Here, the pair of 60 uf (at 5 kv) oil caps are mounted. Caps will be wired
in series, and 4 x 100k bleeders used. Center junction of resistors is
wired to center junction of the series caps. Each oil cap is isolated from
each other..and chassis. This ensures each oil cap has the same V drop
across it. 6.5 kv unload B+, so 3250 v across each of the 5 kv rated caps.
3 x contactors used in total, with contacts in parallel. The 'small' 0-270
vac @ 5 amp variac will be used to control the fil V. 2 x 7.5 vac @ 50
amp fil xfmrs are wired in parallel..to handle the tubes 7.0 vac @ 79 amp
CCS requirement. The variac will get it's own right angle drive, so the
fil V adjustment can be done on the rear apron.
The big EBM-Papst blower will hang off the top lid of the B+ supply..and
will provide 330 cfm @ .9" pressure for the tube.(tube requires 204 cfm @
just .4" pressure, but by using the bigger blower, the CCS anode diss is
increased by 20% to
7.2 kw. This is with a 40 deg C (104 F) ambient intake air temp. With a
more normal 20-25 C (68-75 F) intake air temp, CCS anode diss is further
increased to 8 kw CCS. It's an easy tube to cool, due to it's small
ceramic..'stem' (identical to a 3CX-3000A7)...and large diameter anode
fins, esp on the underside of the fins.
2 x holes with mating finger guards on side of B+ supply, allow for the air
intake to the blower. The 330 cfm room air will also cool all the
components, like plate and fil xfmr's, bleeders etc.
A custom gasket will be used between top lid of B+ supply...and bottom
lid of the smaller RF deck box, that will sit on top of the B+ supply.
That's how the compressed air gets to the cathode plenum..then up through
the anode fins..and exhausted out the custom, screened portion of the top
lid of RF deck.
It will all come together in the next 1-3 days. Scott has a bunch of
SB-220's and Various Ameritron amps to fix, so has severe time constraints
as is.
https://www.youtube.com/watch?v=98e93-CIN7c
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