[RFI] Thought you'd like to see this.....

[Leonard Halvorsen]

**Dale - I'm getting an E-mail Undeliverable error from my last reply to
you.**


It's an S-94,000E.
94 KW Plate Dissipation.
Originally made by RCA, before they sold that division to Burle.
It's a Tetrode.

There is a fiberglas (more or less) "helmet" that fits over that ceramic
part up top, and bolts down to the mounting plate on the bottom. There is a
rubber boot that goes over the cylinder on top and seals to the helmet.
Then the volume between the helmet & the Ceramic Body is filled with about
10 PSI of SF6 for voltage standoff. The SF6 is circulated and cooled a
little during operation.

The pump that circulates the SF6 had bad seals (it looks a little like a
Wankel engine inside) and we got a little too much oil in the helmet. Some
of it must have been a little dirty. You can't see it from the picture, but
there was "tracking" along the ceramic from bottom to top, probably along a
drip of dirty oil. It just kept banging away, and got worse & worse until
we noticed it during operations. The seal along the ceramic/baseplate
finally gave up, and the vacuum was compromised.

The filament runs at 3 Volts (Nominal) @ 4000 Amps (Nominal).
Normal plate voltage (these days) is about 100 KV, and about 50 or so amps.

See Attached.

The tube provides self-regulated HV (feedback loop in the grid circuit) to
the particle beam gun for the Accel Field.

Darn thing oscillates at 400 MC. Physical cavity size inside. Probably the
Screen-to-Cath.
It just can't be swamped out.
We have to reduce the screen voltage and crash the gain to get rid of it.
So, we have to drive the grid a little harder.

My old job over in the other building had the neat RF Tubes. VoA
Transmitter hardware. Eimac X2170's & X2159's. Later, 8874's.

Leo H.


Just WHAT tube am I seeing?  Was the damage from a voltage flash-over or
> from a lightning hit?  Very interesting.  TNX.
>
> 73, Dale
> WA9ENA
>