[Boatanchors] Mil-Spec capacitor temp coefficients?

[Philip Atchley]

Hi All,

The 'first' of the two SP-600's (A R-274C) that I recently refurbished (not 
the basket case I just rebuilt) had a "frequency jump" with thumping the RF 
deck/tubes.  Finally I "shotgunned" the RF deck, replacing all the ceramic 
capacitors etc that are in the oscillator circuit since it isn't at all easy 
to pull the deck for individual component replacement.  There are two 
capacitors right across the coil contact wipers that are labeled as 
"Temperature compensation".  These were replaced with Silver Mica as it is all 
I had at the time.  Now the set does have a little more temperature drift than 
I would expect it to, but it doesn't have the frequency jumping anymore.

Next time I go in that deck I'd like to replace those two capacitors with 
correct, or at least nearly correct units, but I'm not certain of the actual 
coefficient, I.E. N330, N450 etc (I assume it's a negative coefficient, but 
not sure of the amount).

Here is the specs from the manual on these capacitors.  Can anyone "decode" it 
for me?  I know they're 5pF ceramic units, but that's about all I know.

Capacitors C79 and C80.
5pF +/- .25pF, 500VDC.
JAN CC21UJ050C

73 de Phil,  KO6BB
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