CDM1250 + Midian UD-1B DMH

[jchabalie]

I appologize if this is a little lengthly, but I'm hoping that someone can find or has an answer for me. One the fire departments in my township has a CDM1250 hooked up to a Midian UD-1B DMH tone decoder. From the best I can gather is that the decoder decodes the pager tones when received from the dispatch center and then re-broadcasts them from the CDM1250 to activate their pagers a second time. The problem is, after re-programming the radio, the tones are not being rebroadcasted the second time and the tones are not able to be manually activated from the station. Instead, It broadcasts an open carrier squelch followed by the radio identifier being transmitted. The only thing I am assuming is that the accessory pins are not programmed correctly after the new codeplug was programmed into it since everything worked ok prior to that. I've never come across a set up like this before so I'm about out of thoughts. If anyone has any ideas or thoughts please let me know. Thanks!

[SteveC0625]

You are probably correct in your assumption. I have a GM300 hooked up to a Zetron Model 19 Simplexor that basically does the same as your Midian.

I was lucky enough to find the original installer's notes on the setup so I know what each line into the GM300 is used for. Ultimately, I was able to get the code plug read so that I could affirm which accessory pin is programmed for each wire.

Do you have the original code plug? If you do, just see what the pins are set for.

Any chance you can find the installer's notes for the Midian, or the manual?

FWIW, I am replacing the GM300 with a CDM1250 in the next couple of weeks and will be moving the Zetron over as well.

[SteveC0625]

Additional: Here is a link to the manual for the Midian unit. http://www.midians.com/html/..%2Fmanual ... -07-11.pdf

If you can trace each wire to the 20 pin accessory connector on the CDM, you can determine how each pin needs to be programmed.

Also, if you have the original code plug, you may want to verify that all the call and signalling systems are correctly programmed and that the personality has the right signalling system designated.

[Jim202]

I appologize if this is a little lengthly, but I'm hoping that someone can find or has an answer for me. One the fire departments in my township has a CDM1250 hooked up to a Midian UD-1B DMH tone decoder. From the best I can gather is that the decoder decodes the pager tones when received from the dispatch center and then re-broadcasts them from the CDM1250 to activate their pagers a second time. The problem is, after re-programming the radio, the tones are not being rebroadcasted the second time and the tones are not able to be manually activated from the station. Instead, It broadcasts an open carrier squelch followed by the radio identifier being transmitted. The only thing I am assuming is that the accessory pins are not programmed correctly after the new codeplug was programmed into it since everything worked ok prior to that. I've never come across a set up like this before so I'm about out of thoughts. If anyone has any ideas or thoughts please let me know. Thanks!

You didn't indicate if the CDM even keys up to rebroadcast the tones. If it does key up, then I guess you have no TX audio.

There is a gain setting in the radio software for the external mic input. If the radio is keying, then my guess is that you need to jack up the external mic gain settings and not run it in the default AGC setting.

If your not even keying the radio, then the external PTT pin selection is not done in the radio software.

Jim

[jchabalie]

It seems that the radio does key up, but it's just dead air followed by the MDC being transmitted. I unfortunately do not have the original CP or installer notes. I've tried changing some of the accessory pin settings but still can't get the tones to transmit.

[Jim202]

It seems that the radio does key up, but it's just dead air followed by the MDC being transmitted. I unfortunately do not have the original CP or installer notes. I've tried changing some of the accessory pin settings but still can't get the tones to transmit.

If you go into the radio software, double click on the "Radio Configuration" line. Then go to the "Accessory Configuration" tab selection. Down on the lower right side you will see a selection that says "EXT PTT Audio Source". Make sure it is set to "EXT MIC AUDIO".

Your TX audio from the encoder should be wired to pin 2 on the accessory connector.

Can't help you on the PTT pin as that can be set to several pins in the software. You will just have to look to see which pin your wired to and then make sure that pin is set in the software for the external PTT input. That is found in the "Accessory Pins" tab.

Jim