Hi,
This is a slight aside from the HF socket application, but:
In 1983, I worked with the Eimac engineers, while at Broadcast Electronics,
Inc, on an improvement in the SK300A series sockets, for the 4CX5000A or
the 4CX3500A. I cannot be sure of this part number right now, but they
created the SK350/355 series I think, based on our design.There is a
similar socket for the 4CX20,000A/8990 tetrode, and the intermediate
4CX7500A and 4CX12,000A tetrodes. Since we were using them at 100 Mhz, the
SK300A was totally inadequate due to the open spaces and the high
inductance, esp in the filament and screen bypassing. It was not DC
grounded screen, but RF grounded (well, through straps for
self-neutralization at 100 Mhz and plates insulated with Kapton film for
bypass caps). The newer sockets had a series of holes for airflow, which we
determined were not too detrimental for VHF operation - nothing like the
big open areas in the 300A. The filament connections were bypassed with
integral Pyralux (copper laminated Kapton polyimide film) capacitors
sandwiched between the layers. Additional doorknobs (57 series) could be
added for lower frequency bypassing.
Pyralux and Kapton are E. I. Dupont de Nemours trademarks
73
John
K5PRO
To: <amps@contesting.com>
>Date: Sat, 5 Dec 1998 13:13:02 -0800
>From: Rich Measures <measures@vc.net>
>Subject: Re: [AMPS] FS: 4CX5000A, socket, fil trans
>
>>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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