You are not going to read anything with a low frequency C meter such as the
AADE, trying to measure the plate tune cap with the plate choke in the
circuit. The choke will look like a short at the low frequency.
The only way to measure plate tune C with the plate choke in circuit is to
use a C meter that does it "on frequency of interest". Otherwise you must
disconnect the plate choke.
73
Gary K4FMX
> If you are using a low frequency C-meter such as the AADE unit,
> disconnect the plate
> choke lest it throw the C measurement off.
>
> ## here I disagree. The effect of the plate choke is ALREADY factored
> in ..on the
> spread sheet. My 200 uh plate choke will..'eat' 40 pf from my Tune
> cap on 160m.
> That effect can be seen right away, when plate choke removed. With
> choke removed,
> the tune cap has to be REDUCED in value by exactly 40 pf. Change the
> value of the
> plate choke on the spread sheet, and you will see the effects on the
> value of the
> tune cap asap. Huge difference between 20uh, 200 uh.. and 99999 uh. [
> 160m]
>
> ## to recap... the tube adds another 33 pf..... but the 200 uh plate
> choke 'eats'
> 40 pf. [160m] On the higher bands, the plate choke has a small
> effect.
>
> ## if the LCR meter. or what ever u use.. is more accurate measuring
> caps... yes,
> I would tweak the tune cap with it [ including tube and plate choke].
> Then use the same
> lcr meter to get the coil tap in the ballpark. Then tweak the coil tap
> and load cap to resonate.
> I used to use a loaded Q of 12 [ = 10 using the old arrl/orr/eimac
> method.. which is just input
> Q and not total Q] , I now use a loaded Q of 8-10. Eff improves,
> less coil and band switch
> heating, amp requires less adjustment, once tweaked at 14.200..... it's
> good from 14.100 to
> 14.300 . Harmonic suppression might drop a bit, but the ant's are
> monobanders, and swr on
> the 2nd harmonic is sky high.... or is not inside a ham band. My 40 m
> yagi does not resonate
> on either 20m or 15m. I still use a LP filter.. with a 33 mhz cut
> off.
>
> later........ Jim VE7RF
>
>
>
>
> 73, Bill W6WRT
>
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