[Heathkit] Power Transformer Ratings

[Michael D. Harmon]

Hi Andrew,

I don't have the exact specs for the transformer - most of the time 
Heathkit had their transformers custom made for them, so you probably 
won't find an exact match from Stancor, Triad, UTC, etc.

I can tell you that the same transformer is used in both the SB-400 and 
SB-401 SSB transmitters.  I looked at the HW-16 schematic and added up 
the filament currents.  The 6.3V winding supplies 5.25A to the HW-16 
filaments, so it's good for 5-6A.  The bias winding supplies around 
-130V when used with a half-wave rectifier.  The B+ winding supplies 
700V to the PA, plus the B+ voltage to all the other tubes.  The PA 
draws around 220mA when loaded up, plus probably another 75-100mA for 
the other tubes in the unit.  I's guess that the transformer can provide 
700V at 250-300mA when used with a voltage doubler arrangement.  If you 
are building a home-brew transmitter, you should be able to get enough 
out of the transformer to run 75-100 watts.  Just bear in mind that CW 
and SSB service is ICAS, NOT CCS!  Don't try to use the transformer at 
these ratings in AM, FM or RTTY service!

Hope this helps.
Mike, WB0LDJ