HT-33a/b  "HomeBrew"

I acquired this amplifier in the Fall of 2004.  When I first saw the pix I suspected that it was a Hallicrafters HT-33 that had been re-packaged.  It turned out that it was.   The RF deck had been saved intact, but almost all the power supply components were not original Hallicrafters.  The owner had made a very nice cabinet for the RF deck, assembled almost totally with "pop-rivets."  The power supply was on a galvanized sheet metal chassis that was a bit light for the weight of the HV transformer and other components, again assembled with pop-rivets.  A very nicely formed and welded cover had been made of heavy gage perforated stainless steel.  It may have been an HT-33A, and upgraded to an HT-33B.

Pix "as found"

pix after cleanup and rework of the power supply.

The 4 10kohm 50watt dropping resistors for the screen voltage had been located under the chassis, with a fan, but the excessive heat in the enclosed space had driven 2 of the resistors to failure.  New ones were purchased, and they were placed above the chassis, with the fan on a new bracket.  The rectifiers were a string of 11 silicon diodes per leg, with equalizing resistors and capacitors, as was common some 15-20 years ago.  New 2 HV diode modules were purchased from K2AW's "Silicon Alley", and a bracket was fastened to the transformer with 6-32 hardware into tapped holes in the cast iron end bell.  

It is now, in Jan. 2005, operating well on the air,  presently driven by a Hammarlund HX-500 transmitter.

to see the HX-500

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