{Collins} Re: KWM380 PA Transisitors



Jim, MRF421 is the one to use, how's the HRO 600 percolating? My 600 is making great espresso.
 
73's, Mike

"Dr. James C. Garland" <4cx250b@xxxxxxxxxx> wrote:
Gang, I?m repairing a KWM-380 for a local radio club and find that the output transistors are bad. They?re Motorola SFR3030P devices, which are long out of production. I know this has come up before, but I?m not sure what appropriate replacement transistors are.  I  _think_ it may be the MRF421, but am not sure.  Also, the MRF422 (similar, but intended for 28V) might work, but that?s just a guess. Can someone who has actually replaced the PA transistors provide me some guidance?
 
BTW, the reason the output transistors are blown is because the previous owner reversed the plus and minus power supply leads to the output stage. This put a negative voltage on the transistors and blew their base-emitter junctions. Pretty dumb, no?
 
73,
 
Jim W8ZR



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