Apache High Plate Current

[Rich Sahlender]

I did adjust the clamp circuit, I did not check anything in the
metering circuits. After cleaning/working it all weekend I only
did basic voltage checks after slow power up with variac to make
sure B+ and bias was reasonable in a few key places. I ran out
of weekend before I could do any detailed measurements. I'll
continue next weekend but thought I'd ask here and plan my work
based on responses from the list.

tnx de Rich WA3WLH

On Mon, Dec 16, 2002 at 11:14:48AM -0500, Peter A Markavage wrote:
> Have you checked and/or adjusted the clamp circuit as per the setup in
> the manual? Did you check the .1 ohm meter resistor for the plate
> current? Besides neutralization issues, high or runaway plate current may
> be a function of the clamp tube circuit.
> Pete, CWA
>
> On Sun, 15 Dec 2002 23:51:49 -0500 Rich Sahlender <rsahlen at VOICENET.COM>
> writes:
> > 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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