[Hallicrafters] HT-44 Balanced Modulator Observation and Other Musings

[Freeberg, Scott (STP)]

Friday I finally made my first 20 meter SSB contact with the HT-44/SX-117 setup.  I felt a great pride upon announcing that I was using classic Hallicrafters tube equipment.  I quickly noticed that I needed to run the mic gain at 9 to get some normal SSB power out.  TX tunes up FB on CW with full power out, so its not a final tube problem.  I'm guessing that that I'm either running the wrong impedance mic or one of the preamplifer tubes is weak.  

Later I answered a 20 meter AM CQ but the guy came back to someone else.  Yes I used AM :->   The next day, oddly enough I had a carrier on my SSB.  And YES I was in the USB and LSB positions :->>>   Apparently the transmitter loved being on AM so much it wanted to do it all the time :->  Thanks to the early tips on HT-44 balanced modulator issues, I suspected it right away.  I went in and just tweaked the carrier back out.  Now I wonder why on earth would that have changed in one day.... I suppose thats just a sign that the modulator parts need to be replaced.

I noticed some power supply hum from the receiver so I suppose its time to replace the HV caps in the SX-117.  Though as my buddy Chuck W4MIL would tell me, it was time to replace those caps before I even turned it on the first time  :->>>>  When I order those caps, I'll also order replacement electrolytics for the PS-150 power supply as well and just get it over with :->  I did notice that when I was tweaking the balanced modulator, there was enough TX hum to slightly generate a slight bit of power, so its another motivation to recap the power supply.  

I wired up the gorgous black Hallicrafters (Turner) mic and tried it out.  Yuck.  Its all muffled and bassy sounding.  I'm figuring the mic element has aged terribly.  I'm thinking about buying one of those Mouser mic elements that I've been hearing about.  The BA guys have been reporting great success with a $2 or $3 Mouser mic element in their D104's.  

Since I couldn't find an HT-45 Loudenboomer, I moved the SB-220 into the Hallicrafters operating position.  I'm wiring it in now.

I also spent a little time experimenting more with the notch filter.  I would tune in multiple stations on SSB or CW, and try to notch out one or the other stations. Wow, it really does work well!

I just thought I'd share my Hallicrafters adventures with you.

73, Scott WA9WFA
www.qsl.net/wa9wfa
http://wa9wfa.home.att.net