A number of years ago I made a good living fixing Alpha 77's (dx) and
Signal One's. The transformer in the Alpha is seriously underrated for two
tubes. Good enough for the casual operator but I can guarantee it wouldn't
make
it through a contest. The high power mod was to install a Peter Dahl
transformer, replace the HV diodes to larger voltage and current ratings and
replace the vacuum output relay to a RJ2 Jennings. As far as i am concerned
the amp is junk.
I note the complaints about the DC voltage filter choke in the Henry. At
least the Henry has one and the HV regulation is much, much better than in
the Alpha. The resonating capacitor in the original Henry 5K, 3K ultra and
8K ultra was changed to a .2 mfd and that cured the humming problem.
If I remember correctly the original question was the choice between the
Henry 5K and the Alpha 77DX. The Henry is, by far the better ampflier.
Larry
N7DD
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