[SCCC] Capacitors - Caveat Emptor

Art K6XT k6xt at arrl.net
Wed Jul 28 17:22:35 PDT 2010

Mouser just delivered me some 500V 240uF screw terminal electrolytics 
for my Alpha 76PA.  Your first question will be "why 500V?". Because it 
uses a Peter Dahl 3CX800 transformer running about 2800V no load. Which 
also enumerates why I needed new capacitors. The six 450V units took the 
abuse for three or four years before spitting their guts on the PC board.

So what is this. 500V caps of this configuration are apparently not used 
much. Several suppliers list them, none of which except Mouser had any 
in stock. Mouser had 5. Number 6 took 6 months for Mouser to get and 
send to me.

What gets me ornery about it is this. For the entire 6 months C-D had 5 
units on a shelf in South Carolina. Could I interest anyone, cost be 
damned, in snagging one of these for me? Will C-D sell direct to me at 
any price? Despite numerous pleas, not a chance.

The moral of my sad tale is this: If you plan (hi!) to blow up your 
similarly situated amp, plan ahead ordering those caps!

Yep. I could have hacked the ckt board to haywire in a seventh 450V. 
Chose not to. Instead I bought a spare amp so I'd have a spare in the 
event and also so I'd have an instant on. That three minutes has always 
been a DX'ers bother.

73 Art
Allison, Colorado
"Whether you believe you can do a thing or
not, you are right."  --Henry Ford.

More information about the SCCC mailing list