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RM Italy KL203 troubleshooting

So I'm finished with this amp... I ended up putting the original transistors back and have about 60 watts out, whatever its enough. I did have one issue I didn't notice until I put the amp on the antenna. My relay was staying latched on after I was done keying. So simple fix was putting a 100k resistor on the cathode of D2 to GND. I haven't tested the audio quality on a receiving radio but the output wave looked relatively clean on the scope. If only I had a spectrum analyzer to verify it :)
 
Interesting, I may have to pick up a book about these and try roll my own. Who knows how long my hack job is going to last.
 
Wait a tick . . . forgot those are MOSFETs . . . not the same thing as AB boiasing with real pills . . . should be fine as is . . . all you need to do with that amp is to make sure that the gate voltage is OK . . .
 
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a little over a year ago I put 4 of the 13n10 fets in a kl-203 for a buddy of mine. his was doing just over 100 on AM and about 175 plus on SSB. he is still running it. 1st time I tried the 13n10's cbman711 recommended them back then. did one other before this one with the irf520's and got just under 80 AM and about 140 on SSB
 
sonoma said:
a little over a year ago I put 4 of the 13n10 fets in a kl-203 for a buddy of mine. his was doing just over 100 on AM and about 175 plus on SSB. he is still running it. 1st time I tried the 13n10's cbman711 recommended them back then. did one other before this one with the irf520's and got just under 80 AM and about 140 on SSB
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What voltage did you set the gate at - BTW?
 
set the voltage at about 3.7. normally on the 13n10 I set them at 3.5 on a radio. the 3.7 worked on the 1st one I did. have not done another as of yet. I have one I just bought that was mounted to a heavy heat sink that has the cover for the radio. the bottom cover. I have not tore it down yet to put mosfets in it. just got it in the mail friday.
 
BBB said:
Original Dave Made amps do not inherently splatter...operators splatter. An original DM SJ will run circles around an RM amp. Not even in the same league and shouldn't even be mentioned in the same post :rolleyes:
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That was a class C amplifier joke. Many people that run Davemades overdrive the piss out of them. They then get that loud blarring overmodulated sounding audio that splatters 15 channels in each direction.

As I recall the KL203 was my favorite cheap little amp. I added a small fan, talked 90% SSB on it with 10-12 watts PEP input. Worked great.
 
sonoma said:
set the voltage at about 3.7. normally on the 13n10 I set them at 3.5 on a radio. the 3.7 worked on the 1st one I did. have not done another as of yet. I have one I just bought that was mounted to a heavy heat sink that has the cover for the radio. the bottom cover. I have not tore it down yet to put mosfets in it. just got it in the mail friday.
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Yeah, it's a good thing that there is a decent heatsink to put those 13n10's on the KL203. Spec sheet says they are good for up to 65W? They can run fairly hot (up to175/C) so long as the heat sink can do it. Wouldn't want to push them too much with gate voltage and drive, I guess . . .
https://www.fairchildsemi.com/datasheets/FQ/FQP13N10.pdf
 
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gate voltage on the 13n10 is 2volts min and 4 volts max. that is why I put them at about 3.5 to 3.7 volts not to over drive it. you have to make sure you get the 13n10 because they make a 13n10L which is a max of 2.0 volts. any thing over that it will blow the 13n10L mosfet.

I like to use them in a cobra 29 ltd because it will do about 50 to 60 watts and not even get hot. I use a temp gun to make sure they do not get hot when I install one in a radio. the IRF520 will normally do about 25 to 40 watts is all. drop the 13n10 in place of the irf520 and it will run a lot cooler also plus more watts out.
 
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sonoma said:
gate voltage on the 13n10 is 2volts min and 4 volts max. that is why I put them at about 3.5 to 3.7 volts not to over drive it. you have to make sure you get the 13n10 because they make a 13n10L which is a max of 2.0 volts. any thing over that it will blow the 13n10L mosfet.

I like to use them in a cobra 29 ltd because it will do about 50 to 60 watts and not even get hot. I use a temp gun to make sure they do not get hot when I install one in a radio. the IRF520 will normally do about 25 to 40 watts is all. drop the 13n10 in place of the irf520 and it will run a lot cooler also plus more watts out.
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Are those the same mosfet s used in strykers
655 and 955?
 

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