MMDVM with Motorola CDM1250s

zacabo

Member
Joined
Aug 22, 2010
Messages
74
Location
FL
I'm currently trying make a portable repeater using Scott Zimmermans board from repeater builder and two Motorola CDM1250s. I don't want to link or use it as a hotspot just standalone. I primarily want to use DMR and P25. I have both modes enabled and they are green on the dashboard. It appears the DMR beacon is being transmitted. But when I try to key up using a Motorola XPR 6550 I get the talk inhibit tone. I have heard I may need to pot on the output audio from the RX radio. Not sure if there is something I'm missing or not. Just hoping someone else may know or have a suggestion for me. Thanks
 

2IR473

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Premium Subscriber
Joined
Aug 22, 2004
Messages
57
I just built two repeaters using the Zimmerman STM-32 board. I found it best to connect to an active DMR talkgroup so I could have traffic putting the repeater in transmit, and then turning the TX pot until the audio was being received on my DMR HT.
 

ergbert

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Joined
Feb 6, 2018
Messages
79
Location
FN22
I'm in the process of doing the same, but with a CDM750. Trying to test it in simplex hotspot configuration while waiting for my other CDM to arrive, and I'm running into some oddness. I'm not familiar with Mother M's products really, I'm a bit of a Tait radio fan. I am getting audio out of the CDM's internal speaker when transmitting or receiving. My previous simplex hotspot radio was a Tait TM8105, which is a data-only transceiver... is the fix as simple as unplugging the internal speaker on the CDM or am I overlooking something in the software setup?

The hardware config is a UHF 403-470 CDM750, connected to a Repeater-Builders STM32DVM pihat via a Repeater-Builders cable.
 

zacabo

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Joined
Aug 22, 2010
Messages
74
Location
FL
I'm trying a similar setup but with a CDM1250. I still haven't figured it out yet.
 

zacabo

Member
Joined
Aug 22, 2010
Messages
74
Location
FL
I don't have a ham license so i can't connect and see if I can hear digital talkgroups. I have a business license just want a standalone DMR/P25 repeater
 

wa8pyr

Technischer Guru
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Joined
Sep 22, 2002
Messages
5,144
Location
Ohio
Are your radios programmed for flat audio? Setting the radio for flat audio would be recommended, or the filtering could mess up digital audio and hamper the ability to receive it. The Maxtrac/Radius series (CDM predecessors) have an internal jumper which must be configured for flat audio; I don't recall offhand but I'm pretty sure the CDM series use a software switch in CPS to set either flat or filtered audio.
 

a417

!#
Joined
Mar 14, 2004
Messages
1,672
I don't recall offhand but I'm pretty sure the CDM series use a software switch in CPS to set either flat or filtered audio.
Correct, under the Acecssory Pin configuration tab you can change Flat/Filtered Audio output along with some pin duties in the CPS.
 
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