"geojunkie" wrote in message
om...

This is an SX-101a that I believe is near 1962, as the knobs match
later receivers like the SX-115 and SX-117. The paper caps are pink
Tiny Chief 600v, and molded black caps that are marked only with
stripes... no lettering of any kind. I do see a "P" molded into tiny
circles on one side and a "2" in similar circles on the other side.
What brand of black caps are these? The parts list calls them both
paper caps and never mentions mylar.

The striped caps are probably Sprague Black Beauties. I have some Black
Beauties and all have a 2 molded in recesses on one side, and various
letters molded in recesses on the other side. If one of the
capacitor's leads are soldered into a nipple on one side, they're oil
filled.

I don't know about the SX 101's part list, but I do know the term "paper
capacitor" lasted into the 70's as a generic term for film capacitors in
such technical writings as the ARRL Handbook.

Sounds like you would tend to
replace them all based on this. I have been using tubular
polypropylene 630v for replacements, the yellow ones. I notice some
seem to love the orange drops. Is there a difference worth worrying
about?

I'd probably crack one or two open for curiosity's sake. Mylar is quite
clear and paper is translucent brown. If they turned out to be paper,
I'd double check my testing procedure. Paper caps had detectable
leakage even when new.

If they are paper, I'd change them. If they are mylar, I wouldn't worry
unless troubleshooting pointed out a problem.

Either the Orange Drops or the yellow caps are excellent replacements.
I prefer the yellow caps because they are a bit more compact and they
have longer axial leads. They are usually easier to work with. I'm not
sure the yellow polyporpylene caps you have are the same size as the
yellow mylars I like, however. The only problem with the yellow caps is
they aren't resistant to a hot soldering tip. No problem, once I
learned to be careful.



I did find a 10w wirewound heater located under the RF amp, mixer and
1st osc tubes that was almost shorted and most of the components over
it are discolored. This thing is about 6" long, I think I will put a
string of maybe three new power resistors of 1/3 the value in the
metal casing and hope this distributes the heat evenly enough. This
heater is on line anytime the receiver is plugged in, as is the
oscillator filament.

A wirewound almost shorted? That's odd. I don't know the details of
the SX 101, but I'm wondering if the resistor is there as a temperature
regulator. If so, it might have a high positive temperature coefficent,
and it's cold resistance would be much lower than it's hot resistance.

Frank Dresser