[Test-Equipment] Sprague TO-6A question

[Ken Kaplan]

Hi Ed,

You got it! I should have looked at the schematic but I think I got a 
bit lazy. Actually I was in the process of recapping a Hallicrafters 
SX-100 & thought I'd test what I had just removed. Looks like I better 
recap the TO6 first. If the test equipment isn't any good, there's no 
point in digging into the radio.

Funny thing is I tested C16 after installing its replacement and it 
looked ok. I measured its value on a digital tester and it was within 
10%. I checked its ESR and found that it was > 99 ohms. So I don't know 
what to think.

Thanks for your help.

73 Ken

k4pf at juno.com wrote:
>
> Hi, Ken
>
> Maybe V-4's grid bypass capacitor C-16 is itself leaky.
> It is a molded paper type, according to the parts list.
> I'd replace it with a .005 disc ceramic.
> 
> I don't have a Sprague TO-6, but do have a good TO-4.
> On my TO-4, I replaced all the paper capacitors,
> most of which were "Black Beauties".
> Surprisingly, the 1952 vintage electrolytics were fine.
>
> 73,
> Ed Knobloch
>
>> Ken Kaplan <krkaplan at cox.net> wrote
> I was trying to test some old 600v paper caps (Black Beauties, etc.) 
> tonight and didn't see what I expected. 
> I got nearly infinite insulation resistance. 
> My really old caps (some from the 1940's) tested as good as 
> some brand new caps I just bought. Hmm - maybe the TO-6 is faulty? I 
> placed a 33 megohm resistor in parallel with a cap and it had no effect. 
> I still had nearly infinite resistance. Then I tried it with a 1 meg 
> resistor - same thing. I was using the L range and following the manual. 
> <snip>