[arm-allstar] Programming Motorola CDM1250 for Use with Maxtrac Adapter?

[Larry Mollica]

Chris, see comments below in line. Hope this is helpful.  
Larry AD6G

On Jan 23, 2022, at 9:40 AM, Chris via ARM-allstar arm-allstar-at-hamvoip.org wrote:

> 
> I’m blind, and the Motorola programming software is not accessible to my
> Windows screenreader. So, I will have to ask him, or someone else, to
> program it for use with my Maxtrac and Pi running Hamvoip.
> 

FYI The programing software is definitely more complicated than the usual ham radio programing software. Took me a little while to figure out.
Your best bet would be to find someone local who can program it.

> 
> Questions:
> 
> Can these be set to lower power? If so, which power level should I choose?

The power range on the CDM model (AAM25RKD9AA2AN) is 25-40 watts, per the service manual. I’ve seen the 45 watt figure being kicked around before, not sure what the deal is with that. You can program different power levels per channel, but you are limited to your choice of two levels you define. 

CDM line of low power radios range is 1-25 watts per the data sheet. It has been my experience that low power models are harder to come by.



> i.e. I want to generate the least amount of heat. Yes, I have a
> temperature-controlled fan ready to go on top of the radio. Some radios seem
> to generate more heat on their lowest power setting.
> 

These radios can get quite warm, including the low power radios. A fan is a must if used for repeater or other situations where they will have a lot of transmit duty. We were running a high power radio at 25 watts for a while with no fan and it got blistering hot, lesson learned. I’ve been told to run them at lowest power but I don’t have any definitive data as to if that is making more heat or what.


> 
> 
> Besides putting in my frequency (446.140 simplex), what other things does he
> need to program so things work with the Maxtrac and Hamvoip? This needs to
> be plug-and-play.


Interface leads for PTT, COS, CTCSS do not come out on fixed pins. They must be programed to whatever pin is to be used. If you are buying a pre made interface cable, you’ll of course need to go by those for the pin numbers.

There are fixed pins for RX out, EXT_MIC_AUDIO (pre-emphasis & limiting in the radio), and FLAT_TX_AUDIO (pre-emphasis & limiting must be done external to radio, intended for data use). We’ve been using the EXT_MIC_AUDIO connection.

Receive de-emphasis on/off is software programed. 

My memory is a little fuzzy on this point, but some combination of “ptt” settings related to data and/or flat TX audio results in no xmit PL tone being sent. If you avoid all the data/flat_TX stuff, this is not a problem. I believe there may be some setting combination that will give you flat tx audio with PL. I don’t use that because while you can do pre-emphasis in the node, AFAIK there is no limiting feature in the node and the flat input bypasses the radio’s limiter.

FWIW I have run into problems with two different CDM radios, one UHF one VHF, wherein noticeable harmonics of the receive PL tone are heard in the RX audio. I “fixed” one of these by implementing audio notch filters in rpt.conf. Definitely a band-aid but it actually works fairly well.

Ran into a problem with one radio, the xmit pre-emphasis curve was not curvy enough, had rather muddy xmit audio. “Fixed” by inserting a capacitor in series with the TX audio lead, experimentally finding a value that made it sound better. Yep, another band-aid.


http://www.repeater-builder.com/
is a great source of information on these and other Motorola radios.



> 
> 
> 
> The noe is in a basement, below ground, and will be connected to a ¼ wave
> wire j pole, and I do not typically get any intermod on 70 CM. Do I really
> need to set a PL tone? I’d prefer full audio bandwidth, i.e. not engaging
> Hamvoip’s audio filtering if possible.
> 

I personally would not operate a node that might at some time be connected to a hub system without receive PL or DPL. IMHO Carrier squelch is a recipe for getting blacklisted. Transmit PL is a different story. I use it, but I can’t see where not having TX PL could cause a problem for anyone else, that I know of.