CM200 RF Power Issues

[NE2WAY]

Has anyone else experienced issues with the RF Power on the CM200's

We have 20 CM200's we took in trade. The radios are just over 2-years old and are 45-Watt VHF
Everyone of the radios puts out different power ranging from 5-watts - 19-watts none of them are close to 45

We also have a customer who's fleet has a bunch of 45-watt VHF CM200's and same thing wattage is all over the place none of them come close to the specification.

I have tried a number of watt meters to rule out a bad meter.

anyone have any ideas?

[Bill_G]

They are used. They could be worn out, and needing some TLC. Have you bench tested them, and attempted alignment?

[NE2WAY]

We have not benched tested yet. Just found it odd that, that many would be so far out of spec

[Al]

I've seen an occurrence where a CM300 sat powered up for many months in receive mode and when bench tested for low tx output power the power came back to 45 W spec while the tx was keyed for extended time and the PA/heatsink got quite warm with no adjustments being done. It then stayed at 45 W, couldn't make it fail again. And it performs at spec to this day. I did notice that while the tx power was 8-16 watts at the initial inspection it was erratic until it finally returned to normal after extended keydown. The unit that I noticed this behavior on was also about two years old.

[guy being a guy]

You mentiom you have 20 and another guy has a bunch .............Quite a few lets say .
ALL of them are low TX power with levels all over the place .
The common denominator is the watt meter you are using - you tried another with the same sporadic results .
You did not mention the RF cable your using to test them. Also are they in or out of the vehicle - your power supply to the radio can do this as well so don't overlook that . If you have them on a bench and using your own power supply than check them in ONE vehicle with a good charged battery in the vehicle.
Use another high quality RF cable and of a different length than your current one.
The cable itself may be tits up, poor connectors on either end or a length that the VHF freq's dont like.
Also are the freq's within the bandwidth that the radio is made for ,or has it been taken out of band and not ever aligned correctly ?
This model is pretty durable and I find it almost impossible that 30 or so radios all have low TX power.
Bench testing I bet will be fine and its the RF cable your using or some other tampering that will become clear once all the pieces of the puzzle come together.

[Bill_G]

You mentiom you have 20 and another guy has a bunch .............Quite a few lets say .
ALL of them are low TX power with levels all over the place .
The common denominator is the watt meter you are using - you tried another with the same sporadic results .
You did not mention the RF cable your using to test them. Also are they in or out of the vehicle - your power supply to the radio can do this as well so don't overlook that . If you have them on a bench and using your own power supply than check them in ONE vehicle with a good charged battery in the vehicle.
Use another high quality RF cable and of a different length than your current one.
The cable itself may be tits up, poor connectors on either end or a length that the VHF freq's dont like.
Also are the freq's within the bandwidth that the radio is made for ,or has it been taken out of band and not ever aligned correctly ?
This model is pretty durable and I find it almost impossible that 30 or so radios all have low TX power.
Bench testing I bet will be fine and its the RF cable your using or some other tampering that will become clear once all the pieces of the puzzle come together.

+1

I can definitely get behind this. Been there, done that, got the tee shirt, and a flat spot on my forehead from banging my head on the wall. I've had test cables and/or adapters with intermittent open center conductors. I've had wattmeters with flakey fwd/rev det contacts. I've had flakey power cables, flakey fuse holders, flakey grounds, flakey center pins on NMO mounts, and flakey ant conns on radios. And if you mix them all together on the job, you get a bunch of radios that look terrible. You chase you tail for a bit until you get methodical about working the problem.

[anniegirl]

I have had 10 units come in out of 100 I had on my bench and some never got off 10 watts. Before you think the PA is bad make sure you check the power setting that is right in the programming software. So many blow right past this. The radios low power and high power can be adjusted. I purchased some with supposedly low power issues and here all it was is that someone had programmed the high power down to 10 watts. Then I did have some with low power and I got these up from 10 watts up to 50 in a high power unit by simply disassembling the radio (2 min job), remove the board, flip it over and clean off the PA heat sink pads and re-applied new lithium. All the low power units I had jumped up to full power. I think users run them at full power and the heat sinks get hot and score the grease making them lose contact and the thermal protection shuts down the power. To me its worth a couple minutes and a little white lithe.

[NE2WAY]

Thanks the post is over 3 years old, however that is very useful information

We just did PM checks on a fleet of 100 and about 10 of them have the low power issue. I will try and see if the procedure you outlined gets them back to life.

[anniegirl]

Very good, let me know how it works our. Always nice to help someone

[Wiregeek]

I'm on my first cup of coffee here, but my brain just saw this and told me that computer heatsink grease (Arctic Silver) might be an improvement over plain white lith for this application. If it is, it's gonna be an unnoticeable improvement in performance, but should provide a higher resistance to damage-over-time.