[Boatanchors] Solid-Stating a Johnson Valiant Power Supply

[Michael D. Harmon]

I recently became the proud owner of a very nice Johnson Valiant 
transmitter.  I've done the normal cleanup and tube checking stuff, and 
the next step will be capacitor replacement.  The transmitter has had 
the 866A rectifiers replaced by a pair of RCA CR-105 diodes epoxied into 
a couple of 4-pin tube bases.  Since the old HV rectifier tubes are 
already gone (and I really don't want all that mercury around anyway), 
I'm thinking about solid-stating the remaining power supplies as well.

I'm sort of ambivalent about this project.  I've always been hesitant 
about making major mods to a piece of vintage gear, but I'm planning to 
actually use the Valiant, so preserving its life as long as possible is 
more important to me than maintaining its "vintage vibe".

I've heard comments from both sides - I've been told to solid-state all 
the power supplies, and I've been told to leave the power supplies 
alone.  I know converting the power supplies will bring up the B++, but 
I plan to recap the entire transmitter anyway.  I plan to use poly film 
630V caps for all the tubular replacements, and 450V caps for the 
electrolytic replacements.

By eliminating the filament wiring, I should relieve the LV transformer 
of some filament current, as well as the HV running on the filament 
leads.  I should also eliminate some heat in the cabinet.

Other than the caps, What else can I damage by increasing the B++?   Are 
there other areas I should be careful of?  I don't anticipate any 
problems with the chokes or the mica and ceramic caps, but there may be 
other things I'm not aware of which could jump up and bite me!

I would really appreciate any suggestions, tips, warnings or helpful 
comments from anyone who has done the conversion to solid state.  Oh, 
and BTW, I'm not all that sure about those CR-105 diodes which were used 
to replace the 866A's.  I found them listed in a 1963 Allied Industrial 
catalog for $22.40 each, but there's no other documentation on them. 
They say 5000 PIV, but they have to be at least 50 years old.  I'm a 
little dubious about how well they would hold up if I start using the 
Valiant a lot.  Should I replace them with some commercial 866A 
replacement diode stacks or possibly a few 1N5408's with 470K resistors 
and .01 uF caps across each diode?

Thanks!
Mike, WB0LDJ
mharmon at att dot net