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CDM 1250 Lowband, low TX audio above 50mhz
Posted: Sun Feb 23, 2014 6:14 pm
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!
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Mon Feb 24, 2014 4:36 am
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
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Mon Feb 24, 2014 4:51 am
by Beekeeper
All settings are the same for all ch's, 20khz. It makes no difference on the 25/30khz setting either.
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Mon Feb 24, 2014 7:07 am
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.
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Mon Feb 24, 2014 12:05 pm
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.
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Tue Feb 25, 2014 4:15 am
by Beekeeper
VCO ATTN. @ 20 khc fixed it.
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Thu Mar 06, 2014 11:59 am
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
Re: CDM 1250 Lowband, low TX audio above 50mhz
Posted: Sat Mar 08, 2014 1:53 pm
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 !