[Boatanchors] Capacitor Needed

[Rob Atkinson]

I have several of the 470 pF Russian doorknobs as bypass caps in my
160/75 m. L network tuner.  I can't remember the v. rating but they
are several KV at least.  I have had no problems and would probably
use them in a transmitter now.

But, two issues:  1.   they are metric, so you need to find metric
brass hardware for them.  I recall getting metric brass nuts and bolts
from McMaster Carr.  2.  My experience was that the tapped collars on
each end of the doorknob twisted off easily.  Maybe I had some
defective ones but don't crank down on them too hard.

Red Ceramite doorknobs:  I am not sure what the problem is here--maybe
there are different types?  I have found 30 KV ceramite doorknobs in
broadcast transmitters, usually two paralleled 500 pF each for DC
blocking at the PA parasitic chokes.   In continuous duty with 1 KW RF
through them at medium wave frequencies they held up.

73
Rob
K5UJ

On Fri, Aug 16, 2019 at 9:30 PM Chuck McGregor <cbmcgr at gmail.com> wrote:
>
> Has anyone tried the  (Russian ??) ceramic doorknob capacitors being
> offered by ebay seller sort57  ?
> Just curious,
> Chuck K7MCG
>