Motorola MTR2000 Repeater
The MTR2000 is a Motorola repeater rated for 100% duty cycle. What follows is some basic information as I figure out what's what.
The model numbers, e.g., T5544A or T5766A, do not communicate band information! They seem to just tell you that it's an MTR2000.
Also, a lot of people seem to take the front panel off and use the information on the sticker on the left to describe their eBay ads. That's the information on the power supply. Some of the FRUs (Field-Replaceable Units) can be used to figure out the band lacking other indications. What's below is stuff I've gathered from perusing some eBay listings over time; http://www.repeater-builder.com/motorola/mtr2k/mtr2000-frus.html is perhaps the definitive list.
Be aware that there are MTR2000s that shipped with _only_ a receiver, listed as satellite receivers. They look the same and even appear to have the PA heatsink, but with no connector since there's no actual transmitter or PA. The rear label will show only an RX FCC ID, no TX one. T5769A (UHF) is one model number; is that meaningful?
Bands
VHF
On the VHF side, the FCC type-acceptance ID is the _same_ between the splits. The low-power (132-174) transmitter is ABZ89FC3785; the high-power (132-154 _or_ 150-174) is ABZ89FC3786.
| Bandsplit | Power | Model | RX FCC ID | TX FCC ID | 2019 eBay price |
|---|---|---|---|---|---|
| 132-154 MHz | 25-100 Watts | T5766A | ABZ89FR3787 (not unique) | ABZ89FC3786 (not unique) | rarely seen |
| 150-174 MHz | 110 Watts | ABZ89FR3787 (not unique) | ABZ89FC3786 (not unique) | $1k - $1,700 |
FRUs
Please note that some FRUs cover the whole bandsplit, but that does _not_ mean the entire repeater does. For example, a 150-174 MHz repeater may have the 132-174 MHz exciter and receiver.
- VHF receiver FRUs:
- TRD6431F, TRD6431G, TRD6431J - with preselector
- VHF exciter FRUs:
- TTD6301E, 132-174 MHz
- PA:
- TTD1792: TTD1792B (150-174?)
UHF
| Bandsplit | Power | Model | RX FCC ID | TX FCC ID | 2019 eBay price |
|---|---|---|---|---|---|
| 403-470 MHz | 40 Watts | T5731A, T5544A | ABZ89FR4813 | ABZ89FC4811 | $695 (no preselector) |
| 403-435 MHz | 25-100 Watts | meh | ABZ89FR4813 (not unique) | ABZ89FC4812 (not unique) | |
| 435-470 MHz | 25-100 Watts | ? | ABZ89FR4813 (not unique) | ABZ89FC4812 (not unique) | $1,275 (preselector) |
FRUs
- Receiver
- CLD1230A: UHF receiver
- TRX4014: TRX4014A, TRX4014N
- Exciter
- CLE1450A (on a 435-470 radio)
- TTX4014 (403-470?)
- Control board
- CLN1465B (not sure if this is band-specific?)
- Power Amp
- CLE1307A, CLN1229A: 100W 435-470 PA
800 MHz
| Bandsplit | Power | Model | RX FCC ID | TX FCC ID | 2019 eBay price |
|---|---|---|---|---|---|
| 806-870 MHz | 20-75 Watts | T5544A | ABZ89FR5786 | ABZ89FC5785 | ? |
FRUs
- Receiver
- TRF6631: TRF6631A, TRF6631L
- Exciter
- TTF6521: TTF6521A
Non-band-specific cards
- Wireline card
- CLN6698D
- Wireline interface board
- TTN5067D, TTN5067E
- Power supply
- DLN6624A
- DLN6707A (for 100W models)
- Station control board
- CLN1465: CLN1465A11
DMR
The MTR2000 is an analog repeater, and has no native support for DMR or any other analog mode. (The MTR3000 _does_ support DMR in some configurations, it seems.)
Using something like the MMDVM, you could build your own. But I've just learned of the STM32-DVM-MTR2K, which is an MMDVM board that sits in the card cage!
Going Out of Band
These are often described as not being capable of taking out of band. And, indeed, these are not like some radios where a quick CPS hex-edit lets you program out of band where everything works just fine.
The main problem is with 100-Watt repeaters, which only cover part of the band. It turns out that the limit is the PA only; the receiver and exciter both cover the full band.
http://www.kc9umr.com/?p=151 describes getting one of the 150-174 MHz models down into the ham band. The correct fix is to replace the circulator, change out the resistors to the correct values, and then realign the thing. From some posts I've seen, for taking a 150-174 MHz repeater down to 146 MHz or so, simply changing the resistors seems to work acceptably.
What I am seeing is that you need to change out R4560 and R4564, which are how the repeater senses which PA is attached. The following values are known:
- 1.5kΩ: 150-174 MHz, 100W
- 4.7kΩ: 136-174 MHz, 40W
- 15kΩ: 132-154 MHz, 100W
https://communications.support/threads/3520-MTR-2000-VHF-100W-out-of-band-operation seems to have some more information, and http://www.repeater-builder.com/motorola/mtr2k/vhf-out-of-band/mtr2000-vhf-out-of-band.html goes into a lot of detail. This is clearly not something for people like me with poor soldering skills.