Motorola Mitrek and MSR2000 Information Index

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Back to Home Information and Modifications for the Mitrek mobile and MSR-2000 station
Compiled by Mike Morris WA6ILQ.

Scroll down or click here for the MSR-2000 station information.

Useful Mitrek Manuals
Click here for instructions on how to order manuals

The list below is from the official Moto list of manuals. Prices listed are August 2007. NLA indicates No Longer Available.

Note the trailing chassis version letter on your radio. The "A" version chassis are unique and have their own set of manuals).

A-revision Mitrek chassis: ( i.e. TnnJJA-nnnnAx where "n" is a number, and "x" may be blank or one or two letters):

Low Band low power (25-50MHz) - T51JJA-nnnnA: 6881037E65 NLA
Low Band high power (25-50MHz) - T71/81JJA-nnnnA: 6881039E70 supplement to the low power manual (i.e. you need both the 37E65 book and the 39E70 supplement for the high power radio - but both are NLA).
High Band low power (136-174MHz) - T43/53JJA-nnnnA: 6881037E70 NLA
High Band high power (136-174MHz) - T63/73/83JJA-nnnnA: 6881039E75 supplement to the low power manual ((i.e. you need both the 37E70 book and the 39E75 supplement for the high power radio - but both are NLA)
UHF low power (406-512MHz) - T34/44JJA-nnnnA: 6881037E75 NLA
UHF high power (406-512MHz) - T64/74JJA-nnnnA: 6881039E80 NLA
(despite the official list showing this as a separate manual, it's actually a supplement to the low power manual (i.e. you need both the 37E75 book and the 39E80 supplement for the high power radio).

B(or later)-revision Mitrek Plus chassis: ( i.e. TnnJJA-nnnnBx, Cx, Dx, Ex, etc ):

Low Band (25-50MHz) - T51/61/71/81JJA-nnnnB, C, D, etc.: 6881045E65 NLA
High Band (136-174MHz) - T43/53/63/73/83JJA-nnnnB, C, D, etc.: 6881045E70 ($30+)
UHF (406-512MHz) - T34/44/54/64/74JJA-nnnnB, C, D, etc.: 6881045E75 ($30+)
800 MHz - all models - T?5JJA-nnnnB, C, D, etc.: 6881045E80 ($117+)

Other:

The 800MHz Mitrek is pretty useless in the amateur world... It uses a single oscillator-multiplier chain for both receive and transmit, and the IF is equal to the repeater offset.... something like the old Pulsar series mobile telephone. You could hack and slash at it and make a 900MHz repeater receiver out of it (it will never work as a 900 MHz mobile) , but there are easier and much smaller radios that work just as well if not better to start with (a 800 MHz Maxtrac comes to mind (and a conversion article is on this web site), or you could use an EFJ 8655 or a Kenwood TK-941 and have a good mobile radio that transmits and receives). In short, the 800MHz Mitrek radios make pretty good doorstops.
If you are going to do a mobile install of a Mitrek, and you can find the installation guide at zero or very low cost then it's worth spending five minutes and looking it over... the Mitrek Installation manual is 6881110E50
The standard control heads and cables are covered in the regular mobile manual. Moto also offered the "Systems 90" control groups for the Micor, Mitrek and Syntor line for mobile installations that needed multiple radios, scanning, MPL (operator controlled multiple PL encoder tones), etc. The "Systems 90" controls are covered in their own manuals:
- Siren / PA....6881108E05 ($11.26)
- Alternate Control Module....6881109E56 ($7.52)
- Channel Scan.....6881102E23 NLA
- Channel Scan.....6881109E58 NLA
- Voice Privacy Adapter....6885900C35-F NLA
- Multi-PL encoder.....(don't have it yet)
- Wildcard....6881102E35 NLA (just a board with momentary and latching switches, configurable by the installer... light bar, siren, dome light, stop light kill, etc).
- The complete module wiring diagram showing how all the units cable together is 6881109E49.

A note on mobile installs... Mitreks make great install-them-and-forget-them radios. Several friends have 4-channel Mitreks stashed in the trunk or under the back seat in their cars, and set up on a couple of local repeaters. A couple of the UHF ones are configured for full duplex, with two antennas, and until you have actually USED a full duplex mobile you don't know what you are missing.

That said, a lot of Mitreks were installed in 18-wheel trucks. Some of those end up on the surplus market wired for positive gound. Because the truck manufacturers (Mack, Kenworth, Peterbilt, etc.) had not standardized the polarity of their tractors when the Mitrek was introduced, it was common for Mitrek cables to be modified in the field from negative to positive ground when a positive ground truck was encountered. As a result, part numbers stamped or printed on cable assemblies may not correctly reflect the polarity for which they are wired. It is best to refer to the negative ground and positive ground cable diagrams in the service manual and compare them to the cable at hand before installation. (thanks to KI4BQQ for the reminder)

Information common to the Mitrek and the MSR-2000

Channel elements for the Mitrek and MSR By Mike Morris WA6ILQ

Mitrek Mobile Radios

RF related Information

A conversion of the Mitrek VHF low band mobile to 6 meters By Wes Nicholas KD3IJ
Another conversion of the Mitrek VHF low band mobile to 6 meters By Tom Herman N1BEC/7
Additional helpful info and manual scans useful to the above two mods By Eric Lemmon WB6FLY
Conversion of the Mitrek VHF high band mobile to repeater service By Peter Harrison AA1PL
Conversion of the Mitrek UHF mobile to full duplex link or repeater By George Zafiropoulos KJ6VU & the Sierra Radio Association
Additional conversion of the Mitrek VHF or UHF mobile Courtesy Doug Spreng W7MCF
Yet another conversion of Mitrek VHF or UHF mobile Courtesy Lou Harris N1UEC (offsite link)
Tuneup of the low band Mitrek (Including coil presets) Courtesy John Clark - KI4AWK
RX-1 RX-2 RX-3 RX-4 RX-5 TX-1 TX-2 TX-3 TX-4 TX-5
Tuneup of the low band Mitrek receiver (Including coil presets) Full width page scan courtesy of by Eric Lemmon WB6FLY
Tuneup of the low band Mitrek transmitter (Including coil presets) Full width page scan courtesy of by Eric Lemmon WB6FLY
Anybody want to scan the tuneup instructions for the High Band Mitrek ???
Tuneup of the UHF Mitrek Receiver Transmitter Courtesy George Zafiropoulos KJ6VU & the Sierra Radio Association

Non-RF related Information

Interfacing the Mitrek mobile radio to your repeater controller (over 175kb of text on over 50 pages, with photos) By Mike Morris WA6ILQ
Includes an introduction, interconnections, COR/COS, repeat audio, Micor squelch, duplex mods, cabling, cooling modifications, and mounting hints.

Karl AK2O and the Spokane Repeater Group have a different take on converting the Mitrek 66kb of text on 17 pages, with photos. (offsite link)
Karls writeup builds on mine and goes much further, with some serious engineering towards optimizing it for packet, or for point-to-point linking.

Mitrek Model and Chassis Numbers Identifying the better Mitrek Model and Chassis Numbers By Mike Morris WA6ILQ

Mitrek HLN4181 PL Board Information (36kb, 10 pages) By Mike Morris WA6ILQ
Technical secrets of the Mitrek HLN4181 reedless PL Board, the TRN-4224 tone element, plus some notes on the HLN-4020 reed board

Mitrek HLN4181 PL Board Schematic 4.5mb PDF of a scan of the schematic sheet from the Mitrek mobile manual

Mitrek HLN4020 dual reed PL Board Schematic and PCB Layout This board will let you encode one tone and decode the other (sometimes called "split tones").

Mitrek HLN4011 Digital PL Board Schematic

Mitrek TLN5730 DPL Two Code Adapter Schematic This board allows the above DPL board to encode one DPL code and decode another, sometimes called "split codes". However this board is not full duplex - it won't let you encode and decode simultaneously, the codes are switched by the PTT line. If you need simultaneous then forget the TLN5730, use the HLN4011 board as the decoder and a Com-Spec DPL board as the encoder.

A better squelch for the Mitrek Using a Micor squelch chip in the Mitrek Courtesy SEITS

The Mitrek bottom plate is a part number HLN4034C. The price in 2006 was about $29.

The Mitrek and the previous mobile designs, the Mocom-70, the Motran and the Motrac) all use a variation on a plug-in relay connector (pin 13 is removed) as a metering socket. Here's a photo of the metering plug, and a diagram of the socket. Photo and diagram courtesy of Eric Lemmon WB6FLY

Mitrek table-top base station ("Super Consolette")

The "Super Consolette" tabletop base station is essentially a desktop cabinet that contains a mobile radio chassis, one of five different power supply chassis, a speaker, control head components, and any options like channel-scan, a metering kit, an alert tone generator, a wireline remote control card, etc.

The documentation on the tabletop base is manual number 6881040E80 (NLA). Note that you need the appropriate mobile radio manual (low band, high band, UHF, 800MHz) to go along with it.

The "Super Consolette" Users Guide is manual number 6881159E69A - click to download the 192 Kb PDF.

Connections to the Mitrek table-top base terminal strips Plus a few other tabletop notes... By Mike Morris WA6ILQ

One of the options on a tabletop base was an internal DC Metering kit. Here's the manual section on the HLN4138A option Scanned by Eric Lemmon WB6FLY

MSR-2000 station

The MSR-2000 is a base or repeater station that is basically a second-generation Micor station control shelf mated to the receiver and exciter sections of a Mitrek mobile, mated to a Micor-derived PA deck. The station shelf has a few upgrades (like a new, more reliable style of card-to-backplane connector), and the RF sections are separate receiver and exciter sections. The control card cage is almost identical to a Micor and many of the notes on the Micor station control shelf are applicable. If you replace the card edge connectors that mate with the Micor backplane with ones made for the MSR you can use many Micor cards in the MSR card cage.

As far as I can tell from the manuals, the model number on the USA-built MSR2000s breaks down as:

Sample model number: C74GSB-3106BTX
Numbers in [ ] refer to notes below.

C 7 4 G S B

Cabinet
Type
[1] Power
Level Frequency
Band Duty
Cycle
[2]
Shielding
[3] Supply
Voltage

C
Compact
Cabinet 5
40-70 watts 3
VHF G
Intermittent R
Base Station
(no duplex shield kit) A
+12vDC

N
No
Cabinet 6
70-90 watts 4
UHF K
Continuous S
Repeater
(has the duplex shield kit) B
120vAC

7
90-120 watts K
120v or 240vAC

Sample model number: C74GSB-3106BTX
Numbers in [ ] refer to notes below.

3 1 0 6 B T X

Squelch
Type
[4] Channel
Deviation
[5]
Frequencies
Control
Version
Configuration
(?)

1
Carrier 0
15 KHz 0
Single Frequency 3
Local Only A A
(?) X
(?)

3
PL 1
5 KHz 3
Two Frequency 5
DC Wireline B B
Base

6
DPL 9
Four Frequency 6
Tone Wireline C D
(?)

D T
Repeater

Table Notes:

An "N" is a very rare beast, as they were special order. It was actually cheaper (and quicker) to order a "C" and remove it from the cabinet (which could be sold to someone else).
There is no practical way to change an intermittent duty cycle radio to a continuous short of replacing the power supply and the PA deck.
There is no practical way to convert a base to a repeater with full performance as the repeat duplex kit includes a different backplane, a different receiver, a different exciter and a different PA deck, plus some additional metal shield plates. This is not to say that you can't convert a base station into a repeater, just that something designed and built to run full duplex from the factory is better.
Changing squelch types involves changing out the squelch card (or adding one if you have a carrier squelch station).
A "0" is a very rare beast as the market for wideband radios is very limited. It was a special order for the broadcast industry as some stations still have VHF and UHF remote pickup channels.

Station Notes

There are at least three vhf high band power amplifier models... the 110 watt inttermittent duty power amplifier works pretty well at about 60 watts continuous duty in a well vented and cooled radio vault, but you need to add fans, and if they die so does the power amplifier. The continuous duty rated amplifier deck will do continuous duty only if it's in the proper band segement for which it was built. And the range change/conversion parts are no longer available.

An easy to tell if you have the intermittent or the continuous duty amplifier: if yours has heatsink fins all the way across the rack panel, you have the continuous duty PA. If the fins only go about halfway across, it's the intermittent duty PA.

This is the continuous duty power amplifier

This is the intermittent duty power amplifier

If you have the intermittent duty amplifier, use two fans, and mount a Klixon thermostat to the hot end of the heat sink, and wire it such that when activated it turns on the spare fan and also trips an alarm on your repeater controller (maybe the courtesy tone changes to a morse "H" (for Hot) and the MCW ID gets a "[space]OT" for OverTemp added to the end). Or something.

The early "A" versions of the PA would fail if you looked at it cross-eyed. The B version was much improved and could better deal with reactive loads and heat problems. If you are going to buy an MSR, you really, really want to avoid the "A" version PA decks.

UHF PA's were built in three band segments. There's the low split 406-430 MHz version, there's the 450 to 490 MHz range, and there's the high range 485-512 MHz range. And there is no way of changing a 406-430 MHz or a 485-512 to 450-490.

Note that the MSR-2000 station does not have a built in speaker - it's in the test set. You can connect a regular 8 ohm mobile speaker to the unit, however (see K4HAL's writeup for the information).

The local speaker volume control is a screwdriver adjust accessed through a hole in one of the control card metal endpieces. One very common modification is to replace that potentiometer with one that has a real shaft and a regular knob. The real pot can be mounted into the hole in the metal front plate (which you can enlarge if necessary), then run three jumper wires from the pot terminals to the circuit board where the original pot used to be. If the new volume control is added carefully you'd think it was Moto stock.

A regular Mitrek / Micor / Syntor mobile microphone can be plugged into the front of the station audio card to provide local keying and local microphone audio. The station audio card has the microphone audio mix function built in. Just mount a mic clip to the unit and you are done. Since the standard Moto mic has a set of normally open switch contacts in series with the element you won't be picking up any in-cabinet noise.

The multi-PL tone decoder module for the card cage is the TRN5329x (where x is the A or B version). When used in the stock repeat shelf, this card allows the repeater to respond to up to four additional tones on the input, ORed on the card to the single status line that tells the shelf that the PL tone has been decoded. With the MSR configured as a full duplex base station, and cabled to a repeater controller, it can feed the repeater controller inputs and tell it which tone is being received. One common use of multiple PL decode is on a club machine, with the first tone (for example, 100 Hz) listed in the local repeater directory, and the second (perhaps 146.2 Hz) used by club members. The 100 Hz tone would be programmed for just local repeat, and the 146.2 Hz would alow autopatch and other system toys. Click here for a photo.

So if you are looking for a used MSR the ideal radio is a KSB-31xxBT, CT or DT series, and a GS series will do just fine at reduced power and a with a fan. And if you end up with a GS series you really want to mount a second (backup) fan controlled by a thermostat.

Useful MSR-2000 Manuals Click here for instructions on how to order manuals

6881061E40 = Control and audio (no RF), still available from Motorola for about $57
6881061E50 = VHF RF, Power Supply, and Accessories Manual (was about $52 but is now NLA i.e. not available from Moto... try your local 2-way shop or eBay).
6881061E55 = UHF RF (yes, if you have a UHF station you will need the VHF book just for the power supply and accessories), (was about $40 but is now NLA).
6881062E47 = Battery Charger Power Supply Option C28AN (you only need this if your station has this option) NLA
6881114E65 = UHF Preamplifier TLE2403 (you only need this if your station has this option, and frankly AngleLinear makes a much better preamp) NLA
6881114E66 = VHF Preamplifier TLD2611A (ditto) NLA

Prices quoted above are Moto "NSO" Pricing ("National Service Organization") - the prices that moto charges their service shops. Pricing to the public may be higher.

Articles:

Alignment of the MSR-2000 station UHF receiver 176kb PDF document
Alignment of the MSR-2000 station UHF transmitter 1.2mb PDF document
Conversion of an MSR-2000 station to an amateur repeater   By Henry Wingate K4HAL
A status display for the MSR-2000 station   By Henry Wingate K4HAL
MSR-2000 test set (TRN5079 and TRN5080) - Photo Schematic and parts list courtesy of David Stanford K7IOU
Another conversion of an MSR-2000 station to an amateur repeater   By David Stanford K7IOU (offsite link)
Conversion of an MSR-2000 station for the WØDOD repeater   By Nate Bargmann, NØNB
There is one interfacing technique that we don't have an article on... it was described to me over dinner a few years ago...
Take a card like a timeout timer card, strip it, mount an RLC-MOT (and optionally a PL tone (or DPL code) decoder) on standoffs, then mount a DB15 into the front sheet metal. Slide that interface card into the squelch gate slot. Use the DB15 to connect the repeat audio, COR and PL decode signals to an external controller. The same card can inject repeat audio from the controller into the backplane.
The controller interface card hadles the repeater in normal use, then if the outside controller takes a dive you can unplug this interface board and plug a regular (unmodified) squelch gate card in to get the system back on the air. Using a squelch gate card does not provide an identifier, but does give you a good emergency kerchunk box (a very basic repeater). The different sounding squelch tail and different carrier delay timer duration will tell your users that the backup "control" system is in place and that they need to voice ID the system.
Modifications to the MSR-2000 cards by VE6SBS for the VE6NHB repeater Original article, offsite link
I suggest you read the entire article first.

Here are the schematics of his modified MSR-2000 card cage and cards: (all are pdf files)
The modifications on the schematics are not visible - the modified prints look just like original Moto schematics - you will have to compare them to the originals to determine the changes.
     Backplane wiring 5.1mb
     TLD9232 exciter 555kb
     TRD6182 receiver 618kb
     TRN5069A R1 Audio Squelch 442kb
     TRN5075A PL encoder decoder 423kb
     TRN5321A Station Control 343kb
     TRN5331B Squelch Gate 509kb
Documentation on the TLN6721CDX TX Alarm card - provided by A. Nony Mous (see Documentation page for photos of the card)
This card was designed for the Canadian Provincial Police system of over 600 MSRs that was decomissioned about 2002. These were a mix of continuous and intermittent duty 136-150 MHz stations that were deployed in shelters that had battery backup and local AC generators, and an adjacent radio tower, with all of the sites linked by microwave shots. The relay contacts on this card were integrated into the site alarm system. There is a downloadable 4-page PDF containing a theory writeup and schematic linked to this page.
Documentation on the TLN640CDX IDer card - provided by www.radiowrench.com Photo of the card
If you have an MSR that uses this IDer it's MUCH easier and more flexible to ignore / remove this card and use a external repeater controller like an NHRC, Scom, etc. as this card uses an almost-impossible-to-get 32x8 one-time-burnable PROM chip (yes, 256 bits) that is almost pure unobtanium, plus almost nobody can burn them any more. Yes, you could build a socket adapter and plug in a modern PROM chip, but since FCC Rules require you to be able to remotely switch the repeater on and off you need a real repeater controller anyway... and you can buy a decent one for under US$160 (the NHRC-4)
       Cover page (info on the donor)     Pg1 440kb     Pg2 51.4kb     Pg3 43.4kb     Pg4 93.8kb     Pg5 33kb
       Pg6 55kb (programming chart)     Pg7 40.5kb (parts list)     Pg8 1.32mb (schematic right half)     Pg9 1.25mb (schematic left half)
       Pg10 1.35mb (PCB layout pg1)     Pg11 1.4mb (PCB layout pg2)        All of the pdfs in one zip file for easy downloading

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Motorola® is a registered trademark of Motorola Inc. Image used with permission.
Channel Element, Mitrek® and MSR-2000® are registered trademarks of Motorola Inc. So there!

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.

Sample model number: C74GSB-3106BTX Numbers in [ ] refer to notes below.
C	7	4	G	S	B
Cabinet Type [1]	Power Level	Frequency Band	Duty Cycle [2]	Shielding [3]	Supply Voltage
C Compact Cabinet	5 40-70 watts	3 VHF	G Intermittent	R Base Station (no duplex shield kit)	A +12vDC
N No Cabinet	6 70-90 watts	4 UHF	K Continuous	S Repeater (has the duplex shield kit)	B 120vAC
	7 90-120 watts	4 UHF	K Continuous	S Repeater (has the duplex shield kit)	K 120v or 240vAC

Sample model number: C74GSB-3106BTX Numbers in [ ] refer to notes below.
3	1	0	6	B	T	X
Squelch Type [4]	Channel Deviation [5]	Frequencies	Control	Version	Configuration	(?)
1 Carrier	0 15 KHz	0 Single Frequency	3 Local Only	A	A (?)	X (?)
3 PL	1 5 KHz	3 Two Frequency	5 DC Wireline	B	B Base
6 DPL		9 Four Frequency	6 Tone Wireline	C	D (?)
6 DPL		9 Four Frequency	6 Tone Wireline	D	T Repeater