[Heathkit] Tubular Ceramic Capacitor

[Heinz Breuer DH2FA]

I have not seen any tubular ceramic capacitors offered for sale in 
decades. They were widely used in German equipment 50 to 60 years ago 
and probably earlier as well.
They consisted of a small ceramic tube about 3 to 4mm thick and up to 
30mm long depending on capacitance. The "capacitor plates" were vacuum 
metallized to the tube on the inside and outside. Leads were brazed to 
it. The outside lead had two turns over the tube. The whole assembly was 
then painted with a thick paint (mostly stone gray) to secure it all 
probably by dropping it into the paint bucket.
Tubular ceramic capacitors were available with different temperature 
coefficients to allow a free running oscillator to be on frequency over 
a wide temperature range. The temperature coefficient was indicated by a 
colored spot on the body of the capacitor.
Inventions in ceramic materials with different temperature coefficents 
were made in the thirties. Germany had no raw material for making 
crystals. All Wehrmacht equipment depended on free running temperature 
compensated oscillator circuits.
vy 73 Heinz DH2FA, KM5VT


Steve Sutfin wrote:
 > Hello to the list,
 >  Has anyone heard of these or know of a source? I need a 3.3pf/500v.
 >