HW 100 CXR NULL

[Dick KF4NS]

Just finished a couple mods and removing a couple, so decided to 
realign the rig before I box it up. When I got to the CXR NULL, I 
tried to do it with my VTVM but with my old eyes I found that I could 
see things better with the scope.

On the LSB null capacitor, I am reading 0.5V P-P and it was easy to 
adjust. When I got to the USB null pot the trouble started. I was only 
able to get it down to 1.4V P-P and that was after lots of frustration 
due to errratic readings. I have heard about the nightmares concerning 
that pot but never had a problem since I built the rig in '70. I 
cleaned it good with contact cleaner and then added some D5 but it 
still is difficult to adjust and the lowest reading did not change. 
Heath gave no indication of what to consider a satisfactory reading 
other than to look for a comparable reading for USB/LSB.

Any ideas or comments?

By the way, the most recent mod really did inprove the audio. I did 
the balance of the BFO that Mark WBYJKR SK, recommended. Now there is 
no difference in the sound between USB and LSB and the repositioning 
of the filter center frequency makes the sideband signals sound so 
much better. Sure do miss having Mark around since he had a world of 
knowledge about the HW/SB rigs. Hope he is up there teaching some 
angels how to tweak their old heathkits.
73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow! 

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