Trouble with CDM1250 repeater

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radio_rob_nj
Posts: 54
Joined: Wed May 11, 2005 12:28 am
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Trouble with CDM1250 repeater

Post by radio_rob_nj »

I've been running two Maxtrac's back to back with a Chinese, one way with delay, repeater cable for a few years and it works well, but I wanted to upgrade. I have two CDM1250's that I thought I'd swap out. I programmed them the same but....nothing. I'm hoping I've just missed a setting somewhere. Here's where I'm at troubleshooting-wise:

When both Maxtrac's are connected, it works.
When the Maxtrac is used for RX and the CDM is used for TX, it works.
When the CDM is used for RX and the Maxtrac is used for TX, the Maxtrac does not key up.
When both CDM's are connected, the TX CDM radio does not key up.

It seems the RX CDM is giving me the issue. I'll post pictures which I believe are relevant. If you need more, let me know. Also I'll try any troubleshooting steps you recommend.

Below are pictures of the repeater cable and the setting in CPS.

In order, the description of the pictures is as follows:

Bottom of repeater cable, Top of repeater cable, RX CDM Pin configuration, RX CDM Accessory configuration, TX CDM Pin configuration, TX CDM Accessory configuration.

https://photos.app.goo.gl/RpLvbtUlrunhFbOm1

Thank you for any help!
I'll see your 4.1 and raise you a 7.13
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Bill_G
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Re: Trouble with CDM1250 repeater

Post by Bill_G »

Try active low on the rx radio PL/CSQ detect line.
radio_rob_nj
Posts: 54
Joined: Wed May 11, 2005 12:28 am
What radios do you own?: Motorola, ICOM, Harris, Tait

Re: Trouble with CDM1250 repeater

Post by radio_rob_nj »

Thank you for the suggestion.

No dice, still doesn't key up the TX radio. I wasn't totally sure if it was pin 4 or 8, so I did both.

I even thought it could be a problem with the radio so I swapped the RX and TX radios, but that didn't solve the problem, either.

If only I had a Quantar or MTR in the right range.....

Any other suggestions?
I'll see your 4.1 and raise you a 7.13
radio_rob_nj
Posts: 54
Joined: Wed May 11, 2005 12:28 am
What radios do you own?: Motorola, ICOM, Harris, Tait

Re: Trouble with CDM1250 repeater

Post by radio_rob_nj »

When I use the Maxtrac as the RX radio: If the radio has power but is not switched on, the light on the repeater board illuminates just as it would if there is a transmission. When I remove the power cable, the light goes off. It seems like there is a pin that is powered under certain conditions in the Maxtrac, but is not so in the CDM.
I'll see your 4.1 and raise you a 7.13
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Bill_G
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Re: Trouble with CDM1250 repeater

Post by Bill_G »

Read the Maxtrac to see how it's accy port is set up.
radio_rob_nj
Posts: 54
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What radios do you own?: Motorola, ICOM, Harris, Tait

Re: Trouble with CDM1250 repeater

Post by radio_rob_nj »

I did. I set the CDM up exactly the same way. The only difference was in the Maxtrac, pin 3 was not in the list of pins to change, and it is on the CDM. I think that is supposed to be EXTERNAL MIC PTT on the TX radio, and it is set that way (It's an input only pin).
I'll see your 4.1 and raise you a 7.13
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Bill_G
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Re: Trouble with CDM1250 repeater

Post by Bill_G »

Are you certain you centered the accy plug in the CDM connector correctly?

Image

Image
radio_rob_nj
Posts: 54
Joined: Wed May 11, 2005 12:28 am
What radios do you own?: Motorola, ICOM, Harris, Tait

Re: Trouble with CDM1250 repeater

Post by radio_rob_nj »

Bill_G,

Yes, the plug is in the correct orientation and is in the middle of the CDM accessory port. When it is plugged in, there are two pins on either side which are not plugged in.
I'll see your 4.1 and raise you a 7.13
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Bill_G
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Re: Trouble with CDM1250 repeater

Post by Bill_G »

Had to check.

Well, it sounds like voltmeter time. You have to verify that (A) the tx CDM will xmit when a ground is applied to pin 3, and (B) that a high on the rx radio pin 8 turns into a low on tx pin 3.
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gatekeep
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Re: Trouble with CDM1250 repeater

Post by gatekeep »

From experience some of the Chinese cables that have a timing delay that use latent +12v on pin 10.

I've noted that some MaxTracs and GM300s I have will have +12v on pin 10 when turned on. CDMs don't have this and pin 10 is always low.

It is a long shot of course, because those Chinese cables are a dime a dozen. Check the cable with the active adjustments, for a voltage regulator connected to pin 10.
- Bryan
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wavetar
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Re: Trouble with CDM1250 repeater

Post by wavetar »

Gatekeep may very well be right, since a delay circuit would require power from somewhere. If so, jumpering pins 10 & 13 in the Chinese RX cable end *should* fix it, as that's where the switched V+ is in the CDM. It is also Pin 13 in Maxtracs, but they may have gone with the first pin they found voltage on in the Maxtrac. There is no visible trace on pin 13 in your pictures, whereas pin 10 is definitely going to a transistor.
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