In article , - - Bill - -
writes:

had one many, many years ago and it was a good rig. I seemed to have
a persistent problem with popping diodes in the bias supply but that may
have been 'my' problem.

I think mine has the original bias supply diode. I measured the bias voltage
and it adjusts over a wide range.

I *did* find out that the other diodes in there were just replacements for the
low-voltage B+ supply, 375V or so. Four diodes in series-parallel. No idea
what the original was, other than Moore's book entry.

Will have to go up in my attic and break into the Rectifiers box to hunt up a
5R4. No wonder the wiring was intact around the socket. I guess the cathode
current I was reading was just screen current plus grid drive.

Mine had a regular Amphenol mic connector - dunno if that was original
but I didn't need PTT anyway :-)

Mine is what you'd probably call a single-pin Amphenol -- a big screw ring with
a hot contact in the center. I have some signal generator probes like that.
(The real problem is with my Ranger, whose Amphenol has two hot pins inside the
screw circule, one for PTT as you said).

With all the adjustments provided, the VOX inthe HX-50 should work well. It's
nice that it has a built-in antenna relay -- would be a nice match with my
HQ-160 or 180 (though I'd rather use the 180 for AM).

BTW, who designed that function switch -- you have to go thru the MOX (on)
postion to get from STDY to TUNE (CAL). Not the first nor last poorly laid out
rotary switch, but darn, this is a Hammarlund...

I wound up changing to 6146 just for the heck of it...no real difference.
It tunes up easy...assuming its neutralized just tune for max output.

Glad to hear that a 6146 drops in. I was thinking the 6DQ6 in there was a
seep tube, but the power trans' AC is over 800V and sweep tubes are usually
lower, IIRC.

But the 6146 pinouts and heater voltage will match OK?

I haven't cracked the PA cage yet (did Hammarlund own their own screw factory?)
but I trust there's a neatralizing cap in there.

What's the purpose of the nice air trimmer cap in the relay compartment below
the PA?

You really can't tune it up wrong. I recall it being persnikety about
the 6AW8 and 12BY7 (I think they were) having the tube shields firmly in
place - not unexpected.

Well I know I'm getting drive thru those -- turning up the Drive draws more
(screen) current in the PA. The shields are pretty rusty, but I have some
spares handy. Drive tuning is broadband per band, so assuming the coil slugs
are set right for each band, you are right, the tune-up should be easy.

Some rigs (like Viking II or KWM-2) are really paranoid about drawing too much
grid current, especially when tuning up without PA B+ applied. The HX-50
doesn't even have a grid current mode on the meter, so maybe this is less of a
concern?

Tnx and will keep you informed -- Mike K. AA1UK

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