RM 203 Questions..

[CB590]

Just got one in for $69 and shipping from Cooper.. The printed sheet says 28-29.7 MHz on it. I turned down my 10/12m to 1.5w dkey and with meter inline after amp I get 25w dk or so.. Which matches the videos on this. The RM site says a wider range like 18-30mhz. Any cause for concern? Or if its working (putting out power on my meter) on both bands just be happy??

 

[Tallman]

No you are good just don't overdrive it or swing too much. I have repaired so many of those because someone drove it with a souped up radio and killed it.

The jumper nomad mentions is listed as J3 in the schematic at the top of the drawing.
Just remove the jumper and see if that works if not it needs to be on pins 2 and 3.

 

[nomadradio]

Importing an amplifier like that and selling it require that you somehow get around the FCC rules that ban small amplifiers on 11 meters.

For the first ten or more years, you had to move a jumper inside from one pair of pins to another. Wouldn't key until you did. We got told that this made it legal to import into the USA.

Later on they seem to get lax about this and just sell the thing ready to use.

The RM site's description should be trustworthy. That "28-29.7" description is to avoid harassment from the FCC, since those frequencies are in the 10-meter ham band. It's legal to use an amplifier on those frequencies.

The FCC has been all over the map, enforcing the linear prohibition one year, ignoring it the next. What you can and can't get away with is not the same now as it was when the RM amplifiers first appeared on the market.

73

 

[9C1Driver]

Just got one in for $69 and shipping from Cooper.. The printed sheet says 28-29.7 MHz on it. I turned down my 10/12m to 1.5w dkey and with meter inline after amp I get 25w dk or so.. Which matches the videos on this. The RM site says a wider range like 18-30mhz. Any cause for concern? Or if its working (putting out power on my meter) on both bands just be happy??

I think you mean Copper.

 

[CB590]

Importing an amplifier like that and selling it require that you somehow get around the FCC rules that ban small amplifiers on 11 meters.

For the first ten or more years, you had to move a jumper inside from one pair of pins to another. Wouldn't key until you did. We got told that this made it legal to import into the USA.

Later on they seem to get lax about this and just sell the thing ready to use.

The RM site's description should be trustworthy. That "28-29.7" description is to avoid harassment from the FCC, since those frequencies are in the 10-meter ham band. It's legal to use an amplifier on those frequencies.

The FCC has been all over the map, enforcing the linear prohibition one year, ignoring it the next. What you can and can't get away with is not the same now as it was when the RM amplifiers first appeared on the market.

73

Its the new one with blue switches.. I'd open it up to check it out but the bottom cover isn't sliding at all..

I noticed as I adjusted my dk from 1.5w to 2w the amp moved from 20-25 up to about 30w..

Leaving it at 1.5w dk.. Will do some live testing today..

 

[CB590]

Works great on test this morning. Many easier contacts further out than normal

No adjustments needed.

 

[Big Kahuna]

The first RM amps I bought needed conversion (pre-2005 I think) but all the ones recently worked right out of the box. That KL203 will like 1w to 1.5w deadkey and swing from there. For AM as long as you keep the deadkey down low they will last a long time. On SSB I've even used them with dual final radios - RCI2950, Lincoln II, etc and even swinging 40w into them they worked great and had no issues although they are best suited to a standard CB. With your McKinley just set the RF power at low (1 to 1.5 watt) and you should be able to use that combo for years. When talking on SSB you may want to set the RF power back up to max to see a good 125W out of the amp - JUST DON"T FORGET to turn the RF power back down when you switch back to AM you don't want to key 4 watts into a KL203 for extended periods of time by accident.

 

[9C1Driver]

The first RM amps I bought needed conversion (pre-2005 I think) but all the ones recently worked right out of the box. That KL203 will like 1w to 1.5w deadkey and swing from there. For AM as long as you keep the deadkey down low they will last a long time. On SSB I've even used them with dual final radios - RCI2950, Lincoln II, etc and even swinging 40w into them they worked great and had no issues although they are best suited to a standard CB. With your McKinley just set the RF power at low (1 to 1.5 watt) and you should be able to use that combo for years. When talking on SSB you may want to set the RF power back up to max to see a good 125W out of the amp - JUST DON"T FORGET to turn the RF power back down when you switch back to AM you don't want to key 4 watts into a KL203 for extended periods of time by accident.

Ouch, I would strongly recommend not running 40 watts PEP into any version KL203, red or blue. I have had two of these and for the money they are great as long as you add a fan and don't over drive them. Since they are a light duty amplifier to keep heat down on SSB run 10-14 watts PEP into them and they will work great. If I was long winded I would drop the power down to even 8 watts. I found that bumping the drive level up to 18-20 watts would cause the amp to heat up fast.

 

[Robb]

Besides heat - which is an important factor - the harmonics you create by running an amp out of recommended input watt range will make it easier for you to get noticed by Hams. Ever get an 'OO' card in the mail yet? If your station is really noisy, an 'Official Observer' Ham will put you on notice. This is not good attention; this is asking for trouble.

Harmonic watts are't even on the channel you are broadcasting on; they end up all over the spectrum - and this sets you up for trouble.

Just because you are fishing for a few extra watts output, you don't want/need to make yourself a beacon for the FCC or OO to be interested in you. Run it clean and maximize your antenna, and you can still be the 'tallest hog in the trough'.

Needed to be said . . .

 

[Big Kahuna]

Ouch, I would strongly recommend not running 40 watts PEP into any version KL203, red or blue.

I don't recommend it either but a lot of people seem to think these things are more delicate then they are. They do heat up quickly if driven too hard, but of all the different KL Amps I've touched (probably 12-15 by now) , I've only even had 1 fail and it was the KL60 that I gave to a friend and he used it with a radio with a 4 watt deadkey for year and then it finally died.

The main key to long life for these is to keep the AM deadkey low. As stated they work best with low deadkey and swing from a single final CB that's doing anywhere from 10W to 18W. On SSB they can handle any single final CB no problem.

I also much prefer the KL203 to the larger RM transistor amps which I never felt seemed to be worth the extra money. At it's price it really is the best bang for someone buying their first amp to pair with their CB, and for anyone else who just needs a little extra juice.

Robb is right about overdriving that's why your McKinley paired with that amp is a great match, even at max output on AM/SSB you won't be pushing it too hard.

Only cards I've ever gotten from hams are QSL cards

 

[kopcicle]

Just to clarify
Intermodulation Distortion Products...
These are created as sums and differences of your audio bandwidth and occur on and near your transmitted signal.
IMD 3, 5, 7, 9, ...
Harmonics...
Even, odd and combinations of each of your transmitted frequency.
54, 108, 216...
54, 81, 243...
Combinations ad nausea of both.

Now that that is clear as mud (apologies to the real tech savvy I drastically over simplified)

The frequency response of your input.
As near a "flat" response as possible. All frequencies in your voice range amplified equally.
Low total distortion in the system.

Then deal with stage gain in the radio as well as the amp.

simple enough ?

 

[CB590]

Good contact about 30 miles away. Said I was clear sounding. He was running a TS amp with like 250w or so. Nice to able to flip a switch and 'get out' a little better over the din.. I agree it's a good mate to most rigs when they are set low.. Others said I was clear sounding as well and asked about my radio.. Very happy with it. HY left bad taste.. Copper did fine by me on this. Got in just 2 days.

 

[Sarasota Slim]

I've been happy with my 203. If it died today, I'd probably go on and get another one.

 

[codeman]

I've had my little 203 for about 3 or 4 years now and I've pushed that amp way too hard getting long winded and it is still going strong. Best $70 I've spent in radio equipment.

 

[sonoma]

those little amps are cheap to repair also. i normally find the finals blown in them and you can put fqp13n10 in them as a drop in and they will give you a little more output than the stock ones. the other item that I have had to change once was a relay in one. my buddy has ran one for about 15 years now and only popped the finals one time by running it with his 2950 on high power. as long as he keeps it on low it works just fine. those 4 mosfets cost just under 50 cents each in most cases.