, loss) of common coaxial cable types
Yet another chart of cable specifications of common coaxial cable types   119 kB PDF by TX-RX Corporation
But it's only a couple of dB !    by Mike Morris WA6ILQ
Connector and feed line losses DO add up!
Amphenol Coax Cable Catalog version W1   16 MB PDF Courtesy of John Lovallo W9GC
I have no idea what year this was published, but it has to be pre-1963 as it's pre-ZIP codes.
Double Shielded Coax Cable   The differences between RG-142 and RG-400, and why sometimes you DON'T want to use RG-142... by Eric Lemmon WB6FLY
With a few additional notes on RG-214 and RG-223...
Shielding Effectiveness...   A 283 kB PDF Document by Andrew Corp. covering the types and parameters of shielded cables.
Installing PL-259 connectors on FSJ1-50A 1/4" Superflex Heliax   a photo article by Tony King W4ZT.
9913 data sheet   98 kB PDF from the Belden web site
Belden 9913 has an aluminum foil shield under a tinned copper braid. Like the LMR-nnn cable (where nnn is any 3 or 4 digit number) it is not appropriate for duplex service. The original Belden 9913 was an indoor-only low loss version of RG-8/U designed for the old thick Ethernet. Later versions have a tougher outer jacket, and at one point jumpers made from 9913 were shipped with commercial LMR antennas.
MIL-SPEC-C17 for RG-9/U dated 25-July-1946   40 kB PDF courtesy of Eric Lemmon WB6FLY
RG-9 is an older double shielded cable that had a center conductor of 7 strands of 21 ga silver plated wire, an inner braid of 34 ga silver plated braid and an outer shield of 34 ga unplated copper braid.
MIL-SPEC-C17 for RG-9A/U dated 25-July-1946   40 kB PDF courtesy of Eric Lemmon WB6FLY
RG-9A/U was the same as RG-9/U except that on the A series cable both braids were silver plated.
MIL-SPEC-C17 for RG-9B/U dated 07-September-1955   32 kB PDF courtesy of Eric Lemmon WB6FLY
This cable has a loss of 5.5 dB per 100 feet at 400 MHz.
Genuine RG-9B/U cable has two silver-plated copper shields and a silver-plated stranded copper center conductor- just like RG-214/U. In fact, the Cancellation Notice for RG-9 dated 12 November 1969 states, "Forfuture procurement, use the latest issue of Military Specification Sheet MIL-C-17/75, which covers Cable, Radio Frequency, Coaxial, RG-214/U."
MIL-SPEC-C17 for RG-21A/U and RG-222/U dated 7-sep-1955   82 kB PDF courtesy of Eric Lemmon WB6FLY
RG-21 is considered obsolete and has been replaced by RG-222 in all new designs. This is a high loss cable, over 30 dB per 100 feet at 400 MHz.
MIL-SPEC-C17 for RG-58A/U dated 18-July-1985   268 kB PDF courtesy of Eric Lemmon WB6FLY
This is the mil-spec for real RG-58.   Most of what is sold as RG-58 these days isn't anywhere close to mil-spec stuff - all you have to do is check the density or tightness of the braid, then count the strands on the inner conductor (and make sure it's tinned).
The mil-spec calls for a tinned copper braid and a center conductor of 19 tinned strands - and I've found "mil spec" RG-58A/U with a solid center conductor at one HRO store, and I've found "mil spec" RG-58A/U without the tinned braid or tinned center conductor at both HRO and AES retail stores. The data sheet says that the good mil-spec stuff has a loss of 4 dB per 100 feet at 50 MHz, 9 dB per 100 feet at 150 MHz, and 17 dB per 100 feet at 400 MHz!   If the good stuff loses 1/4 of your power at 2m or half your power at 440 MHz in just 20 feet of cable, what's the loss on the cheap stuff going to be?
Note that this is a PVC based cable that can no longer be used in aerospace applications due to the fact that when PVC is burnt (i.e. with flames) it gives off toxic gas.
JAN-C17 for RG-83/U dated 25-JUL-1946   68 kB PDF courtesy of Eric Lemmon WB6FLY
This is the Joint-Army-Navy spec for the 35 ohm coaxial cable whose major use today is in the phasing harnesses for multi-antenna (or multi-element in a single antenna) arrays.
MIL-C-17_92D for RG-115 Note 2 dated 23-Oct-2000   136 kB PDF courtesy of Eric Lemmon WB6FLY
This cable has a silver plated center conductor, double silver plated shields, is appropriate for temperatures from -55 degrees C / -67 degrees F to +230 degrees C / 446 degrees F and due to the fiberglass outer jacket is suitable for direct burial applications. It has a loss (per 100 feet) of 1.6 dB at 50MHz, 2.5 dB at 100 MHz and 9.8 dB at 1,000 MHz (about 6 dB at 450 MHz from my reading of the graph on page 6 of the PDF file). The PDF file also has return loss specifications.
MIL-DTL-17/60D (with Ammendment 1) for cable type RG-142 dated 12-Oct-2006   135 kB PDF courtesy of Eric Lemmon WB6FLY
This is the mil-spec for real M17/60-RG142 - the stiff stuff with a solid inner conductor of silver plated copper covered steel wire, a solid, extruded PTFE dielectric core, dual 36 ga silver-coated copper braids, and less than 30pf of capacitance per foot. Note that this coax is intended for use as RF jumpers in general purpose, high temperature, vibration and movement-free applications, NOT as feedline. The loss per 100 feet is 3 dB at 50 MHz, and 9.3 dB at 400 MHz.
MIL-C-17_119G for RG-174: both courtesy of Eric Lemmon WB6FLY
JAN-C17-119G for RG-174 dated 20-FEB-1991   191 kB PDF
JAN-C17-196B for RG-174 dated 13-AUG-1993   27 kB PDF
This is small (less than .15 inch) diameter coax that is the proper size for SMA and SMB connectors. It works OK up to 1 GHz, but has a 85% braid coverage. The braid coverage is important, but the major drawback is the very high loss - per 100 feet is 10 dB at 100 MHz, and about 25 dB loss at 450 MHz. The small size contributes to the low power handling capability - don't run more than 25 to 30 watts through it at 150 MHz or 20 to 25 watts through it at 450 MHz. I've seen a melted piece of RG-174... not pretty. And when it shorted it killed the PA deck.
Personally, I won't use it at RF unless I have to, and despite the negatives listed above I do have a roll of it in my shop: I use it for audio coax in everything I build. My dad (WB6SOX) taught me a trick that you can use on both RG-58 and RG-174... you can peel back the outer jacket an inch or more, spread the braid a little just above the end of the jacket and use a spring hook to pull the center conductor through the hole in the braid. You can then put some tubing (heat shrink or normal) over the braid pigtail. This trick gives you two conductors that you can solder to dual pin termination, be they solder lugs, pins on a connector, etc.
MIL-SPEC-C17/74C for "Cables, Radio Frequency, Flexible, Coaxial, 50 Ohms, Unarmored M17/74-RG-213 and Armored M17/74-RG-215 dated 18-July-1985   311 kB PDF courtesy of Eric Lemmon WB6FLY
This is the mil-spec for real RG-213 - the stuff with 17 strands of copper wire, a solid, polyethelene dielectric core, a copper braided shield with better than 95% coverage. Note that this cable is intended for use as feedline in general purpose low temperature applications. It has a loss of 1.2 dB per 100 feet at 50 MHz, and 4.8 dB per 100 feet at 400 MHz (over 50% of your power!).
Note that this is a PVC based cable that can no longer be used in aerospace applications due to the fact that when PVC is burnt (i.e. with flames) it gives off toxic gas.
MIL-SPEC for RG-214 dated 24-Sep-1986   335 kB PDF courtesy of Eric Lemmon WB6FLY
RG-214 is the good double-shielded coax that has the stranded silver plated center conductor (each strand is individually silver plated). Both shields are made from 34ga silver plated copper wire. The inner shield exceeds 95% coverage and the outer shield equals or exceeds 98% coverage. It has a loss of 1.7 dB per 100 feet at 50 MHz, and 6.8 dB per 100 feet at 400 MHz (over 3/4 of your power!).
Note that this is a PVC based cable that can no longer be used in aerospace applications due to the fact that when PVC is burnt (i.e. with flames) it gives off toxic gas.
MIL-SPEC for RG-214 dated 1991   215 kB PDF courtesy of Eric Lemmon WB6FLY
This is the new RG-214 that meets the requirement of the vertical flame test. It has the aluminum coated polyester tape layer between the outer braid and the outer jacket.
This is Amendment 1 to MIL-SPEC C-17/75F for RG-214 and RG-365 dated 1998   4 kB PDF courtesy of Eric Lemmon WB6FLY
This is simply an administrative update.
RG-222/U - see RG-21 above
MIL-SPEC C-17/84B for RG-223 dated 1977   388 kB PDF courtesy of Eric Lemmon WB6FLY
RG-223 has been pretty much replaced in all amateur and LMR applications by RG-400. RG-223 is an RG58-sized coaxial cable that has a silver plated solid center conductor and double shielded silver plated braid. It has a loss of 4.8 dB per 100 feet at 50 MHz, and 12 dB per 100 feet at 400 MHz (in other words, less than 10% of your power makes it to the other end...)
If you read the spec sheet carefully you will see that RG-223 is rated for just 86 watts at 400 MHz. For higher power in this size cable you will want to use RG-400. RG-223 also has 50% greater attenuation at 50 MHz and 15% greater attenuation at 400 MHz than RG-400.
Note that this is a PVC based cable that can no longer be used in aerospace applications due to the fact that when PVC is burnt (i.e. with flames) it gives off toxic gas.
MIL-SPEC C17/127C-RG-393 for cable type RG-393 dated 11-May-1981   293 kB PDF courtesy of Eric Lemmon WB6FLY
RG-393 is the modern replacement for RG-214. It has similar construction with the stranded silver plated center conductor (each strand is individually silver plated). It has a solid extruded PFTE dielectric core. Both shields are made from 34ga silver plated copper wire. The inner shield exceeds 95% coverage and the outer shield equals or exceeds 98% coverage. It has a loss of 1.7 dB per 100 feet at 50 MHz, and 5 dB per 100 feet at 400 MHz. Page 4 of this PDF has a return loss spec and graph.
MIL-DTL-17/128B (with amendment 2) for cable type RG-400 dated 25-Feb-2005   94 kB PDF courtesy of Eric Lemmon WB6FLY
RG-400 is the RG58 size coax that has construction similar to RG-214. It has the stranded silver plated center conductor (each strand is individually silver plated). It has a solid extruded PFTE dielectric core. Both shields are made from 34ga silver plated copper wire. Both the inner and outer shields exceed 93% coverage. It has a loss of 3.2 dB per 100 feet at 50 MHz, 6 dB per 100 feet at 150 MHz and 10.55 dB per 100 feet at 400 MHz. Page 4 of this PDF has a return loss spec and graph.
Note that if you put 100 watts at UHF into a three-foot long jumper you will get about 93-94 watts out the other end, with a 6 to 7 watt loss in just THREE feet. It is high grade jumper material, not feedline!
Andrew FSJ1-50A spec sheet   124 kB PDF
This is the 1/4" superflex product with the copper plated aluminum center conductor... It has 2.2 dB loss per 100 feet at 150 MHz and 4 dB loss per 100 feet at 450 MHz.
Andrew LDF1-50 spec sheet   126 kB PDF
This is the 1/4" regular product with the corrugated copper jacket and the copper plated aluminum center conductor... It has 1.52 dB loss per 100 feet at 150 MHz and 2.71 dB loss per 100 feet at 450 MHz.
Andrew LDF2-50 spec sheet   121 kB PDF
This is the 3/8" regular product with the corrugated copper jacket and the copper plated aluminum center conductor... It has 1.28 dB loss per 100 feet at 150 MHz and 2.29 dB loss per 100 feet at 450 MHz.
Andrew LDF4-50A spec sheet   199 kB PDF
This is the 1/2" regular product with the corrugated copper jacket and the copper plated aluminum center conductor... It has 0.815 dB loss per 100 feet at 150 MHz and 1.447 dB loss per 100 feet at 450 MHz.
Andrew LDF5-50A spec sheet   167 kB PDF
This is the 7/8" regular product with the corrugated copper jacket and the copper plated aluminum center conductor... It has 0.45 dB loss per 100 feet at 150 MHz and 0.81 dB loss per 100 feet at 450 MHz.
Andrew LDF6-50 spec sheet   118 kB PDF
This is the 1 and 1/4" regular product with the corrugated copper jacket and the copper plated aluminum center conductor... It has 0.3 dB loss per 100 feet at 150 MHz and 0.544 dB loss per 100 feet at 450 MHz.
Andrew LDF7-50A spec sheet   128 kB PDF
This is the 1 and 5/8" regular product with the corrugated copper jacket and the copper plated aluminum center conductor... It has 0.25 dB loss per 100 feet at 150 MHz and 0.467 dB loss per 100 feet at 450 MHz.
We'd like to have similar info on the Heliax connectors.


Calculators (dBm / voltage, intermod, fade margin, etc.)

Converting between dbm and millivolts or microvolts   A no-math graphical calculator. It's only a xerox copy of the metal rim of a attenuator wheel from a Measurements Corp. Model 80 RF Signal Generator... but it's very handy. Courtesy of Ray Von Neumann K6PUW
I suggest that you print this out and tape it to the front panel of your signal generator that is calibrated in µV and mV only. Once you realize how dbM numbers work you will find yourself referring to it on a regular basis.
Converting between dbm and millivolts or microvolts   A no-math tabular calculator (a lookup table). The above xerox of the attenuator scale is easier to use.
dBm to Microvolts Conversion Chart   8 kB PDF By IFR Corp.   The above xerox of the attenuator scale is easier to use.
An online intermod calculator from Audio Technica   Note that this is oriented to wireless microphones, but since it handles up to 30 frequencies it is very handy. (offsite link).
Another downloadable intermod calculator   This one is shareware written by KE6QH.
FCC HAAT (Height Above Average Terrain) Calculator   (offsite link to the FCC web site)
FCC Coordinate Calculation Program   (offsite link to the FCC web site)
This is a useful calcualtor for point-to-point links... "This program will calculate the end coordinates, in degrees, minutes and seconds, given an initial set of coordinates, a bearing or azimuth (referenced to True North or 0 degrees), and a distance..."
FCC Coordinate Conversion Program   (offsite link to the FCC web site)
This utility permits the user to convert latitude and longitude between decimal degrees and degrees, minutes, and seconds. For convenience, a link is included to the National Geodetic Survey's NADCON program, which allows conversions between the NAD83 / WGS84 coordinate system and the older NAD27 coordinate system. NAD27 coordinates are presently used for broadcast authorizations and applications."
FCC Distance Calculation Program   (offsite link to the FCC web site)
This program will calculate the distance and azimuth (referenced to True North) between two sets of coordinates on the earth."

The last four calculators above are courtesy of Dale Bickel of the USA Federal Communications Commission. The FCC also has a number of "Conversions" calculators including FM Channel to Frequency, FM Frequency to Channel, TV Channel to Frequency Band, Feet to/from Meters, Miles to/from Kilometers, dBu to/from mV/m, kW to/from dBk, Relative Field, Transmission Line Efficiency, and more.
An old DB Products DOS program that calculates down-tilt for antennas   128 kB ZIP file
An old DB Products DOS program that plots some antenna patterns   383 kB ZIP file
An old DB Products DOS program that gives you some insight into the effects of side-mounting vertical antennas   134 kB ZIP file

The above three programs were supplied by Dave Gartner WD6AXM.

Mobile Antennas and Projects

Introductory Information on mobile antennas   READ THIS FIRST
A Motorized Mag Mount for Mobile Antennas   1.53 MB PDF from the May 2005 issue of QST
An interesting modification to an off-the-shelf Diamond mount.
Base and mobile antenna cutting chart from Larsen Antennas   684 kB PDF from the Larsen web site.
Mobile antenna patterns and designations   1.6 MB PDF from the Larsen web site.
Low band radios that cover a wide frequency range (like the GE Delta, GE Rangr, Motorola Syntor X or Syntor X-9000 which covers 28-54 MHz in one range) have a big problem: the antenna bandwidth is much narrower than the radio is - most low band antennas are limited to roughly 750 KHz to 1 MHz in bandwidth. The mobile HF antenna tuners made by YaeComWood (Yaesu, Icom and Kenwood) all require serial data from the HF mobile for the frequency information. In addition, very few of them will work on 6 meter frequencies. Motorized autotuning antennas have been around since before World War II, but a really good design is fairly recent (the so-called "screwdriver" design, invented and patented by Don Johnson W6AAQ in 1991 - almost all other units on the market are a direct pirated copy or a enhanced redesign of the original). Back in mid-1985 Motorola came up with a no-moving-parts solution: a "Diplex Antenna Matching" kit that allowed two differently cut low band whip antennas on one radio (i.e. one antenna could be on 36 MHz and the other on 43 MHz), and set up in a way that prevented them from interfering with each other. The two antennas can be cut to any two low band frequencies. Here is the complete documentation on the kit (Motorola manual part number 6880100W86, a 1.9 MB PDF), which contains three pages of info - enough to duplicate it yourself.
There is a local rumor that someone has extended the Motorola writeup and come up with a way to use three different whip antennas to allow three 1-mhz-wide "windows" but I've not seen it. At the moment if you need more than two fixed 1-mhz-wide "windows" then you need a good screwdriver antenna and a self-contained autotuner like one made by SGC. The phrase "self-contained" is important here, as the autotuners from YaeComWood are dependent on the radio they are connected to for serial frequency data and cannot be made to work with common low band Motorola or GE land mobile radios.
I have heard that there is an antenna tuner made for the "screwdriver" antennas that will work in this situation (from 28-54 MHz) but do not know who the manufacturer is. Let me now who it is and I'll put a link here.
Yes, there is a need. Picture a mobile EOC comm van that has a wideband Syntor X9000. Air Force SAR uses 33 Mhz frequencies. The California Highway Patrol uses 39-43 MHz. Red Cross has several channels around 47.3 to 47.6 MHz. The National Guard has channels in the 49 MHz range. Plus any 10m or 6m channels.
PS - if anyone wants to complete the Motorola writeup with the the coax measurents for 10m and 6m, or supply a replacement cutting chart that goes down to 28 MHz (or even 27 MHz) and up to 54 MHz we will publish it.
The KØBG web site   (link to another web site)
Alan Applegate KØBG lives in Roswell, New Mexico and has created a very good reference web site for mobile amateur radio operators. I was pointed to it by a police department radio tech. While the site has a lot of material oriented to HF mobile, there is a lot of information that is relevant to VHF operation as well. Just look at the index along the left edge. If you look at nothing else, the Alternators and Batteries page and the Antenna Mounts page is worth your time. And if you have (or are going to buy) a screwdriver antenna then his comments are REALLY worth your time.
W8JI's page on Inductors and Loading Coil Current (Mobile and Loaded Antennas)   (link to another web site)
Charles Rouch has a good web page on loading coils and how they work. It's HF oriented but the math is the same.
Urgent Communications Mobile Radio Installation Notes   (link to another web site)
Urgent Communications is a two-way radio industry publication, and their web site has some notes on mobile radio installations.
You've heard of co-phased antennas? Well, here's the co-tanger antenna.


Home Brew Antennas, Projects, Etc.

A mobile coaxial sleeve dipole antenna for 2m   450 kB PDF from the Aug 2001 issue of QST
The sleeve vertial (actually a coaxial dipole) is handy when you have no ground plane to work with, like on a bicycle, a motorcycle saddle bag or a Corvette rear deck. Back in the 1970s Art Gentry K6MYK used to have both VHF and UHF homebrew ones on his car, and said that they outperformed any 1/4 or 5/8 wave antenna.
440 MHz Folded Dipole Repeater Antenna   222 kB PDF file   This is a two page PDF file of the classic 73 Magazine construction article by Chuck Kelsey WB2EDV - yes, you can build yourself a DB-224 folded dipole array.
A Portable Quad for 2 Meters   1.2 MB PDF by R. J. Decesari WA9GDZ from the September 1980 QST.
While this was designed as a backpacking antenna it makes a decent t-hunting / fox hunting antenna that you can store in a hard case made from a piece of plastic sewer pipe with a glued plug on one end and a threaded cap on the other end.
Homebrew Coaxial Dipole for VHF or UHF   1 MB PDF from the July 2009 QST by John E. Portune, W6NBC
Another variation on the coaxial dipole originally intended for base station use for 146, 220 or 440 MHz. Performance is equal to a J-pole, but it is smaller, less obtrusive and easily weatherproofed. Personally, I think John's design could be easily adapted to be used as a mobile no-ground-plane-required antenna.
Garbage In, No Garbage Out   2.5 MB PDF By John E. Portune, W6NBC from the July 1996 issue of 73 Magazine.
Another John Portune article - this one on a homemade VHF cavity.
The Quadrifilar Helix as a 2 Meter Base Station Antenna   3.2 MB PDF By John E. Portune, W6NBC from the October 2009 QST
Yet another John Portune article - this one on a homemade VHF antenna that is equally good on satelites as on mobiles.
Cheap Yagi Antennas for VHF / UHF   404 kB PDF By Kent Britain, WA5VJB for the Clear Lake Amateur Radio Club of Houston, Texas.
This article describes a easy-to-build inexpensive yagi (beam) antenna that can be customized to cover any VHF to UHF frequency. Measurements are given for 144, 222, 420, 432, 450, 902 and 1296 Mhz.
Ground Plane Antennas for 2m, 220 and 440 Mhz   93 kB PDF courtesy of the ARRL
6 meter low-pass filter   285 kB PDF courtesy of the ARRL
A QST article on a homebrew discone   374 kB PDF file from the May 2003 issue
The article describes it as 144 through 450 MHz but it would work just fine at Civil Air Patrol (CAP) frequencies (just plug 139 MHz into the sizing formula) and at GMRS frequencies. Personally, I'd use copper screening, not steel hardware cloth. And discones aren't limited to 2m and up, as this photo of a commercial 25-75 MHz discone will show (photo by WA6ILQ). While it looks like the support mast is on a rooftop air conditioner, it is actually mounted into a tripod base about 20 feet on the far side of the unit. A search of the QST archives shows a 302 kB PDF article on constructing a 40 through 10 meter discone in the July 1975 issue and a follow-up/correction in September.
A Copper Cactus Dual-Band J-Pole Antenna Project   By Tony Petersen N7QVC
Build A VHF/UHF Dual-Band J-Pole Antenna   663 kB PDF By Edison Fong WB6IQN
An article from Feb 2003 QST. In the article Ed specifically says to use Schedule 200 PVC pipe. This is VERY important. If you use anything else, like Schedule 10, 20 or 40, the antenna WILL NOT work. The 200 has a different chemical composition, and anything but 200 will drastically detune the antenna.
Build a Rugged Half-Wave Coaxial Antenna   This is a coaxial sleeve dipole antenna and is the same basic design as the California Highway Patrol uses at some base stations (others use full dipoles, ot even a pair of them).   Courtesy of the Scanner Buff Network   (offsite link)
A homebrew Digital TV Antenna Project   644 kB PDF By Make Magazine
If you are going to make one I suggest you first seal the wood with two or three coats of sealer.
Seven dB for Seven Dollars   844 kB PDF by Nathan Loucks WBØCMT
A homebrew three element two meter beam made from PVC pipe. You might want to use outdoor-rated pipe.
Homebrew vertical antennas for 2m and 6m from PVC pipe   Courtesy J. C. Bishop, VK2ZOI   (offsite link)


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This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.