RM Amplifier

[tchr01]

Hopefully you can tune your radio how you like. I just dont know how “tuneable” those very late Unidens are.

I'm definitely getting a hang of the ALC adjustment. It's very subtle. I do consistently get 10 to 12 PEP but average about five to eight. Are those 10 to 12 occasional peaks really going to fry my amp? I know the specs are no good that RM puts out as in their really inflated, but I would say keeping it under 15 pep would be safe right?

 

[Holydvr]

I believe you should be fine. I know I went a bit overboard on turning down the power. I can never really feel any heat from the thing, even when rag chewing on AM. I have thought about bumping things up a bit, but I will likely just leave it alone. The setup has done very well for me for what it is.

 

[tchr01]

I believe you should be fine. I know I went a bit overboard on turning down the power. I can never really feel any heat from the thing, even when rag chewing on AM. I have thought about bumping things up a bit, but I will likely just leave it alone. The setup has done very well for me for what it is.

Yes see this is my thought too. Thanks for the tips! Will report what I get in/out on my end.

 

[tchr01]

Ok so just hooked up my Bearcat 980SSB to the KL203-P.

AM: 1.25W DK / 4W PEP
SSB: 5-8W AVG / 10-12 PEP
Mic Gain : 2 (1-4 setting)
-- amp on --
AM: 15W DK / 85W PEP
SSB: 55-65W AVG / 125-130 PEP
Mic Gain : 2

Amp is just barley warm like a nice warmed up radio. Not hot at all after putting lots of auuuudiiooos on AM and SSB. Measured using a 100W dummy load and RadioShack PEP meter.

Im going to try and get some signal reports tonight. The only thing left I could think of is maybe the ratio of DK:Mod on AM may be a bit out of the 1:4 sweet spot. I do like that I have room to boost the mic gain to a 1-2 if I wanted as well (3 is pushing it hard). But I think driving this thing any more than this would be totally unnecessary for my needs. Also i'm gonna drop an old ATX 12v computer fan on top!

Thanks everyone for the comments and tips!

 

[9C1Driver]

That is about perfect right there, what a great combo.

 

[tchr01]

Ok so just hooked up my Bearcat 980SSB to the KL203-P.

AM: 1.25W DK / 4W PEP
SSB: 5-8W AVG / 10-12 PEP
Mic Gain : 2 (1-4 setting)
-- amp on --
AM: 15W DK / 85W PEP
SSB: 55-65W AVG / 125-130 PEP
Mic Gain : 2

Amp is just barley warm like a nice warmed up radio. Not hot at all after putting lots of auuuudiiooos on AM and SSB. Measured using a 100W dummy load and RadioShack PEP meter.

Im going to try and get some signal reports tonight. The only thing left I could think of is maybe the ratio of DK:Mod on AM may be a bit out of the 1:4 sweet spot. I do like that I have room to boost the mic gain to a 1-2 if I wanted as well (3 is pushing it hard). But I think driving this thing any more than this would be totally unnecessary for my needs. Also i'm gonna drop an old ATX 12v computer fan on top!

Thanks everyone for the comments and tips!

Just a quick followup after having it running for a few days. I had to boost the mic gain for locals, and needed to turn the DK from 1.2-1.5 to get enough carrier to test for SWR on the RadioShack meter. It pushes SSB average to 75-80 / 150 pep but that's still within acceptable limits I think from everything I have seen and read about this combo.

 

[Newbie solar guy]

I've had my 203 for six months connected to a President Bill with a 2 watt dead-key, using a 102" whip with a Breedlove Stake Pocket Mount. Works great!

Support Rochester .kl2o3 to an Andy2 at 1.75 dead keyUsing a sloper 14' up nice dx , local only 8 miles

 

[Rwb]

i set my lincoln to 4 watts dk am n my 203 is just warm. i go ssb n send about 10 watts n the 203 stays just warm. i have a fan on it but never use it. i did decide 10 watts is needed to keep my 203 locked in

 

[Recon]

Great little amplifier for the money, new they are 75-80 bucks. If you want yours to last turn your dead key down to say 1.5 watts. On SSB I would run 8-12 watts PEP. If you get long winded I would also add a small fan. Here is a nice review below from CB Radio Magazine.

RM Italy KL203P CB Amplifier | CB Radio Magazine

RM KL203-P Amplifier Review The KL203 has been one of those amplifiers I recommend to people again and again over the years. They are inexpensive, they put out a solid 100 watts, which is more than enough for most DX, and as long as you don’t overdrive them they can last for quite a RM KL203-P...

cbradiomagazine.com

I agree! 4-5 watts dead-key will probably shorten the life.

 

[tchr01]

Just a quick followup after having it running for a few days. I had to boost the mic gain for locals, and needed to turn the DK from 1.2-1.5 to get enough carrier to test for SWR on the RadioShack meter. It pushes SSB average to 75-80 / 150 pep but that's still within acceptable limits I think from everything I have seen and read about this combo.

So one weird thing is going on strictly on sideband. I get everything hooked up to the dummy load and adjust my ALC everything seems fine. Consistent 80-100 Watts with 130pep on occasion. Hook back up my antenna, check SWR everything is ok, 1.3. do a couple of tests on a few channels. Everything seems good. Then after the radio's been running for a while, just doing receive, and I go to key up again and test modulation and power, I noticed a dip in the average and peak down about 20 watts. Then if I shut the radio off and turn it back on I'm back to where it was before in good shape.

Is this just a natural function of the ALC? I'm all so curious exactly what is happening when I turn the radio off and back on again? Is the radio just resetting it's max ALC before any modulation starts?

 

[Holydvr]

Doesnt sound right to me. Output should remain consistent if I understand everything you have said correctly. Sounds like something could be amiss with the radio. Hard to know for sure.

 

[Rwb]

I agree! 4-5 watts dead-key will probably shorten the life.

as cheep as they are let er rip n kick up some power. mine been runnibg more than that feeding into it n never gets hot.runs about 15 degrees warmer than the room. i installed a fan on it n it never gets warm nuff to turn fan on

 

[9C1Driver]

as cheep as they are let er rip n kick up some power. mine been runnibg more than that feeding into it n never gets hot.runs about 15 degrees warmer than the room. i installed a fan on it n it never gets warm nuff to turn fan on

If you don't talk much and the amp is not even hitting 20% duty cycle use then yea it won't get warm. If you are in steady conversation and stay keyed down for 20-30 seconds off and on or your telling a story in say 15 minutes it will get very warm. in 30-45 minutes you could possibly fry an egg on the heat sink.

Over the years I have tried 30 plus amplifiers just for fun. I don't care what amplifier it is when your a rachet jaw it will get hot. Combine that with too much dead key and being a long talker and it's egg cooking time. Don't over drive your amp and run a fan are the two best things one can do to help the amplifier out.

The best two amplifiers I had for low heat was a Joker and an X-Force. They were two pill amplifiers built on/in a 4 pill case and heat sink. They were also fan cooled.

 

[Recon]

If you don't talk much and the amp is not even hitting 20% duty cycle use then yea it won't get warm. If you are in steady conversation and stay keyed down for 20-30 seconds off and on or your telling a story in say 15 minutes it will get very warm. in 30-45 minutes you could possibly fry an egg on the heat sink.

Over the years I have tried 30 plus amplifiers just for fun. I don't care what amplifier it is when your a rachet jaw it will get hot. Combine that with too much dead key and being a long talker and it's egg cooking time. Don't over drive your amp and run a fan are the two best things one can do to help the amplifier out.

The best two amplifiers I had for low heat was a Joker and an X-Force. They were two pill amplifiers built on/in a 4 pill case and heat sink. They were also fan cooled.

Also, there are good fans and better fans. Less expensive fans have plastic / nylon sleeve-type bushings/bearings that can collect dust. Fans with sealed ball bearings are the next step up.

 

[tchr01]

Doesnt sound right to me. Output should remain consistent if I understand everything you have said correctly. Sounds like something could be amiss with the radio. Hard to know for sure.

So found out my culprit I think. This 980SSB is interesting the more and more you poke at it. The microphone I was using seemed to be not acting nice with the ALC and with lower power on the radio as a whole. I think the noise cancelling effects of the Ranger SRA-198 were dipping the modulation down far enough to give false readings to the ALC and the radio was just reducing power to stay in "Optimal Levels" for clarity.

SO! Stock mic works fine and consistent, and I guess the SRA-198 is just too aggressive on NC for the 980... which means the SRA goes in the car with my President Andy

The KL-203 has been fantastic so far though with the 980 and very consistent in boosting whatever I give it.