If you seriously look at a 1625 compared to an 807 the tubes mount far more
securely in the sockets. Since the tubes were utilized in aircraft I'm
pretty sure the end result was far more stability in the socket. When I
removed the 1625's from my ARC-5 I remember they were really in there.
I would think a tube that large with an OCTAL type phenolic socket would
break the locating pin in airborne applications.
I'm sure we could ask the designer of the 1625 if it was 1950... Whoops
sorry to late. BUZZZZZ Dialtone.
From: firstname.lastname@example.org [mailto:email@example.com] On
Behalf Of Peter Chadwick
Sent: Friday, July 27, 2007 4:20 AM
Subject: Re: [Amps] Gassy Tubes/Technology Museum looking for artifacts
>Wild guess: to prevent plugging a 6.3v filament tube in a 12.6v socket?
Maybe 807's were also used in other applications in that era.<
It seems a bit illogical, because there were 6 and 12 volt octal tubes with
the same base connections - 6K7, 12K7, 6SG7, 12SG7 etc. Further back, there
were 2.5 volt and 6.3 volt tubes on the same UX base - 2B7 and 6B7 come to
mind. So why go to the bother for 1625s, when they needed more metal for the
two extra pins? And the quantity of 1625s made meant that must have been a
fair weight of brass for those two extra pins.
807s were around pre war, and there was one of the early RAF VHF
transmitters used something called an 8018, which my father told me was an
807 selected for more output at 120MHz - he actually instructed on that
equipment when he was in the RAF. He said it was awful speech quality, using
the device as a sort of linear with low level grid modulation on the
preceding frequency multiplier, and running grid current in the 8018.
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