OT: Looking for control board for Kenwood TM-742A
I'm not one for off-topic posts I know, but there are also a lot of resources here...
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I'm looking for a replacement board to get a TM-742A going again. I need the board that has the battery on it. You can guess why I need it.
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Anyone have any parts or parts radios about? Please drop me an off list email to my callsign at aol dot com.
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Thanks,
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Chris/KF6AJM
--
Chris Baldwin, CETSr. (KF6AJM)
Trustee - MetroNET Cal. Intertie (KB3PX)
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Re: Suggestions for service monitor
Try a LibreVNA. They are both a VNA and Spectrum Analyzer that run though USB to a computer.?
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Rob VK5TRM
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Re: Kenwood NXR 810 repeater
The only thing you have to be careful of with the six-pin versus the eight pin is make sure that the repeater is off when you plug in. That's because there is plus 12 volts at the 8-pin jack that powers the cable.? Weird I know but it is.. Kenwood TAC told me this years ago.. When using the six pin plug on the TKRs and other radios that have it, you do run the risk of shorting 12 volts to ground and opening a zero ohm resistor inside behind the front panel. Then you can't program! I know of one TKR 750 that I ran across that had that done. Had to use the DB25 in the back. Once you're plugged in, you can turn the repeater on and program away.?
At 4/6/2025 06:19 AM, you wrote:
I prefer to use the 8 pin
modular cable.?? That allows me to go to a site
and make programming changes from the front panel of the repeater and
not have to go in the back and possibly remove a db-25 that connects to
something else like a controller.?? The less time I spend in the
back of
the rack, the less time I have to accidentally disconnect something
else.
Joe, K1ike
Same here.? But my programming cable is 6 pin (6P6C) yet it plugs
into the 8P8C socket on the TKR-850 & communicates just fine.? I
think I used the same cable on the NXRs.
Bob NO6B
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Re: Kenwood NXR 810 repeater
At 4/6/2025 06:19 AM, you wrote:
I prefer to use the 8 pin
modular cable.?? That allows me to go to a site
and make programming changes from the front panel of the repeater and
not have to go in the back and possibly remove a db-25 that connects to
something else like a controller.?? The less time I spend in the
back of
the rack, the less time I have to accidentally disconnect something
else.
Joe, K1ike
Same here.? But my programming cable is 6 pin (6P6C) yet it plugs
into the 8P8C socket on the TKR-850 & communicates just fine.? I
think I used the same cable on the NXRs.
Bob NO6B
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Re: 220Mhz ACSB amplifier
Ken,
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We had boxes of 50 watt 220 linear amps in a cabinet down here at Garmin in Salem never touched for 15 years.
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When I retired in January of this year I heard that they tossed everything in a recycling box and given to a recycler out in Independence? Or..
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Re: Arcom RC210 Not Responding to COS Input on Any Port (Confirmed Good Repeaters)
First thing to check for is when you power the controller on you should see one of the LEDs flash rapidly, which I recall was one of the COR LEDs then after about 5-10 seconds that should stop and then all three of the PTT LEDs should light and you will get the power up sign on message usually something like "R C 210 V something point something" "Ready". The PTT LEDs should then go out.
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If that doesn't happen, check your power input connections, and make sure the front panel LED enable switch is on which you can check it with an ohm meter, needs to be shorting the jumper header or you can put a jumper on the LED header JP13.
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If that is all working, set the COR and PL jumpers to the 1-2 position.? You can then ground the respective pins of the DB-9 connector, Pin 2 for PL, Pin 7 for COR.? You should get an LED light on the front panel per the respective input, if not check the diodes at D16-D21. Make sure the polarity is correct.? There is also they were mixed up with the Zener diodes since they look almost identical,? check if you can see 5231 written on them.
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You can also set the COR and PL jumpers to 2-3 and use a known good 5-12 volt power supply to see if you can get the LEDs to light. That will prove the positive going transistors are good.
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Re: Arcom RC210 Not Responding to COS Input on Any Port (Confirmed Good Repeaters)
Responded to privately
At 07:02 AM 4/6/2025, you wrote:
Hi all, Re-posting this as
for some reason our first post never made it through:?
We're running into a major issue with a recently assembled RC210 —
it?�?s not responding to valid COS signaals or PTT (besides manually
triggering it) on any of the three ports, even though the connected
repeaters are confirmed working.
We're interfacing with both a Motorola XPR8300 and a Kenwood TKR-740 —
and here?�?s what we?�?ve conffirmed:
Repeater Tests (XPR8300 & TKR-740)
- COS (Pin 21 / GPIO3 on XPR8300): Drops from ~4.66V to ~0.53V when
receiving a signal (confirmed using XPR Pin 16 as GND).
- PTT (Pin 17 / GPIO1): Keys repeater successfully when pulled
low.
- We repeated these tests using a Kenwood TKR-740 repeater with the
same result — valid COOS signals present and working as expected.
- All measurements taken directly at the repeater accessory
connectors using a multimeter. RC210 was disconnected for isolation
testing.
RC210 Fails to Detect COS
- All jumpers set per manual (e.g., JP2 = 1–2 for Active Low input on
Port 1).
- GND is confirmed clean and consistent across DB9 pins 6, 8, and
9.
- Simulating COS by shorting DB9 Pin 7 (COS IN) to Pin 6 (GND)
results in:
- No COS LED
- No PTT trigger
- No voltage drop on PTT OUT (Pin 3)
- However, manually shorting DB9 Pin 3 to GND causes the PTT LED to
light and voltage to drop to 0V — confirming the RC210's PTT output
circuitry is working corrrectly. ** All three ports, no automatic PTT
detection either **
- Same behavior confirmed on Ports 1, 2, and 3 — no COS detection on
any port.
We had this unit assembled by Mr. Ken at Arcom, and he sent it back to us
in a timely manner, we also emailed him our findings as well, hopefully
he can help us with this.
?
Additionally, during troubleshooting the board, we found several
clipped component leads left between pads and vias. We removed these and
looked over the board for any shorted traces etc. - the bigger concern
remains the complete failure of COS input logic.
- Looking for any guidance from other users in the group in the
meantime.
- Perhaps any other others of the XPR8300/8400 would also share their
experiences and their pinning, we included a snapshot of our CPS Accy
settings.
Has anyone else seen this issue before? Could all three COS input
stages actually be defective, or are we missing a board-level config
step? … We did successfully connect it to the PC softwaree but did not
change any default settings, as it should have worked at least on the
?�?basic default?�? settings without changing anything correct?
?
Thanks in advance,Bryan, KB9UZO
Eastern Colorado Repeater Association-ECRA
------------------------------------------------------------------------------
President and CTO - Arcom Controllers
Makers of repeater controllers and accessories
Phone: (503) 678 6182
Authorized Dealers for Kenwood and Telewave.
We offer complete turn-key repeater packages!
"We don't just make 'em. We use 'em!"
![[]](http://www.arcomcontrollers.com/arcom.png)
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I run the RSS in a 32 bit Win XP VM using Virtual Box on my win10 64 bit laptops
Have to watch the USB com port setting to match..works great
You need to map external PTT to.the wireline audio in using the RSS.? Set it as a base and not repeater ..the external controller will work fine.? COS and PL detect out of the MTR are high going logic...ICS sells adapter boards that brings everything to a DB9 ..I'm using that on my MTR.. connects to my RLC and even provides 12V to the controller power plug
Chris WB5ITT?
There is adequate documentation on the repeater-builder website. Don't forget to save the codeplug as received (you need a 32-bit Windows OS). Some programming settings are required for the wireline audio to work, and Moto's REALLY WEIRD audio alignment
procedure.
73
-de "Curly" John NI0K
call me: 6100271
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You need to map external PTT to.the wireline audio in using the RSS.? Set it as a base and not repeater ..the external controller will work fine.? COS and PL detect out of the MTR are high going logic...ICS sells adapter boards that brings everything to a DB9 ..I'm using that on my MTR.. connects to my RLC and even provides 12V to the controller power plug
Chris WB5ITT?
There is adequate documentation on the repeater-builder website. Don't forget to save the codeplug as received (you need a 32-bit Windows OS). Some programming settings are required for the wireline audio to work, and Moto's REALLY WEIRD audio alignment
procedure.
73
-de "Curly" John NI0K
call me: 6100271
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Re: Suggestions for service monitor
Motorola R2600 series with tracking generator option.
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One and done.
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Chris/AJM
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--
Chris Baldwin, CETSr. (KF6AJM)
Trustee - MetroNET Cal. Intertie (KB3PX)
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Arcom RC210 Not Responding to COS Input on Any Port (Confirmed Good Repeaters)
Hi all, Re-posting this as for some reason our first post never made it through:?
We're running into a major issue with a recently assembled RC210 — it’s not responding to valid COS signals or PTT (besides manually triggering it) on any of the three ports, even though the connected repeaters are confirmed working.
We're interfacing with both a Motorola XPR8300 and a Kenwood TKR-740 — and here’s what we’ve confirmed:
Repeater Tests (XPR8300 & TKR-740)
- COS (Pin 21 / GPIO3 on XPR8300): Drops from ~4.66V to ~0.53V when receiving a signal (confirmed using XPR Pin 16 as GND).
- PTT (Pin 17 / GPIO1): Keys repeater successfully when pulled low.
- We repeated these tests using a Kenwood TKR-740 repeater with the same result — valid COS signals present and working as expected.
- All measurements taken directly at the repeater accessory connectors using a multimeter. RC210 was disconnected for isolation testing.
RC210 Fails to Detect COS
- All jumpers set per manual (e.g., JP2 = 1–2 for Active Low input on Port 1).
- GND is confirmed clean and consistent across DB9 pins 6, 8, and 9.
- Simulating COS by shorting DB9 Pin 7 (COS IN) to Pin 6 (GND) results in:
- No COS LED
- No PTT trigger
- No voltage drop on PTT OUT (Pin 3)
- However, manually shorting DB9 Pin 3 to GND causes the PTT LED to light and voltage to drop to 0V — confirming the RC210's PTT output circuitry is working correctly. ** All three ports, no automatic PTT detection either **
- Same behavior confirmed on Ports 1, 2, and 3 — no COS detection on any port.
We had this unit assembled by Mr. Ken at Arcom, and he sent it back to us in a timely manner, we also emailed him our findings as well, hopefully he can help us with this.
?
Additionally, during troubleshooting the board, we found several clipped component leads left between pads and vias. We removed these and looked over the board for any shorted traces etc. - the bigger concern remains the complete failure of COS input logic.
- Looking for any guidance from other users in the group in the meantime.
- Perhaps any other others of the XPR8300/8400 would also share their experiences and their pinning, we included a snapshot of our CPS Accy settings.
Has anyone else seen this issue before? Could all three COS input stages actually be defective, or are we missing a board-level config step? … We did successfully connect it to the PC software but did not change any default settings, as it should have worked at least on the ‘basic default’ settings without changing anything correct?
?
Thanks in advance,
Bryan, KB9UZO
Eastern Colorado Repeater Association-ECRA
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Suggestions for service monitor
With SDR being a thing these days, is there any software that could turn say a BladeRF into a capable service monitor for duplexer tuning and alignment? Or any off the shelf solutions which just connect to a computer with USB for operating the service monitor so you don't need the expense of a box with everything in it, similar to the USB oscilloscopes?
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If not, what is the best bang-for-your-buck ebay-able service monitor that is suitable for most basic service/alignment tasks on repeaters/mobiles/duplexers?
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Thanks,
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Mike
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Just getting into DMR with some motorola XPR stuff, looking for suggestions as to if the stuff I bought is actually a good fit for my use case
Hi,
?
I recently bought a UHF XPR 8300 repeater and a UHF XPR 5550 at a hamfest. I'm planning on using these on a commercial pair. I was hoping to use enhanced encryption for this, which I think licenses can be bought for around $50 based on a quick search. The person I bought it from didn't seem super familiar with encryption, but was saying that the repeater is not able to load an encryption key, only the mobiles/portables can. That seemed strange to me since there was also someone else there that seemed very familiar with this repeater, saying that yes you can use an analog tone remote through the back connector, but I was thinking how could the repeater encrypt the traffic which is originating directly from it if it can't load an encryption key? And now it seems like it can't do that at all. Maybe through a digital remote where you load the key into the remote itself?
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I also bought an XPR 5580 for 33cm ham use, analog to start with there but hoping some DMR 33cm repeaters come on the air near me at some point.
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I probably should not have impulse bought these, especially the repeater, since now that I'm looking into it more and I'm not sure if it fits my use case. I suppose as long as it works the price wasn't bad and I can sell it or possibly use it as a portable repeater for occasional temporary setups.
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First off, is it not possible to use analog 4 wire tone remotes into the rear connector of the XPR 8300? I was hoping to be able to have the repeater set up for DMR but still use analog tone remotes connected to it, but I don't think that is possible now.
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I was also hoping to use the ethernet interface to link it to voip infrastructure, similar to allstarlink (but for my private use), mainly phone patch and any other reason I want a computer based interface to it where the computer can TX/RX audio to/from it, for instance custom command & control purposes, and potentially a bridge to allow me to use my existing analog tone remotes in the event the repeater can't handle that itself. I think this might be possible with something like MMDVM where hopefully the repeater can handle the encryption (if it even can)??
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Originally I was just assuming that it was possible to do analog voice into it and have a TX/RX/COR/PTT line to something like an RA-42, and then have that audio digitized in the repeater. I assume if that were possible then somewhere in the repeater configuration you would tie the analog 4-wire line into a specific DMR talkgroup, but it seems it was very dumb of me to make all these assumptions.
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If the repeater was able to handle analog voice into it, hopefully it would have multiple paths like the Quantar, one could be for the RA-42 and the other could go direct to the tone remotes, with the remote F keys able to select different talk groups.
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If this was a dumb purchase for this use case then, is there a repeater which could handle some or all of these use cases?
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Thanks for reading!
Mike
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There is adequate documentation on the repeater-builder website. Don't forget to save the codeplug as received (you need a 32-bit Windows OS). Some programming settings are required for the wireline audio to work, and Moto's REALLY WEIRD audio alignment
procedure.
73
-de "Curly" John NI0K
call me: 6100271
|
Re: Kenwood NXR 810 repeater
I prefer to use the 8 pin modular cable.? That allows me to go to a site and make programming changes from the front panel of the repeater and not have to go in the back and possibly remove a db-25 that connects to something else like a controller.? The less time I spend in the back of the rack, the less time I have to accidentally disconnect something else.
Joe, K1ike
toggle quoted message
Show quoted text
On 4/4/2025 7:09 PM, Ken Arck AH6LE via groups.io wrote: That would work too but the only time that connection is absolutely necessary is when uploading firmware to the repeater (same as the TKRs). Otherwise, the DB25 on the back panel is fine (straight through, non null modem connection)
Ken
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Re: Attempting to program a Maxon SM2150. Looking for proper prog cable. Have software.
Yes Tim. The cables seem to have gone the way of the dodo!?
Good luck.
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Thanks. I did finally figure that out. The guy we got this from had the wires stuffed into the square holes. I moved them to the round holes.
I'm getting about 1.6vpp on the rx audio lines, that seems like plenty of audio. The cable from the mtr2k to a 9pin for the controller rings out properly, I'm seeing the 1.6vpp at the 9pin end.
It's gotta be something in the controller.? That's for tomorrow.?
Couple items to look at...
Wireline card present in the top slot of the cage?
Tuner menu Wireline TX audio level turned up (often found Zeroed out)?
Set to Full Duplex?
The black connector does not come off. You use a very small sturdy pin in the round hole above each wire slot that will release the clamp. I use a fairly large diode lead to pop mine open.?
I'm trying to figure out why our mtr2000 isn't passing any audio. We're using an external repeater controller through the wireline connector. This is new to us, and we're trying to get things set up before we go to the site.
Before I try too hard and break something...
Is that 4 pin connector (J6) supposed to come off?
How do I release the wires? I tried pushing into one of the small holes, figuring that would release a clamp. The wires aren't budging.
Thanks. Don
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Couple items to look at...
Wireline card present in the top slot of the cage?
Tuner menu Wireline TX audio level turned up (often found Zeroed out)?
Set to Full Duplex?
The black connector does not come off. You use a very small sturdy pin in the round hole above each wire slot that will release the clamp. I use a fairly large diode lead to pop mine open.?
I'm trying to figure out why our mtr2000 isn't passing any audio. We're using an external repeater controller through the wireline connector. This is new to us, and we're trying to get things set up before we go to the site.
Before I try too hard and break something...
Is that 4 pin connector (J6) supposed to come off?
How do I release the wires? I tried pushing into one of the small holes, figuring that would release a clamp. The wires aren't budging.
Thanks. Don
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Re: 220Mhz ACSB amplifier
Chris,
What are you referring to?
WZ5TX
David “Tyler” Bufkin
toggle quoted message
Show quoted text
You guys are making me sick here. I haven't heard of people in 6 m down here in Southeast Texas and it's one of my favorite bands!?
Chris WB5ITT?
6M has been open MANY times over the past month or 2 to Oregon. And since we're at the peak of the cycle, this summer should be great!
South America, the Caribbean, South Pacific. Tons of DX
Ken
At 12:46 PM 4/5/2025, you wrote:
Interesting subject and? Mike will 6M open to Oregon this year?
I evaluated a Linear Modulation Tech PA, w/ 24Vdc it took a +8dBm input to deliver 100W CW.
I considered using one for my ACSB repeater (yeah, really!)
I built a 2 channel combiner for it (pic attached). I combined 2 systems successfully, the short cavities are special design for a bit broader tuning for ACSB (thanks Wacom!)
I was testing them into a commercial 200W PA made for a military application (all mode) then I accidentally switched it open circuit for a few millisecs (long story) and it went into oscillation and blew a transistor so the project was put on hold.
I intend to repair it or replace it with an ESP1100 PA.?
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I believe James KB0HNX is using a Securicor PA for their 220 FM rptr in Nixa MO. He frequents the forum and might add how they are cooling it.
Reid? W6MTF
------------------------------------------------------------------------------
President and CTO - Arcom Controllers
Makers of repeater controllers and accessories
Phone: (503) 678 6182
Authorized Dealers for Kenwood and Telewave.
We offer complete turn-key repeater packages!
"We don't just make 'em. We use 'em!"
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In California it's Cactus, in Texas it's Armadillo... You know what I'm talking about?
Jim Reese WD5IYT, sk, had an error message in the Dillo controller that if you entered an unknown command it would spit out FU in CW... When I asked Jim about it, he said "oh that stands for function unavailable!! "
I have since replaced the error messages in my Linkcomm controllers with that ??
Chris WB5ITT?
ugh...that's as bad as the guy that used to use phonetics...he got
banned from just about every repeater and club in nearly 100 miles...I'm
sure he got in trouble with 'the man' too...interfering with emergency
nets in progress was a big one too.
On 4/5/2025 7:20 PM, Nate Bargmann via wrote:
> * On 2025 05 Apr 17:48 -0500, Jim Barbour via wrote:
>> Sorry, I'm not getting it...
>>
>> BMEK(unknown)DL
>>
>> Huh?
>
> Work out the letters right to left.? Hint:? The Morse characters are
> sent in reverse (the clue for me was '.-.-').
>
> 73, Nate
>
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Chris Baldwin
Rob VK5TRM
Chris Boone WB5ITT
Ken Arck AH6LE
wheelz
maxwelloau