[Boatanchors] Capacitor Needed

Glenn Haffly k5zeglenn at gmail.com
Sat Aug 17 08:10:12 EDT 2019


Thanks to all for suggestions
Glenn

On Sat, Aug 17, 2019 at 4:35 AM Rob Atkinson <ranchorobbo at gmail.com> wrote:

> 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
> >
>


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