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R100 repeater and DMK URI interfacing pinouts

This forum is for discussions regarding System Infrastructure and Related Equipment. This includes but is not limited to repeaters, base stations, consoles, voters, Voice over IP, system design and implementation, and other related topics.

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R100 repeater and DMK URI interfacing pinouts

Postby AE5YY » Fri Aug 03, 2018 9:48 pm

It took me a while to get my R100 properly connected to the DMK URI but this is the final pinout that I found successful.

DMK R100
1 -PTT 19 -PTT
8 -COR DET 25 -COR
13 -Ground 6 -GROUND
20 -Ground 17 -Mic Ground
21 -Mic_AC 15 -Spkr High
22 -Left_AC 16 -Mic High

Note: JAUX pin 25 is not tied in to anything and must be modified to carry the COR signal.
See this page for great information on locating COR signal ... rview.html

Interfacing to External Equipment:

Obviously if your station has the DB25 connector and the internal interface components, life will be simpler, assuming you can make do with the signals you have access to. However, since the internal control board does not provide a CW ID, you'll need at least that capability in an external controller. A Com-Spec ID-8 can be connected rather easily to JAux. The following information was provided by Dave N1OFJ:

Com-Spec ID-8 CWID Board To R100 Repeater JAux Interface

ID-8 Signal Wire Color R100 Connection at JAux
Power: J1-1 Red Pin 3: A+
Ground: J1-3 Black Pin 6: ground
Morse Audio Output: J1-9 Violet Pin 5: audio from phone patch
Inhibit Input: J1-7 Blue Pin 23, added to connector
Trigger Input: J1-8 Orange Pin 23, added to connector
PTT Output: J1-2 Grey Pin 4: PTT, also to JAux pin 25
Grey Pin 25, added to connector


PTT output on JAux pin 25 is tied to point "W" on the transmit command board, which will disable the PL encode when grounded. When the ID unit starts sending and grounds PTT, it grounds point "W" as well. Therefore the CWID is sent without PL being transmitted. This configuration is optional.
Trigger input is tied to P4 pin 13 on the receive command board, which is PL Detect and goes active high when receiving. The ID-8 is programmed for an active high on this line. The ID-8 will only ID when it sees on-channel activity. JAux pin 23 is utilized for this task.
Inhibit input is tied to P4 pin 13 as well via JAux pin 23. The ID-8 is programmed for an active high on this line, to inhibit the ID from firing when the receiver is active.

If your R100 is capable of PL, and you want it to do DPL, or vice versa, you'll have to program the radios for carrier squelch and use an external encode/decode unit or a controller that has that capability built-in.

If you only need simple repeater functionality, you can get by with just these signals. Note that this is basically the same as interfacing to a pair of MaxTrac/Radius radios and the signal levels are almost identical.

Audio In
Audio Out

It is certainly possible to wire up directly to the individual radios, either through their DA-15 connectors or to specific points on their command boards. You can peruse the control board schematic and probably find suitable places to attach a bunch of wires and make something work, however everything you need except COR Out can be found on the RJ12 Service Jack, J3. There is one unused pin that can be wired up to provide a COR Out signal, making a very clean interface job possible. Here are the specifics of the signals present on J3. Pin numbers are referenced to the schematic, NOT the circuit board layout.

Pin# Signal Name DCV Notes
1 Not Used / Spare - - - Can be wired for COR Output
2 Headset Audio OUT - - - Fixed level: 55mV/kHz at 400 Hz
3 Push-To-Talk IN +12.7 Active Low: draws 2.5mA
4 MIC HI +9.6 DC Bias present. 50-100mV/kHz
5 MIC LO (ground) 0.0 Audio Ground, tied to pin 6
6 Logic Ground 0.0 Logic Ground, tied to pin 5

Note that there's a DC voltage on the MIC HI signal, used to power the preamp in most Motorola microphones. Most repeater controllers don't expect this, so use a 10uF 16V electrolytic capacitor in series with this line, positive end towards the R100.

COR signals can be found in several places on the control board; I've listed a few below and there are probably more. Use whichever one you want. Note that a lot of the logic on the control board swings from ground up to +13V, not +5V. Measure the signal before using it and use a diode for isolation if necessary. P4 comes directly from the receiver but the connector pins aren't easy to get to. I personally like signals that are active when low, so I'd recommend J6 pin 9 for a COR signal. Make sure your external controller can deal with the high voltage with no signal present.

Signal Name Location With Signal No Signal
Carrier Detect P4, pin 11 0V +13V
PL Detect P4, pin 13 +4V 0V
CSQ+PL Detect J6, pin 9 0V +13V
CSQ+PL Detect U826, pin 11 +13V 0V

Run a wire from the selected pin to J3 pin 1; a feed-through pad near J3 lets you access this pin without removing the control board. Make a cable that plugs into J3 and exits the repeater via any way possible, such as by installing a DB25 into JAux (if empty) or by using spare pins on JAux (if present).

If you foresee the need to control PL Decode (on/off), you'd be best to send both of the Carrier Detect and PL Detect lines to your external controller and let it handle that for you.
That seems easy enough, Should be a quick fix.

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