[Amps] door knob capacitors

[Gary Schafer]

Hi Glen,

Interested in the parameters on the GI-7B tubes. I have a pair here to put
together.

What plate voltage do you have on them?
How much plate current?
How much bias?
Plate idle current?
Grid current?
Drive power?
Output you said was 700 watts.

Thanks,
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
> On Behalf Of Glen Zook
> Sent: Monday, February 28, 2011 11:06 AM
> To: amps at contesting.com; DJ7WW
> Subject: Re: [Amps] door knob capacitors
> 
> Basically, the other door knobs that I obtained for a VERY good price
> were 20 kV!  Definitely overkill.
> 
> I "solved" the problem by putting 2 0.01 mfd capacitors in series with
> the 1400 pf door knob fixed loading capacitor.  This got the effective
> value of the 1400 pf down to just under 1100 pf which, in turn, got the
> loading at 50 ohms impedance almost in the middle of the air variable
> range.
> 
> Being that I am a firm believer in the principles of the conservation of
> my finances and labor ("cheap and lazy"), I had the 0.01 mfd capacitors
> in stock and therefore used them.  I do need a high voltage transformer
> that is just a little bit heavier than the one that I had in the junque
> box.  That one has just a 120 VAC primary and I prefer to run my linears
> from 240 VAC.  Also, the voltage is a bit lower than optimum and I want
> to eventually run between 200 and 400 volts more on the plates of the
> GI-7bT tubes.  However, I did use the linear this past weekend during
> the CQ 160-meter SSB contest and it worked very well.  The output was
> right at 700 watts which is a great improvement over my "normal" 60 to
> 70 watts output.
> 
> Glen, K9STH
> 
> Website:  http://k9sth.com
> 
> 
> --- On Sun, 2/27/11, DJ7WW <dj7ww at t-online.de> wrote:
> 
> Why do you want at least a 10KV rating while the capacitors will not see
> more then 500V? More important is to select a RF doorknob with low TCC.
> 
> 
> 
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps