>I believe the Alpha 77 series were the last to violate NEC but not the
> only company do do so.
As I recall, some of the old Henry amps used chassis ground as a neutral as
well. On the Alpha 70 and 77 series, the fix to the amp is easy and doesn't
even require turning a single cabinet screw. Neutral and ground can be
separated by cutting a jumper on the power cord's Cinch-Jones plug. After
the change, the amp complies with today's NEC.
Of course, the real hassle is in converting one's AC shack wiring from
3-wire (L1-L2-G) to 4-wire (L1-L2-N-G). When I moved to the current QTH, I
ran 4-wire, #10 AWG from the start. Pulling that stuff through the walls is
not a fun process as an electrical re-work project.
Speaking of the chassis-carrying current, I recently modified my Alpha 77Dx
by adding a filament RFC, thus raising the filament return above chassis
ground. I've always detested using the chassis as a high-current-carrying
conductor. For a single 8877, that's 10A of AC current. For the 77Sx,
that's 20A of current through the chassis. For me, another benefit was in
the reduction of filament V as a result of high utility line voltage. It
went from 5.6V before the mod to 5.0V after the mod due to the slight (but
needed) IR drop through the new filament RFC. Arguably, even the newer
Alpha amps that utilize the chassis as a filament return could probably
benefit from a filament choke upgrade.
Paul, W9AC
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