CDM Alarm system

[Radio_Shop]

Hello gents.

I have a question for you I set up station alarm packages in multiple fire and ambulance stations using either a cdm 1550 or 1250. I do this by obviously programming the a/b tone format in the quick call II part of the cps. I then use pin 4 on the back of the radio to trigger a relay, this relay is powered off the same inverter the radio is being powered from.

Now here is the problem, sometimes pin 4 triggers the relay like its suppose to and other times pin 4 does nothing when the radio gets tones. Ive tested it by simply holding my power probe to the bare pin itself.

Now I am aware of the tab under the cps titled accsessory pins. and i have the drop down box selected to external alarm for pin #4.

Now here is my theory and it may or may not have anything to do with the problem. sometimes i ground the relay usiung the ground off the inverter, and other times I have used pin 7 on the radio plug. Do you guys thing that the relay needs to get its ground from the radio in order to have pin 4 trigger?

your thoughts?

 

[SteveC0625]

Hello gents.

I have a question for you I set up station alarm packages in multiple fire and ambulance stations using either a cdm 1550 or 1250. I do this by obviously programming the a/b tone format in the quick call II part of the cps. I then use pin 4 on the back of the radio to trigger a relay, this relay is powered off the same inverter the radio is being powered from.

Now here is the problem, sometimes pin 4 triggers the relay like its suppose to and other times pin 4 does nothing when the radio gets tones. Ive tested it by simply holding my power probe to the bare pin itself.

Now I am aware of the tab under the cps titled accsessory pins. and i have the drop down box selected to external alarm for pin #4.

Now here is my theory and it may or may not have anything to do with the problem. sometimes i ground the relay usiung the ground off the inverter, and other times I have used pin 7 on the radio plug. Do you guys thing that the relay needs to get its ground from the radio in order to have pin 4 trigger?

your thoughts?

Your suspicion is correct, I think. We have a similar setup on our CDM1250 base radio. We use the QC-II to set the alarm pin. That triggers a relay which activates a Zetron store and forward recorder. When it's finished recording, the Zetron then triggers our home receiver tones and replays the voice message via a PTT relay.

Looking at the schematics, all ground is referenced to the radio's ground.

 

[Radio_Shop]

Intersting setup you have there. My system is just used to set off multiple led lights in each crew members room then the speaker is driven off the normal 1-16 pins. Next one I build I will make sure the ground comes off pin 7 instead of the inverter and let you know how it works.

 

[SteveC0625]

Intersting setup you have there.

It's actually a back up system. Our dispatch is normally via a repeater located here in town that the county 911 can reach easily. (We have geographic challenges here at the north end of our area.) If the repeater fails, dispatch can switch to simplex off a tower far to the south. It won't hit our pagers, but it hits our base station radio just fine. A different set of tones is used for the back up alert. That triggers the Zetron. In turn, the Zetron sends out our normal pager tones plus the recorded voice message. Our radio shop put this together for us many years ago when the base radio was a GM300. We bought the CDM1250 a couple of years ago in preparation for narrowband. The shop had to come back and make a minor change to the circuitry between the Zetron and the radio. But it works just fine.

 

[pete7919]

It's actually a back up system. Our dispatch is normally via a repeater located here in town that the county 911 can reach easily. (We have geographic challenges here at the north end of our area.) If the repeater fails, dispatch can switch to simplex off a tower far to the south. It won't hit our pagers, but it hits our base station radio just fine. A different set of tones is used for the back up alert. That triggers the Zetron. In turn, the Zetron sends out our normal pager tones plus the recorded voice message. Our radio shop put this together for us many years ago when the base radio was a GM300. We bought the CDM1250 a couple of years ago in preparation for narrowband. The shop had to come back and make a minor change to the circuitry between the Zetron and the radio. But it works just fine.

That's a cool setup. I tried to do some research and it looks like the Zetron 19 is discontinued. Is that what you use or is there a newer model?

Midian has a PR-10 which looks to be similar. Anyone have experience with that one?

Thanks.

 

[pete7919]

It's actually a back up system. Our dispatch is normally via a repeater located here in town that the county 911 can reach easily. (We have geographic challenges here at the north end of our area.) If the repeater fails, dispatch can switch to simplex off a tower far to the south. It won't hit our pagers, but it hits our base station radio just fine. A different set of tones is used for the back up alert. That triggers the Zetron. In turn, the Zetron sends out our normal pager tones plus the recorded voice message. Our radio shop put this together for us many years ago when the base radio was a GM300. We bought the CDM1250 a couple of years ago in preparation for narrowband. The shop had to come back and make a minor change to the circuitry between the Zetron and the radio. But it works just fine.

That's a cool setup. I tried to do some research and it looks like the Zetron 19 is discontinued. Is that what you use or is there a newer model?

Midian has a PR-10 which looks to be similar. Anyone have experience with that one?

Thanks.

 

[SteveC0625]

That's a cool setup. I tried to do some research and it looks like the Zetron 19 is discontinued. Is that what you use or is there a newer model?

The GM300 and the encoder/Zetron 19 system were purchased in 1993. Still going strong today.

Best bet is to try to find a gently used one. The one we have seems bulletproof.

 

[Radio_Shop]

It's actually a back up system. Our dispatch is normally via a repeater located here in town that the county 911 can reach easily. (We have geographic challenges here at the north end of our area.) If the repeater fails, dispatch can switch to simplex off a tower far to the south. It won't hit our pagers, but it hits our base station radio just fine. A different set of tones is used for the back up alert. That triggers the Zetron. In turn, the Zetron sends out our normal pager tones plus the recorded voice message. Our radio shop put this together for us many years ago when the base radio was a GM300. We bought the CDM1250 a couple of years ago in preparation for narrowband. The shop had to come back and make a minor change to the circuitry between the Zetron and the radio. But it works just fine.

Very clever good thinking on their part always have to have a plan b .......and sometimes c d e f