CDM 1250 Lowband, low TX audio above 50mhz

The General forum is where users can discuss any topic regarding Motorola communications equipment - hardware, software, etc. There are also several focused forums on this board, so please take the time to ensure that your questions doesn't fall into one of those categories before posting here!

Moderator: Queue Moderator

Post Reply
Beekeeper
Posts: 7
Joined: Tue Aug 15, 2006 6:43 pm

CDM 1250 Lowband, low TX audio above 50mhz

Post by Beekeeper »

I have noticed a problem with low band CDM1250 radios when you transmit above 50.100 mhz, it's about half of what the deviation below 50.1 mhz. At 49.400 mhz the TX audio is about 5.2 khz on a monitor but falls to about 2.9 khz in the ham bands. Any ideas? I have this issue on all 5 of the radios I have. Thanks!
Jim202
Posts: 3610
Joined: Sun Sep 09, 2001 4:00 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by Jim202 »

Beekeeper wrote:I have noticed a problem with low band CDM1250 radios when you transmit above 50.100 mhz, it's about half of what the deviation below 50.1 mhz. At 49.400 mhz the TX audio is about 5.2 khz on a monitor but falls to about 2.9 khz in the ham bands. Any ideas? I have this issue on all 5 of the radios I have. Thanks!


The first question I would ask is what band width setting were the programmed channels set to? It's been a while since I played with the low band versions. Most of the time I work on VHF and UHF versions. So I could be wrong on the option even being there.

Jim
Beekeeper
Posts: 7
Joined: Tue Aug 15, 2006 6:43 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by Beekeeper »

All settings are the same for all ch's, 20khz. It makes no difference on the 25/30khz setting either.
User avatar
escomm
Queue Moderator
Posts: 5170
Joined: Fri Mar 24, 2006 8:24 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by escomm »

Seems the radio is going out of band. As the tuning points are all in band it stands to reason this may be a tuning issue first and foremost. The radio is only referencing softpots within its operating range.
Will
Posts: 6823
Joined: Tue Sep 04, 2001 4:00 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by Will »

escomm wrote:Seems the radio is going out of band. As the tuning points are all in band it stands to reason this may be a tuning issue first and foremost. The radio is only referencing softpots within its operating range.
Exactly, that is what I have found too.
Beekeeper
Posts: 7
Joined: Tue Aug 15, 2006 6:43 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by Beekeeper »

VCO ATTN. @ 20 khc fixed it.
User avatar
phrawg
Posts: 690
Joined: Sun Sep 09, 2001 4:00 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by phrawg »

Hi Beekeper. I was just reading some posts here and saw this one. I have a CDM1250 42-50 Mhz split
that I would like to put on 6 Meter ham. How did you program it up into the 50-54 range.
Must be a "variant" version of CPS ? Interested in more info if you can share it on how this works.
Dick, N5SPU Aka Phrawg
BBbzzzzz... ZAP.. GULP !!! ahhhh GOOD fly !
User avatar
SD70MAC
Posts: 408
Joined: Mon Sep 10, 2001 4:00 pm

Re: CDM 1250 Lowband, low TX audio above 50mhz

Post by SD70MAC »

phrawg wrote:Hi Beekeper. I was just reading some posts here and saw this one. I have a CDM1250 42-50 Mhz split
that I would like to put on 6 Meter ham. How did you program it up into the 50-54 range.
Must be a "variant" version of CPS ? Interested in more info if you can share it on how this works.
Dick, N5SPU Aka Phrawg
Phrawg,

Here is how I done my 42-50;

https://www.p25.ca/threads/1126-Profess ... -band-hack

I had 2 CDM1250 42-50 and one of them did not work OOB to 54 no RX or TX. I do OOB with my CDM1550LS+ 450-520 and it works like a champ !
SD70MAC out

My collection;
XTS5000 VHF FPP,XTS3000 VHF M1&M3,XTVA,XTS2500 UHF Q FPP,Astro Spectra"s W3 VHF,W9 VHF,W7 800,HT1250 35-50,XPR4500 Q,2 CDM1550LS+ VHF 160ch,CDM1550 X 160ch VHF 25w,MAXTRAC 42-50 32ch,CDM1250 42-54
Post Reply

Return to “General Motorola Solutions & Legacy Radio Discussion”