[Boatanchors] More RE Western Electric 407A and 408A tubes.

[Norman Hairston]

More input re tubes 407A & 408A. Some input on 416B which I felt were 
more desired by Hams from AE4Q.


Here’s what I remember  about the 407A. It, I believe was used as an 
amplifier, actually two,
because I remember them going into an “N’' Carrier system. So, I don’t 
think they would do much for
VHF or UHF.
And here is what I think I remember about the 408A. Seem that tube was a 
pentode and was similar to
the old commercial 6AK5, also a pentode which, I believe, was used back 
in the days of the Old Williamson
Audio Amplifiers and was being built by audiophiles. Heathkit, Allied, 
Lafayette also had it in Kit form.
The 408A was desired to use as a preamp because of it’s audio response 
and  it’s ability not to be as microphonic.
I once built one but didn’t ever use a 408A All this happened even 
before Stereo, and certainly before anything
solid state, with the possible case of rectifiers.
The 416B was used in the TD-2 Microwave System....three in each 
direction in the repeater bay and another in each
Microwave Generator. Originally there was a 416A but apparently didn’t 
live up to expectations because they didn’t
last long in service and had to be replaced frequently. These 416 tubes 
were gold plated so were expensive.
Now, the 417A tube may be the one some are thinking of. It was the 
driver, I believe, in the Microwave generatore
and was the typical glass 9-pin tube.
Sounds like an interesting discussion you have going there!

73,
Jack


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