>
>Hi all,
>
>I have some items that may be of interest to high power amplifier
>builders.
>1. Unused Econco rebuilt 4CX5000A.
>2. Unknown condition 4CX5000A (might work, or could be rebuilt).
>3. Eimac SK300 socket in very good condition.
>4. Electro 7.5v 75A filament transformer with 208/230V +/- 5 &
> 10% primary taps. Fil trans has center tap.
>
>This tube can be run in grounded grid, where 400 watts of drive
>provides 10kw out, or in AB1 with screen voltage for reduced drive
>applications.
Other builders of g-g 4cx5000a amps typically use a SB-220 to drive the
cathode. 150w will drive the grid in AB1.
>SK300 socket includes screen bypass caps.
>
I bought such a socket at a surplus store. This socket is for audio
amplifier service, not RF service. In order to convert the AF socket for
RF use, I purchased the required parts from Eimac and removed the
doorknob caps. For stable RF amplifier service, the screen collet must
be grounded in eight places with c.10mm Cu ribbon. A diag. of the
grounded screen, grid driven configuration is on my Web site. While I
had the SK300 socket disassembled, I used a fine tooth coping saw to trim
excess metal from the screen and grid collets - thereby reducing back
pressure to cooling air, like an SK300A socket.
- later, Jack
Rich. Measures.,www.vcnet.com/measures, 805.386.3734
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