[Hammarlund] SP600 and BBODs

[Kenneth G. Gordon]

Wes:

Checking capacitors with a VTVM will not tell you how they operate under full voltage. Your 
VTVM applies maybe (a big "maybe") 1.5 VDC to them to measure their resistance.

I have several "condenser checkers", and capacitor checkers here, all of which apply full 
working voltages to capcitors at voltages up to 600 VDC.

Two of mine are the ancient Heathkit C-3 which I have rebuilt, one is a copy of the Sprague 
TO-5. I don't have a "megger" yet, but plan to build one. They all work very well, and I use 
them religiously. I rely on them, and they have never let me down.

250 V capacitors that test "good" at 25 VDC, show very, very serious leakage at 250 VDC, 
and some even suddenly short out at their "normal" working voltage when tested on any of 
my cap checkers.

I wouldn't trust even ONE of those darned BBODs anywhere!

If you don't have a real cap checker, you can "synthesize" one by  connecting a capacitor that 
you want to test in series with a milliammeter and a variable HV DC supply, then start 
cranking up the voltage.

You can watch the current climb as the voltage goes up.

There are collections of data which show the allowable leakage of any capacitor and you can 
use those if you want to, but if there is more than a microamp or so of leakage in a 250 V 
capacitor, that is way too much..

If it was me, I would simply yank all of those damned things and toss em. I wouldn't bother 
testing them. All of us have had experiences with those BBODs, and all of those experiences 
have been bad.

But its your receiver and you can do what you want to.

Ken W7EKB