[Amps] 3-500Z convertion

[Karl-Arne Markström]

It was actually Jan-Erik SM2EKM (the other SM list member with a double first name) that wrote that. 
The 4X500 is very much a FM/TV transmitter tube (valve).
They were extensively used in the first generation European TV transmitters as drivers.

73/

Karl-Arne
SM0AOM

----- Original Message ----- 
From: "Peter Chadwick" <g3rzp at g3rzp.wanadoo.co.uk>
To: "R L Measures" <r at somis.org>; <g3rzp at g3rzp.wanadoo.co.uk>
Cc: <amps at contesting.com>; "Hsu" <Jbenson at sohu.co>
Sent: Tuesday, July 25, 2006 10:59 AM
Subject: Re: [Amps] 3-500Z convertion


> Rich said:
> >no, I thought he said only one of the two tubes was bad.<
> Major confusion here........I thought he needed to replace both of them. From what Karl Arne said, it sounds a bit as if the 4X500 is 4-250/4-400 with a different base and an external anode. That makes them sound attractive, except for the fact that the shape of them is awkward - the anode cooler comes down very close to the glass envelope. I've a vague memory that they were originally meant for use in FM BC tx's, with a copper pipe tank circuit, down which the air was blown, but memory may be playing tricks. However, such a tank circuit would cool them effectively, although you'd need another fan on the bottom for the filament seals. They came out in about 1946/7 time.
> Still sounds like a major mechanical project on a TL922.
> 73
> Peter G3RZP
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