DXing (fwd)

[SCN User]

FWd: help needed bring Hammarlund back to life!

    i                     NorthWest QRP Club                    __________
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---------- Forwarded message ----------
Date: Thu, 17 Apr 1997 08:34:10 -0500 (CDT)
From:rlandman at ix.netcom.com
To: nwqrp at scn.org
Subject: DXing

Hi Brian!

Well, I think I have a find (or a way to kill a lot of time):

Last night I was over at the Voc school (I'm now an advisor to the electronics class)
and the teacher (Paul) wants to clean house a bit.  I spotted a Hammarlund HQ-170A (vacuum tube type rcvr that covers 1.8MHz - 54 MHz) and asked if I could have it and he said, sure so I lugged it home.

I just fired it up this morning (once I found a fuse cap and some knobs).  The dials light up and the S-meter even moves (it has a clock on it to automatically turn it on so you don't miss
your favorite station, hah!).  Plugging in an old set of earphones, all I get is a bit of crackle which moves in sync to the S-meter.  Also turned on my old RF signal generator and dicovered that this thing is not working (no big surprise - that's why it was donated to the school, no doubt).  Have B+ and all tubes seem to have ok filaments (they light up or are warm to the touch).  Interesting item is that two of the tubes in the tuning circuit have their filaments kept on even when the power is off (some kind of stabilization circuit - osc??).

At least no capacitors blew up and I don't see any charred parts or obvious signs of a failed part.  So, I will need a schematic diagram to go any farther.  Wonder if anyone in your Ham
group would have an instruction book I could have a copy of?  Any suggestions as to how to go about finding one?

This should make for some interesting troubleshooting.  I haven't tried to fix a radio in, hmm, let's see, 30+ years?  I need to brush up on my radio theory anyhow (blow out the cobwebs) so
this seems to be a practical way to do it.  I have a ton of old tubes and if it is one of them. hopefully I have what I need.  I think Paul may have a tube checker (and if so I'll try to get that too).  When I retire, I'd like to fix up a few old radios (like the one in the livio\ng room) to fool around with.  Maybe I can help Paul and teach a bit of radio (tubes are easier to understand, I think, than transistors, when you are starting out - Prof Paul Nalin at UNH agrees and wrote a book titles "The Science of Radio" and its based on tubes for that reason (I've got it an have been reading it - antennas are very confusing to me - how radio waves propagate away from the antenna, weird stuff!).

Bob