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Sigtronics Transcom II with TK-790

Caboverbob

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Greetings. I have a TK-790 that is used in my railroad speeder on railroad frequencies that I would like to connect to a Sigtronics Transcom II intercom system for communication with passengers and other operators. Many of use this same intercom, and I have mine currently set up with a Moto MCS2000 thru a custom interface box built by a former Moto engineer. Hoping that someone can offer some insight into something commercially available, or will I need to build a custom box like the one for my Moto ?

 

n7maq-1

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Most likely the TK-790 will have to have a 0 Ohm resistor (R641 moved to R640) moved to allow for external mic audio. Then remove the MCS2000 DB25 F/M connector and hook the wires up to a DB25 M for the Kenwood. Below are the pinouts. There should only be 6 or 7 wires to move.

MCS 2000
1 SPKR+
2 INT SPKR+
3 SPKR-
4 GND - Digital Ground
5 BUSY
6 BUS+
7 I/O 6 - Hub/Monitor
8 I/O 5 - Car Radio Mute/Carrier Detect
9 EMERGENCY
10 GND - Analog Ground
11 RX HI:FIL AUDIO - Discriminator Audio Out
12 AUX RX IN2
13 MIC IN - TX Audio IN
14 SW B+ - +12 VDC When Radio On
15 IGNITION
16 I/O 2 - Horn/Lights
17 RESET
18 BUS-
19 SCI RX DATA
20 I/O 4 - Not Used
21 I/O 3 - PTT (GND=PTT)
22 RSSI OUT
23 EXTERNAL MIC IN
24 AUX TX IN2
25 BUFFERED DISCRIMINATOR - Univ IO Out


TK-790
1766078366148.png
 

ramal121

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That intercom unit does not easily port over to LMR type radios. If you needed a custom interface box for the MCS2000 I would think this would be required for a Kenwood radio also. Any way to take a photo of the guts of the interface to try and guess how complex it would be?

If anything, DO NOT try to connect the headphone input to the speaker lines of the 790. You can damage the audio PA of the radio by doing so. Maybe damage to the intercom. There are other ways to get receive audio to the intercom.

Not impossible, just needs certain considerations.

I think I speak for everyone when I say. We would love to know more about Railroad Speeders.
Zoom zoom. Great fun!

speeder.jpg
 

RFI-EMI-GUY

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If anything, DO NOT try to connect the headphone input to the speaker lines of the 790. You can damage the audio PA of the radio by doing so. Maybe damage to the intercom. There are other ways to get receive audio to the intercom.
Yeah nearly every mobile radio or scanner now uses BTL (Bridge Tied Load) audio output amplifiers. These want to see a balanced load like a speaker or a transformer. If you short one of the speaker leads to ground or A+ you will possibly damage the radio. At best you will have severe distortion. Verify before you build.

1766194102213.gif
 

kd4efm

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I think I speak for everyone when I say. We would love to know more about Railroad Speeders.
LOL I actually have a Fairbanks-Morse S-1 in my backyard that would love a rebuild and home.
but for another thread.
 
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RFI-EMI-GUY

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LOL I actually have a Fairbanks-Morse S-1 in my backyard that would love a rebuild and home.
but for another thread.
I do some SCADA work for the South Florida Water Management District. Their big pump houses, which "slosh" rainwater back and forth in the Everglades, have huge F-M engines salvaged from WW2 ships. In fact there are plaques on the wall denoting which engine came from which ship. They had to rework them for EPA which entailed installing huge catalytic converters and eventually new superchargers due to some problem with the catalytic convertor conversion.
 

RFI-EMI-GUY

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AK9R

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Man, you guys can sure derail a thread.
Yeah, and let's get back on topic.

Installing a TK-790 in a speeder--on topic.

What engine your speeder has--off topic.
 
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