[AMPS] Correction to Henry Ampo Tune Up stuff

[Jim Reid]

Aloha to all again,

Rcvd the following a bit ago:

"-The LOAD control in the 8K-ultra  IS  the Vacumn variable. The vac cap
(465pf-5kv) is in parallel with more fixed ceramic padding caps.

-You have your tune and load knobs reversed somehow., or your
understanding of them."

These wise words came from Jim, VE7RQ.  Jim also wondered  what
happens when I input a drive power of 200 watts;  never have,  but they
did at Henry.  Data I rcvd with the amp shows something over 5 kW out
under such drive power!!  I did put 100 watts drive in once,  not
intentionally.
Burned out two Alpha Delta coax switches and the coils/diodes in my
RF Applications PS-3000 SWR/Wattmeter coupler unit;  had to have
that repaired at the factory.

Have also learned why I wrote as I did about the tune and load controls,
I got the info from the 8K manual schematic!

Now, here is what I now find written in Section 5,  Operating
Controls of my manual copy.

Load Control:  ....a bunch of words.. then" ..provides a signal
to drive a DC servo motor which is connected to the vacuum
loading capacitor." !!    Wow,  now how did I miss that??

However,  back on the 8K RF deck schematic of the manual,  they
have indicated as I wrote,  that's where I got the info I used in
my post.  The schematic clearly shows the servo-motor
operating the vacuum capacitor as the "TUNE" function,  and
similarly the rotary inductor servo is labeled, "LOAD".
I used only their schematic  drawing;  should have read the
manual more closely,  but then I would really have been
confused,  hi.  Guess it should have occurred to me that it
is pretty odd talking about the inductor within the Pi network
being involved in adjusting the load match!  But,  it seemed
reasonable as that one is ganged with the L network inductor
going straight out the feed line.

Oh well, live and learn.  Still wonder if tuning for max out,  or
plate dip for best load is the proper approach.  They are
probably the same at the end!

73, Jim,  KH7M



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