Kl 203 issues

[sp5it]

Test on dummy load. Come back with result.
Could be common mode current or parasitic oscillation issue.
Mike

 

[Shadetree Mechanic]

I have seen a bad output tune send an amplifier into oscillation. Have you used this coax and antenna with an amp before? I have seen a bad coax connector look good with low power, but it will go off the deep end with higher power.

 

[Squints]

I noticed my kl203 doesnt want to unkey itself after transmission if or when my 203 is close or on top my 89xlr but if i move the amp 6 feet away on the same jumper it works just fine and puts out 125 peak drivin 8 carrier swing 20

 

[jdchet]

I always cringe when people run these dual final galaxy radios into kl 203 amps

Maybe I just had good luck, but I ran a 203 behind an old Galaxy 77HML for a few years and never had a problem. Only ran the 77 on low(1w DK) when the amp was on and almost never on AM, just SSB. Always had good reports, SSB and AM, and shot alot of skip, back in the day. The 77 was an older model, circa 1999, so maybe the fact that it had bipolar 1969's in it versus today's mosfets was the difference. The fact that Rolling Radios turned the low dead key down on it might be a reason too. Amp would get warm if I got to ratchet jawing but no smoke came out!
I wish the 77 still worked, but nope! I don't know if I want to pour a whole bunch of $ into a 20+ year old radio.........

JD

 

[Shockwave]

Anytime the RF sniffer circuit holds the relay keyed after the radio is unkeyed, that amplifier is oscillating. It is the RF generated by the oscillation, that holds the relay keyed. Anytime you have a single push-pull RF stage that has to use four transistors, you know the manufacturer has used the entirely wrong transistor. This greatly contributes to instability, self oscillations and premature failure. You don't use four, 25 watt transistors to make a 100 watt amplifier. You use two 100 watt transistors to make a 100 watt linear.

 

[9C1Driver]

Maybe I just had good luck, but I ran a 203 behind an old Galaxy 77HML for a few years and never had a problem. Only ran the 77 on low(1w DK) when the amp was on and almost never on AM, just SSB. Always had good reports, SSB and AM, and shot alot of skip, back in the day. The 77 was an older model, circa 1999, so maybe the fact that it had bipolar 1969's in it versus today's mosfets was the difference. The fact that Rolling Radios turned the low dead key down on it might be a reason too. Amp would get warm if I got to ratchet jawing but no smoke came out!
I wish the 77 still worked, but nope! I don't know if I want to pour a whole bunch of $ into a 20+ year old radio.........

JD

This part of your statement is a bit off. "Only ran the 77 on low(1w DK) when the amp was on and almost never on AM, just SSB." When you use SSB there is no dead key, it's all modulated watts.

I think the reason you were fine is the SSB peak watts on Lo were probably 6-8 watts, then maybe 18-20 on med, and 25-30 on hi. So for the KL203 with your 77 set on Lo on SSB that was the perfect drive.

I remember that Rolling Radio's guy, he was big on the old X-Force forum. He used to mail all his difficult work to Key CB in Warren,IN. Jim would fix stuff up and send it back to him.

 

[Squints]

Well thanks for all the wordds that didnt help my situation at all

 

[nomadradio]

I noticed my kl203 doesnt want to unkey itself after transmission if or when my 203 is close or on top my 89xlr

Occam's razor says that all things being equal, the simplest explanation to a puzzle is most likely the right explanation.

Would be nice is this were always the case, but you did say that all you had to do to change the amplifier's behavior was move the coax cable between the radio and amp.


Kinda points to a loose ground connection to the coax shield in one or both of the connectors on your coax jumper.

Quickest way to judge this is to attach the jumper to a dummy load. Turn up the receiver volume and shut off all the ANL or NB switches. Wiggle the coax behind the plug at each end. If you hear any change in the noise level in response to that, the shield connection is not good enough. And a poor ground connection between the radio and amplifier is a time-proven way to make an amplifier unstable.

73

 

[ChristopherDLong]

I noticed my kl203 doesnt want to unkey itself after transmission if or when my 203 is close or on top my 89xlr but if i move the amp 6 feet away on the same jumper it works just fine and puts out 125 peak drivin 8 carrier swing 20

you have an unstable amplifier. there is a well known hack that makes these amps seem to put out dubble there power. it really doesn't but it shows 125 ish on a meter.

solder the leg of the big resistor back into its pad. you really really don't want to run a mosfet amplifier with the filter cut. you still only make around 80 watts on channel either way.

 

[Chris Lawrence]

You can buy just the kl203 boards fully populated ready to fit into the existing case.
A bit fiddly but much cheaper.

Yes, the AD-203 boards with a heat sink that normally takes the place of the internal speaker.

I used to buy alot of them from DnJ Radio. Not sure if they still have them but they’re cheap.