Apache High Plate Current

[Brian Wood]

Rich,

After thinking I had fixed my grid current flicker by replacing the 47 pf
capacitor that serves as the load for the final grids, I think I have now
found that the flickering is related to the ground wire that runs along the
side of the bracket-mounted driver tuning cap in the DX-100. If the Apache
is built in a similar fashion, you might watch out for capacitive coupling
from your driver tube to nearby grounds. The driver in a DX-100 is a 5763.
Course, it could also be a bad contact in the 5763 tube socket. The
flickering seems to stop when I angle the tube away from the ground wire,
which of course affects the connectivity to the socket too.

73,

Brian, W0DZ

-----Original Message-----
From: Heathkit Owners and Collectors List
[mailto:HEATH at LISTSERV.TEMPE.GOV]On Behalf Of Rich Sahlender
Sent: Sunday, December 15, 2002 9:52 PM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: Apache High Plate Current


After several years on the shelf I finally got around to
working on my TX-1. Won't bore you all with the little
details of the clean up but found a nearly new pair of
6146B's in the final cage which I promptly pulled and
replaced with 6146's. Didn't have time to neutralize
them yet but tried loading into a dummy load to see how
it acted.

I have more than enough grid drive on 80m which "looks"
steady by the meter and just about the recommended 6ma
on 10m but it randomly moves plus/minus about 1/2ma
which in my experience is a pretty clear sign it needs
to be neutralized. What is unusual to me though is the
high plate current. Manual recommends 250ma.

On 80m with no loading and 6ma grid drive the plate
dips at 300-350ma and only about 70 watts out. On 40m
I have to back the grid drive way down or the plate
current goes off scale. About 1ma grid drive with a
little loading and the plate dips to 250ma with only
50 watts out. At 3ma I get about 100 watts out but the
plate current is pushing 400-450ma...

Would finals in need of neutralization also cause
symptoms like these? I've never seen it quite like
this... or should I be looking for bad rf bypass caps
and/or meter shunts etc?

tnx de Rich WA3WLH

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