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RM Italy KL203 troubleshooting

Might check to see if the input coupling cap hasn't popped from too much input power. Not likely; but possible . . .

Are you referring to capacitor C1 in the relay circuit? That is good as the relay does close with RF applied and I did test the relay contacts to be good.
 
No.
There is a coupling disc cap right at the input.

I haven't worked on a lot of amps; just a few.
Simpler than an SSB or export radio by far.

I worked on a dual 1446 pill amp a couple of years ago. The problem? Someone tried to push 100+ watts into the input. Checked the pills; no problem. Happened to glance at the input cap, and I saw a burn hole thru the side. Replaced it and it worked fine. Not a common fault; or maybe it is. Any time someone wants to put more power into the amp than it was designed for and something will snap. Glad it was a $1 part and not $50 worth of parts. Good thing it was a silver mica cap and not a ceramic disc cap. But it wouldn't surprise me if a ceramic will puke its guts if too much power is supplied. Lack of experience on my part; but think it can too . . .
 
No.
There is a coupling disc cap right at the input.

I haven't worked on a lot of amps; just a few.
Simpler than an SSB or export radio by far.

I worked on a dual 1446 pill amp a couple of years ago. The problem? Someone tried to push 100+ watts into the input. Checked the pills; no problem. Happened to glance at the input cap, and I saw a burn hole thru the side. Replaced it and it worked fine. Not a common fault; or maybe it is. Any time someone wants to put more power into the amp than it was designed for and something will snap. Glad it was a $1 part and not $50 worth of parts. Good thing it was a silver mica cap and not a ceramic disc cap. But it wouldn't surprise me if a ceramic will puke its guts if too much power is supplied. Lack of experience on my part; but think it can too . . .

Thanks for the suggestion, the only cap on the input of this amp is across the input transformer primary and appears to be physically intact.
 
input cap.PNG Perhaps a diagram will explain my point. In the red circle at the amp input is a coupling cap. That can pop. Without continuity, no workee. Been there; seen that . . .

input cap.PNG
 
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RM Italy has a new line of accessories for their amplifiers. These can be used at any time and are available in various colors and styles to suit your personal taste.

HWtgjhr.jpg
 
Heeey I fixed it, and guess what it was. The freaking relay. I bought another one off digikey just in case because I saw another thread with the top blown off the relay. I replaced that first and i got 60 watts out (before was <2 watts). The funny thing is the relay ohmed out fine, the relay coil was even about the same resistance as the new one. For $3 i cant complain. Relay PN V23105A5303A201

But I bought 10 IRF520N's so I decided to put them in and well now I'm down to like 25 watts..soo. Do I put the old fets back?
 
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But I bought 10 IRF520N's so I decided to put them in and well now I'm down to like 25 watts..soo. Do I put the old fets back?
Get some ERF2030 fets or try to boost the bias a little bit. The old fet's were weak and I don't think heating them up helped.
 
I heard they were improving the product line but I had no Idea!!!!!! Too Funny!
RM Italy has a new line of accessories for their amplifiers. These can be used at any time and are available in various colors and styles to suit your personal taste.

HWtgjhr.jpg
 
Get some ERF2030 fets or try to boost the bias a little bit. The old fet's were weak and I don't think heating them up helped.

It looks to me that R2=10k and R3=3.3k are a voltage divider for the bias circuit and the output is set to about 1.86 Volts... The threshold voltage for the IRF520N is 2-4 volts. So im thinking that I can put a 10k pot in there and tweak it until I regain the power lost. What do you think?
 
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It looks to me that R2=10k and R3=3.3k are a voltage divider for the bias circuit and the output is set to about 1.86 Volts... The threshold voltage for the IRF520N is 2-4 volts. So im thinking that I can put a 10k pot in there and tweak it until I regain the power lost. What do you think?
Are you seeing the right amount of output power already?
 
It looks to me that R2=10k and R3=3.3k are a voltage divider for the bias circuit and the output is set to about 1.86 Volts... The threshold voltage for the IRF520N is 2-4 volts. So im thinking that I can put a 10k pot in there and tweak it until I regain the power lost. What do you think?
I would use a 10 Kohm ten turn pot in place of R2 and tweak it slowly.
 

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