RadioBanter - View Single Post - Firing up a Hammarlund HX-50 TX

February 23rd 04, 03:38 AM

In article ,
r (Mike Knudsen) writes:

Everything seems to work, except no modulation on SSB or AM -- that is, no
increase in RF out or DC in when I zap the mic center pin with a screwdriver,
with the AF gain turned full up

I got the audio and modulation working, and verified the rig works on SSB and
AM. The problem was a forehead-slapper: when I wnet to feed an audio
generator into the mic lead, I found a dead short to ground. Thinking the
shielded cable from the Amphenol connector to the audio tube had shorted out
(often happens when soldering melts the inner insulation), I lifted the cable's
ground at the tube end. Still shorted.

Then I got suspcious and checked out the mic connector more closely. Turns out
some genius at Amphenol had designed it so that when no mic is screwed onto it,
it shorts to ground! The center contact is on a metal plate that actually
moves in bit to flift the ground when you screw onthe mic cable.

So now I know I have a working HX-50. I'm tepmpted to (temporarily) rewire a
standard 3-terminal phone jack back there, to use my D-104 mic with PTT, and
wire the PTT screw terminal over to the jack. Then I could test the rig on the
air, maybe with the HQ-160 (don't want to risk the HQ-180 on the antenna relay
built into the HX-50 just yet).

Of course before selling the rig I'd put the Amphenol jack back in, right? Or
include it in the package and let the buyer decide?
73, Mike K. AA1UK

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