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The information presented in this section is copyrighted by repeater-builder (the author's/owner's copyright, if any, supercedes it).

There are other good articles on the Technical Info page

Build an Isolated Tee Sampler for a Bird 43 Wattmeter Build an IsoTee Sampler for the Bird from a blank slug! By Kevin Custer W3KKC

Build your own Iso-Tee Build an Iso-Tee from an ordinary T-adapter. By Ted Bleiman K9MDM

A Photo Tour of a Bird Wattmeter Element Ever wonder what's inside one of those elements? By Robert W. Meister WA1MIK

Duplexer coupling loops and how they affect performance An analysis of factory-built vs home-built loops. Ongoing research (a work-in-progress) by Kevin Custer W3KKC

PL-CG (CTCSS) Filter Construction Projects Build several PL (CTCSS) Filters!

Audio Buffer and De-Emphasis circuit Use this circuit after a repeater receiver to de-emphasize the audio going to your controller. By Lou Harris N1UEC (offsite link)

Pre- and De-Emphasis circuit component values Pre-calculated common component values. By W9ZGS.

A Poor Ham's Deviation Meter A theory and practice article on measuring deviation of FM transmitters, by Robert W. Meister WA1MIK

A 13.8v 40a switching power supply by Manfred Mornhinweg XQ2FOD (from Dec 1998 and Jan 1999 QST magazine) 1.2MB PDF file
This switcher is RF-quiet from 50 Khz to over 40 Mhz and is over 85% efficient (and it beats the pants off the GE Mastr II ferroresonant supply). Note that this project appeared in the ARRL Handbook with several resistors shown with incorrect values. The schematic in this PDF is correct.

The Repeater Builder's Friend A device to help to you fix your repeater or program your controller by Matt Krick K3MK.

Build Youself a Service Monitor? Well, sort of. By Tom Alldread VA7TA A simple deviation monitor circuit used with a scanner receiver.

Multi-Element Exposed Dipole for 2 Meters A good exposed Four-Bay Dipole Array construction project.

Someone say "6 meter duplexer" ? A comprehensive conversion of a lowband pass cavity to BpBr by Jeff DePolo WN3A.

Heliax 6 Meter Filter construction article A comprehensive filter construction article using 1-5/8 inch hardline by Robert W. Meister WA1MIK

Build a telephone line filter that doubles as a lightning protector A phone line filter and protector by Kevin Custer W3KKC

A Phone Line Busy Sensing Circuit By Monte Smith, WDØDIR, from ACC Notes, April, 1986. If you need to share a phone line between your home and a repeater, here's how.

Build an audio buffer amplifier Kick the audio in the butt by Kevin Custer W3KKC

Build a set of CATV Hardline Matching Stubs by Kevin Custer W3KKC

Retuning a Stationmaster type antenna By Jim Barbour WD8CHL

Build a good quality GaAs FET Preamp For 2 meters, 220 and 440 by Kevin Custer W3KKC

Build a Two Channel Signal to Noise Voter From the WB2WHC article in October 1992 QST.

Omni-Gain Collinear Repeater Antenna Construction Project A great 144 to 1300 MHz antenna project - and there are followup articles on the Antenna Systems page at this web site.

Use an Astron power supply remotely? Look here! Don't run to the repeater site to reset the Astron anymore! (scroll down to the Reset Circuits)

Build a set of Band Pass-Band Reject Two Meter Duplexers From the W1GAN article in the July 1972 QST

Basic Stamp 1 and 2 Repeater Controller construction projects Cheap controllers by Roger Cameron NØYOX.

Audio Limiter for NBFM A hard audio limiter like used in broadcast audio.

A Push To Talk Delay Circuit For ACC controller users

A COR Hang Timer Circuit A simple controller of sorts

Build a COS Detector Circuit For creating a COS signal on radios that don't have one.
This is a VOX circuit that uses a FET as the input amplifier to avoid loading down the source.

The Jet Propulsion Labratories "Smart VOX" By Randy Hammock KC6HUR and Jan Tarsala WB6VRN
For creating a COS signal from a radio that doesn't have one. This circuit was developed to control the retransmission of NASA Select audio over JPL's W6VIO repeaters.

Repeater Controller Construction Projects Build Controllers and stuff for them!

A Crystal Heater construction project Make that crystal stable... By Bob Dengler NO6B

A Simple Repeater Fan Controller an 18kb PDF file By Robert Shepard KA9FLX

A Repeater Fan Controller using a 556 IC 18kb PDF file This is a followup to the above with a modification to a single 556 chip. By George Henry KA3HSW

An Audio Equalizer for Communications Use 234 KB PDF file This five-band audio equalizer was originally designed for use at a multireciever site (a voting system hub). By Robin Humbolt WA4TEM, originally published in the May 1990 QST

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 simple Echolink interface Easily constructed with about $10 in parts from Radio Shack. Should work with any radio. Courtesy of Matt Krick K3MK
If you have to use speaker audio from a radio that has a floating audio output (i.e. both speaker leads are above ground, like many Kenwoods, Icoms, Yaesus, all Maxtracs, all Radius mobiles, all GM300s and all CM series) then you may need to add a small audio transformer between the radio speaker audio output and the sound card input. The Triad TY145 transformer works well for this and they are under $4 from Mouser Electronics as I write this in early 2012 (p/n:553-TY145P). I'd also add an 8 ohm 1 watt resistor in parallel with the radio output.

A purpose-built Motrac Metering set I needed to tune a Motrac-based Compa-station but had no official metering set. I had a meter; I bought everything else. You can modify the design to suit your needs. By Robert W. Meister WA1MIK

A VHF/UHF/LINK repeater interface/controller 239kb PDF file. This is a set of nearly identical schematics for circuitry used to provide cross-band inter-agency communications.

A simple audio mute circuit 20kb PDF file. If you're using discriminator audio and need to mute it, this circuit will do the job. Sent anonymously to repeater-builder.

A Tone Beep Keyer for Repeaters 98kb PDF file. Obtain an Audible Indication of Off-Frequency Operation. Originally by Art Gentry W6MEP. Reprinted from May 1974 QST.

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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.

	Build an Isolated Tee Sampler for a Bird 43 Wattmeter Build an IsoTee Sampler for the Bird from a blank slug! By Kevin Custer W3KKC
	Build your own Iso-Tee Build an Iso-Tee from an ordinary T-adapter. By Ted Bleiman K9MDM
	A Photo Tour of a Bird Wattmeter Element Ever wonder what's inside one of those elements? By Robert W. Meister WA1MIK
	Duplexer coupling loops and how they affect performance An analysis of factory-built vs home-built loops. Ongoing research (a work-in-progress) by Kevin Custer W3KKC
	PL-CG (CTCSS) Filter Construction Projects Build several PL (CTCSS) Filters!
	Audio Buffer and De-Emphasis circuit Use this circuit after a repeater receiver to de-emphasize the audio going to your controller. By Lou Harris N1UEC (offsite link)
	Pre- and De-Emphasis circuit component values Pre-calculated common component values. By W9ZGS.
	A Poor Ham's Deviation Meter A theory and practice article on measuring deviation of FM transmitters, by Robert W. Meister WA1MIK
	A 13.8v 40a switching power supply by Manfred Mornhinweg XQ2FOD (from Dec 1998 and Jan 1999 QST magazine) 1.2MB PDF file This switcher is RF-quiet from 50 Khz to over 40 Mhz and is over 85% efficient (and it beats the pants off the GE Mastr II ferroresonant supply). Note that this project appeared in the ARRL Handbook with several resistors shown with incorrect values. The schematic in this PDF is correct.
	The Repeater Builder's Friend A device to help to you fix your repeater or program your controller by Matt Krick K3MK.
	Build Youself a Service Monitor? Well, sort of. By Tom Alldread VA7TA A simple deviation monitor circuit used with a scanner receiver.
	Multi-Element Exposed Dipole for 2 Meters A good exposed Four-Bay Dipole Array construction project.
	Someone say "6 meter duplexer" ? A comprehensive conversion of a lowband pass cavity to BpBr by Jeff DePolo WN3A.
	Heliax 6 Meter Filter construction article A comprehensive filter construction article using 1-5/8 inch hardline by Robert W. Meister WA1MIK
	Build a telephone line filter that doubles as a lightning protector A phone line filter and protector by Kevin Custer W3KKC
	A Phone Line Busy Sensing Circuit By Monte Smith, WDØDIR, from ACC Notes, April, 1986. If you need to share a phone line between your home and a repeater, here's how.
	Build an audio buffer amplifier Kick the audio in the butt by Kevin Custer W3KKC
	Build a set of CATV Hardline Matching Stubs by Kevin Custer W3KKC
	Retuning a Stationmaster type antenna By Jim Barbour WD8CHL
	Build a good quality GaAs FET Preamp For 2 meters, 220 and 440 by Kevin Custer W3KKC
	Build a Two Channel Signal to Noise Voter From the WB2WHC article in October 1992 QST.
	Omni-Gain Collinear Repeater Antenna Construction Project A great 144 to 1300 MHz antenna project - and there are followup articles on the Antenna Systems page at this web site.
	Use an Astron power supply remotely? Look here! Don't run to the repeater site to reset the Astron anymore! (scroll down to the Reset Circuits)
	Build a set of Band Pass-Band Reject Two Meter Duplexers From the W1GAN article in the July 1972 QST
	Basic Stamp 1 and 2 Repeater Controller construction projects Cheap controllers by Roger Cameron NØYOX.
	Audio Limiter for NBFM A hard audio limiter like used in broadcast audio.
	A Push To Talk Delay Circuit For ACC controller users
	A COR Hang Timer Circuit A simple controller of sorts
	Build a COS Detector Circuit For creating a COS signal on radios that don't have one. This is a VOX circuit that uses a FET as the input amplifier to avoid loading down the source.
	The Jet Propulsion Labratories "Smart VOX" By Randy Hammock KC6HUR and Jan Tarsala WB6VRN For creating a COS signal from a radio that doesn't have one. This circuit was developed to control the retransmission of NASA Select audio over JPL's W6VIO repeaters.
	Repeater Controller Construction Projects Build Controllers and stuff for them!
	A Crystal Heater construction project Make that crystal stable... By Bob Dengler NO6B
	A Simple Repeater Fan Controller an 18kb PDF file By Robert Shepard KA9FLX
	A Repeater Fan Controller using a 556 IC 18kb PDF file This is a followup to the above with a modification to a single 556 chip. By George Henry KA3HSW
	An Audio Equalizer for Communications Use 234 KB PDF file This five-band audio equalizer was originally designed for use at a multireciever site (a voting system hub). By Robin Humbolt WA4TEM, originally published in the May 1990 QST
	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 simple Echolink interface Easily constructed with about $10 in parts from Radio Shack. Should work with any radio. Courtesy of Matt Krick K3MK If you have to use speaker audio from a radio that has a floating audio output (i.e. both speaker leads are above ground, like many Kenwoods, Icoms, Yaesus, all Maxtracs, all Radius mobiles, all GM300s and all CM series) then you may need to add a small audio transformer between the radio speaker audio output and the sound card input. The Triad TY145 transformer works well for this and they are under $4 from Mouser Electronics as I write this in early 2012 (p/n:553-TY145P). I'd also add an 8 ohm 1 watt resistor in parallel with the radio output.
	A purpose-built Motrac Metering set I needed to tune a Motrac-based Compa-station but had no official metering set. I had a meter; I bought everything else. You can modify the design to suit your needs. By Robert W. Meister WA1MIK
	A VHF/UHF/LINK repeater interface/controller 239kb PDF file. This is a set of nearly identical schematics for circuitry used to provide cross-band inter-agency communications.
	A simple audio mute circuit 20kb PDF file. If you're using discriminator audio and need to mute it, this circuit will do the job. Sent anonymously to repeater-builder.
	A Tone Beep Keyer for Repeaters 98kb PDF file. Obtain an Audible Indication of Off-Frequency Operation. Originally by Art Gentry W6MEP. Reprinted from May 1974 QST.