At the risk of starting a raging philosophical war, I am looking for
opinions on how to best manage wiring between an outboard HV supply and an
RF amp deck.
Here's the project:
An old Alpha 77D is being used as the foundation of a quasi-homebrew amp.
The plan is to upgrade the PS and move the HV transformer and oil cap out of
the RF cabinet and into its own enclosure -- similar to what K2VCO and W8ZR
have done. I am doing this for two reasons: (1) I can no longer manage the
weight of a 77Dx amp by myself. It already takes a meditation exercise to
move my older Alpha amps from the ground and onto the desk; and (2) Ep will
be slightly elevated with better regulation under full load. A new 2.0A CCS
Dahl plate transformer will be purchased from Hammond. The existing
25uF/4KV oil cap gets upgraded to 35 uF/5KV. A dedicated filament
transformer will be mounted in the RF deck area once occupied by the old
Hypersil HV/Filament transformer.
A new PS cabinet is being fabricated and will house the HV transformer,
filter cap, diode stack, and perhaps a bleeder pair. I would like to use a
SHV connector for HV, but after reading the AMPS archives, I'm seeing widely
varying opinions on how to best manage B- I've seen everything from just
running it like a control conductor at one extreme to using a dedicated SHV
connector and treating it like HV at the other extreme. A 2-3 diode string
will be used between B- and the chassis as it is now.
The new amp is getting a complete facelift with a new engraved front panel,
round 250-degree meters, and a vacuum variable cap will be used for loading.
Dedicated metering for Ep, Ip, Ig, and filament voltage. The Pi-L section
will be be upgraded but remain mostly the same. Bias is redesigned using a
3-stage bias system with the entire bias and T/R function being
software-controlled from my S-QSK board. A matching PEP analog wattmeter
with Bird ThruLine section has been designed and can be used either above
the amp or remoted to a small desktop enclosure.
http://72.52.250.47/images/77D_Panel.pdf
As I move forward with this project, opinions regarding current trends in
SHV/B- distribution are very welcome. Tnx!
Paul, W9AC
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