[Heath] More Marauder problems

[Alexander N. Gerli]

Hi, folks,

Well, after checking the relay out as closely as possible (magnifying
glass), I decided to very carefully lube the pivot pins for the relay
'tongue'. I used some LiquidWrench penetrating oil and a sharp knife edge to
drop the lube onto the pivot pin on each side near the armature. Also,
decided to check the plate voltage on V9B. It is right on at 350.8, hard to
get better than that.

Now, the relay has been mounted back onto the chassis and it latches sharply
rather than gradually as before. Now another problem has surfaced. Before I
could get 75W out into the DL with the drive level about 50%. Now,there's
nothing at all and the tune and load controls have no effect. Worse yet, the
plate current (aka 6146 cathode voltage) is pegged and there's no dip or
anything.

I have replaced the .125 ohm 1/2W precision resistor R39 with a pair of .25
ohm Caddock flatpack resistors in parallel. Fits perfectly and those are
probably 1 watters each. Also replaced C75, the .005uF 1.4kV cap at the base
of the plate choke. That was a failure item in the ICOD section and it
looked like it had a weird bubble on it, so I considered it shorted and
replaced it with a 1.6kV one I had from the PA of a parts-car SB-101.
There's also C76, the .001uF 2kV Micamold from the plate choke to the PA
Tune cap. Just doesn't seem to me that it would fail suddenly, but if it
were, the whole PiNet would be a mess. Haven't replaced that yet.

Something's really wrong with the high plate current on keydown, and that's
with the 5R4 HV rectifier out of its socket. Tried to neutralize the PA
using the VTVM method and got no voltage at the PA out jack. The Driver Tune
doesn't produce any grid current, but with the drive level backed off, I can
get a peak in the Plate Current with the Driver Tune control. So, the Drive
Tune has some effect. Just not when you're measuring grid current.

I don't know where to look next.

73,

Sandy AC1Y

Alexander N. (Sandy) Gerli
'Corgi Cottage'
548 Allred Mill Road
Mount Airy, NC 27030-2202
919-625-7181

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