[Hallicrafters] HT-33A amp followed me home

[Mark Shaum]

From: "Fern Rivard" <crc at cyberlink.bc.ca>


>     A Hallicrafters HT-33A hf amplifier with the Penta PL-172A final
> followed me home in the past few days. Does anyone have any mods that
> were pertinent to those amps that I should be made aware of? Also what
> is the approximate value of such an amplifier? It is in pretty good
> cosmetic condition except for a broken glass on the front of the
> multimeter. Any useful info on replacing that glass would be most
> helpfull.
>     Thanks and 73 from Fern

Fern, there was one engineering change I am aware of that occured during
the lifetime of the 33A.  The original screen voltage was upped by using
the
six tube series-parallel combo of VR tubes as used in the 33B compared
to the four tube original version.  My 33A already had this retrofit
done, although rather sloppy.  Also the original 20A HV switch/circuit
breaker was upped to a 22A version at some point in time.

I found that with a tad of positive voltage on the suppressor grid, the
33A easily put 1500 watts out CW without apparent strain.  I didn't
leave it in this form, as even with a spare PL172 I don't want to lose
one.

One thing I plan to do this winter is to remove the HV iron and mount it
externally.  The 33A is just too darn heavy to move it around my shack
otherwise.

Mark K9TR