On Jan 4, 5:40*am, lkdubb wrote:
I recently purchased a Hammarlund HQ110A and I cannot get it to operate.
It powers up, the lights and meters seem to function properly, but I
cannot get any reception - just white noise. I do not have external
speakers, so I use headphones....I do not have a proper antenna, so I'm
just using a length of wire....since this is all new to me, I'm not sure
of how to set the various controls on the unit (pitch, sensitivity, AVC.
LIM, audio gain, freq, selectivity, multiplier).
Can anyone offer me some advice?
Also, how hard is it to find parts and to get repairs on these units?
Thanks.

It is actually easier to repair old vacuum tube electronics than it is
to repair a modern IC based radio that is out of production by a few
years. There's plenty of new old stock (NOS, "new" in the box yet 50
or 60 years old) tubes still out there. But tubes don't go bad just
sitting there, so the tubes in your radio are probably OK. More than
likely, the problem is in dirty switch contacts, or resistors or
capacitors that have gone bad. One can find new stock replacements
that might not look much like the old ones, but electrically are far
better and more reliable.

You will need a voltmeter (preferably a vacuum tube voltmeter, but a
modern digital multimeter will work, especially if it has a bar-
display mode which will be useful for aligning the IF coils an
transformers). A signal generator that can go up to at least 30 MHz is
also a big plus, since it will help a great deal in aligning the set
(more than likely, it has drifted out of alignment, re-aligning it
will restore it to like-new selectivity and sensitivity).

It's best to get a service manual for the set, particularly if you
haven't done this sort of thing before. Then you can just follow the
troubleshooting and aligning instructions therein.

More tips on fixing old radios can be found at: http://www.antiqueradio.org/howfix.htm

--
David Barts
Portland, OR

PS - Be aware that vacuum tubes require and use significantly higher
voltages than semiconductors. You will have to take precautions to
avoid getting zapped. You can't be casual around powered-on vacuum
tube electronics like you can around low-voltage semiconductor
circuits.

--
David Barts
Portland, OR