Hammarlund HX-500 Transmitter

November, 2004

11/20/04  -  It's dirty inside and out, chassis is chromed so it will clean up very nicely.  Front panel has some paint scrapes, but other than that & some dirt, is OK.  It's HEAVY. 

The factory recommended power supply changes have been made, but I think it doesn't have the updated power transformer.  SS rectifiers have been soldered under the rectifier sockets, some pins have been changed, so tubes can't be plugged back in without re-doing.  The other mods in factory bulletins don't appear to have been made.

After inspection AC voltage was brought up slowly on a variac, and appears to be working properly, 100+w out on 80 thru 20 meters, ~70w out on 15 & 10 meters.  Audio, and sideband rejection seems good by monitoring, need pair it up with a receiver and try it out on the air.

After cleanup it looks much better inside:

   I did put it on the air the week of 11/22/04 and had 2 or 3 short QSO's, but it wasn't a good situation for asking about quality, etc.  On the Vintage Sideband net on sun., Lynn, K5LYN, said it was sounding good, but there was QRM, and I was only getting about 80 watts out, so the signal wasn't strong enough in Texas for a good "inspection."  

   After the net closed, I heard a pop, and wasn't sure if it was in the rcvr audio (Drake 2-B) or in the xmtr.  Then a few minutes later I smelled something hot.  Got into it, 2 dropping resistors in the 300v line to a mixer screen had burned thru.  Turned out a 0.02 disc ceramic bypass at the screen had shorted, it measured 0.47 ohm.  So, disc ceramics can fail.  I got that fixed 11/29 PM, and also  performed a thorough RF alignment,  and could get over 100w out on all bands.
    I'm also ckg out, working on, diagramming, & understanding, a repackaged  HT-33A amp, with separate HB p.s..  It wasn't quite ready for the net on Sun., hopefully next wk. Didn't want to hurry while messin with 2700vdc.  The HV xfmr the guy used in it must weigh close to 100#.

To see the HT-33 

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