In message <005201c0abf2$2e992e40$3025ff3e@oemcomputer>, Paul
<[email protected]> writes

Hi all,

Subject thread is heading back towards my territory!

The silver EF50's were service issue valves - VR91 for the RAF, ARP12 for
the army. I suppose the navy must have had them as well, but I don't recall
the designation....Red ones were the civilian issue.

The EF50 has been described as "the valve that won the war" so ubiquitous
was it and so advanced in performance compared to other valves of the time.
I'm sure I recall my late father saying the H2S set had over 100 of them,
and it was unknown for them all to be working simultaneously!

Might go and dig some out and try a new LF preamp. (need all my 807's for
the PA.....)

I made an RF pre-amp using one in about 1948, tuned to Ally Pally TV
sound. With a dipole mounted on a broomstick poking out of my bedroom
window I received the London TV sound channel loud and clear in south
Wales!

Mike
--
M.J.Powell