Frank Dresser wrote:

"geojunkie" wrote in message
om...

It's easy to figure how much capacitor leakage would cause an excessive
grid voltage, a reduced screen voltage or plate voltage. It's a simple
ohm's law problem. Don't forget the power leaky bypass capacitors have
to dissapate. Cathode bypasses can get very leaky before causing
problems.

But I'd be surprised if there are any 40+ year old paper caps around
that can meet a fairly loose throw away standard now. Say 1 microamp
per microfarad at it's rated voltage.

What year was your SX 101 made? Mylar caps started showing up around
1960. Even my SW 500 (S 120) had several good quality mylar C-D Black
Cats.

Also, there was an early 60s version of the Sprague Black Beauty which
was paper-mylar rather than paper-oil. The paper-mylar cap was quite
reliable.

Frank Dresser

My SX-122 (circa-1963) has mylar caps'. I haven't changed any of them. I
didn't find any of the paper/oil types. The remaining caps' are ceramic
disc and a few micas. I did change the power filter caps' just to be
safe.
BTW- The SX-122 was the last of the Hallicrafters 'SX' series of
receivers produced under the original Halligan family ownership. The
SX-122'A' (1967-1969) was made under 'Rockwell' management. They
increased the price by $100 without any significant improvements in the
design or performance.


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