To add one more opinion, I also feel that the Heath SB220 is a
classic, simple yet elegant design, which is timeless. While the
green two tone cabinet reflects last century ergonomics, the circuit
is quite workable. With the mods available to improve the input
tuning Q (for solid state drivers), inrush limiting or step start on
the HV transformer, the better bleeder resistors, better rectifiers,
a standby switch, and getting rid of that open frame relay for
antenna switching, it can do the exact same job as a modern
amplifier, and maybe better.
It might be compared to Dynaco stereo amplifiers, as they were also
classic with Davis Hafler's engineering, from transformers to the
overall circuit topology. They, too, have be revived for 30 years
with many modifications and improvements. People don't seem to toss
them out (ditto for SB220) but just carry them forward with
improvements and tweaks that make them even better.
My hat is off to the hams at former Heath company for such a piece.
John
K5PRO
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