From: Chuck Simmons
Organization: You jest.
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Subject: Re: Digital divide by ten, 1949 style
References: <3D84D4B3.50B511EF@webaccess.net> <3D850A3C.31381AD5@webaccess.net> <3D852DB5.2AEB8909@webaccess.net>
Date: Mon, 16 Sep 2002 05:07:43 GMT
NNTP-Posting-Date: Sun, 15 Sep 2002 22:07:43 PDT
"Geoffrey G. Rochat" wrote:
> >5 volts hung on until the end in rectifiers. Correct me if I suffer
> >poor memory but didn't all of the 866, 872 and 575 tubes have 5 volt
> >filaments? These, of course were in power applications.
> No, 866, 866A, 866AX and 866 Jr. tubes were hefty half-wave mercury
> vapor rectifiers with 2.5V filaments. The 866B had a 5V filament, as
> did the 872. I don't know about the 575. 5V filaments were usually
> found in garden-variety full-wave rectifiers such as the 5BC3, 5R4, 5U4
> and 5Y3, although 6.3V filament full-wave rectifier tubes such as the
> 6AX5 and 6X4 were not uncommon. Most 6.3V rectifiers, however, were
> half-wave horizontal damper tubes such as the 6CL3. And, of course, the
> 35W4 found in many AA5 radios had a 35V filament with a filament tap
> intended to drive a #47 incandescent pilot lamp.
The 866 was not really hefty. Rather small as I remember and used in low
power stuff. The 872 was fairly hefty but the 575 was definitely hefty.
It looked like an 872 on steroids. If you needed much more than 575s,
you thought about using ignitrons instead. The 575 could replace an 872
if the filament transformer did not object. The 575 was in some Collins
gear (40 units or so in one building) I worked on that had a 5,000 volt
12 amp power supply (6 575s in a 3 phase Y). There was some other gear
that I hated that used the 575 in a 12,000 volt 5 amp supply. That was
the gear that tended to catch fire. Major PIA cleaning up after a fire.
Usually happened about once a month. It was hard to stock parts for that
because the fires broke out in different places. I had to cannibalize
sometimes and others see if the Navy had the parts. I always arranged
Navy scavenger trips for lunch time because the Navy mess was better
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org