[Amps] mica condensers

[Roy Koeppe]

Was asked,

"Hello, I have two capacitors, NOS both, manufactured by Soshin Denki
K.K.,
one is Type A-2, 0.01uF, T.V. 5 KV DC, and a stamped number (date code?)
61-8.
The other is Type A-1, 0.01uF, T.V 3 KV DC. the ¿date code? is 62-3.
Both +- 10%.
Are these useful for +B decoupling (bottom's plate choke decoupling)?,
upto
2500 V operating voltage?. Any other test precaution?."

Thanks in advance
Best regards
Guillermo - LU8EYW.


Hi Guillermo,

One of my engineering handbooks states that mica capacitors are not
suitable for use where there is a continuous HV DC potential present
across them. It warns that a type of molecular migration occurs,
degrading the capacitor. Save those for an alternative application, such
as coupling into a grounded grid cathode stage. Use cheaper, ceramic
disc caps or door-knobs for 'lowly' bypassing duty.

73,   Roy    K6XK/0