[Boatanchors] Diode replacements for 866 tubes, ratings needed ?

[Rob Atkinson]

You have to be careful making changes to a power supply designed with a
full wave rectifier and center tap secondary.  The old iron especially is
not made to have the CT floated above ground with the entire secondary
always working with a full wave bridge rectifier.   Some plate supply
transformers like the UTC CG series around 1960 and later could be used
with CT grounded or floating above ground.  I'd bet Heath being cheap, used
a transformer made only for the stock power supply design.   There are hams
who not knowing any better fried old power supply iron trying to double the
secondary voltage.   I almost did the same thing with a big old Thordarson
transformer (it is an easy mistake to make if you have not been warned
about it).

 73

Rob
K5UJ

>> If you eliminate the choke that would solve those
> >> high spike problems but then the transformer would
> >> be putting out too much voltage for the 811A's.
>
> I was considering doing that, and converting the amp to use only 572Bs at
> more nearly their rated power than is normally done in 811A amps in which
> people use 572Bs.  If I could get some decent 572Bs I might have done that,
> but those don't seem to be on the horizon.  At least I can still get some
> NOS Cetron 811A tubes, for now at least.
>
> There's plenty of room in there to just convert the thing to use a single
> 3-500, and I haven't yet completely rejected that notion.  I need another
> 811A/572B amp like I need a hole in the head.
>