Skip to content

YO5PBG Wavelenght

Amateur Radio, QRP, Home Made

An unknown called me a month ago giving me an RM Italy  KLM-60 CB Power Amp. (25-35 watts @ 12 volts) to repair this PA.

Unfortunately the RF trasistor was blown and I didn’t know what type it is. The marking was not visible. On the schematic, the transistor is RM-3 type…. That is…. ???????

After I found that it looks like an IRF5XX series transistor, also a Mosfet transistor, i bought 3 IRF530 transistors.

One for testing on this PA, 2 for personal testing use.

I was amazed.

With 20V/50 ohm input (4w) i obtained 25 watts RF (50V/50ohm) @ 27-28MHz with only 13V supply.

After a while I called him to tell him about this. He told me that he found that the antenna is more important and he want to buy I better tranceiver with more power, so he is giving me the amp, for free.

I modified the circuit for wide band input and otput. with 10Volts @ 50 ohms (1W) i have a constant 50V output (25watts) across HF – from 160 m to 10 m band, at only 12,7 – 13Volts supply.

No heatting.

%d bloggers like this: