Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!seismo!gatech!hao!boulder!sunybcs!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: Old-fart electronics quiz (long)
Message-ID: <1902@kitty.UUCP>
Date: Sun, 2-Aug-87 16:09:38 EDT
Article-I.D.: kitty.1902
Posted: Sun Aug  2 16:09:38 1987
Date-Received: Sun, 2-Aug-87 21:48:44 EDT
References: <19929@ucbvax.BERKELEY.EDU> <1901@kitty.UUCP> <19930@ucbvax.BERKELEY.EDU>
Distribution: na
Organization: Recognition Research Corp., Clarence, NY
Lines: 63
Summary: More nostalgic ramblings...

In article <19930@ucbvax.BERKELEY.EDU>, max@zion.berkeley.edu (Max Hauser) writes:
> >	Don't forget the ignitron, skiatron, and carcinotron (probably
> >the most unusual name for a vacuum tube)...
> 
> I omitted the ignitron on purpose, since it is not all that archaic
> (it's still heavily used, in power work), but I have never
> heard of the others! I did warn that it was mostly a solid-state quiz.

	The skiatron was an interesting type of CRT which was developed
during WW II for projection of radar displays.  I believe it was subsequently
used for early projection television applications.
	What is so interesting about the skiatron is that it is a DARK trace
tube; the excited area appears as dark magenta against a white background.
In practice, bright light from a mercury arc lamp is focused against the
front of the tube through a hole in the center of a spherical mirror.  The
light from the surface image is reflected by the spherical mirror through
a Schmidt correcting plate onto a front-surface mirror, and then to a
ground-glass image plane.  The skiatron was electromagnetically deflected.
	The carcinotron was the first name given to the BWO (Backward Wave
Oscillator) tube.  I believe "carcinotron" may have started out as a
tradename, but I am not certain.  It certainly is a bizarre name for a
microwave oscillator tube!  Perhaps someone realized that extensive
exposure to its output could cause carcinoma :-).
	BWO's are interesting microwave oscillators since they can be
designed to provide output frequencies as high as 500 GHz - that's a
pretty short wavelength!  BWO's also have an unusually great electrical
tuning range - on the order of 2:1.  BWO's also ain't cheap; I have an
H-P (i.e., High-Priced :-) ) microwave sweep oscillator in my lab with a
sick BWO, and H-P wants a mere $ 4K for a replacement BWO...

> One more thing -- some people collect old radios; I collect old op 
> amps. I have mint Philbrick K2 series amps going back to the
> mid-1950s, with Airpax choppers and 12AX7s. Sometimes I give a talk
> on op-amp evolution to EECS undergrads. I use FETs in the tube 
> schematics for clarity, of course, but you should see the eyes 
> pop at the sight of +- 300V DC power rails.

	There were also some unusual "chopper" circuits which used neon
lamps shining against CdS photoresistive cells to provide a non-mechanical
means of commutation.
	Until the instrument world became truly comfortable with solid-state
electronics, there were some strange hybrid amplifiers which used various
combinations of tubes, transistors and choppers in the same circuit.  One
of the most complex and difficult to understand/troubleshoot circuits I have
ever seen was used by Cary Instruments in their Model 14 spectrophotometer;
not only did they combine vacuum tubes, nuvistors, and transistors in the
same circuit, but some of the transistors were FET's!  I once spent 4 solid
days trying to repair one of these gadgets, only to discover that the
problem was an open 100 megohm resistor in a nuvistor preamp; who would ever
believe that a 100 megohm resistor would be open?
	And then there was Beckman Instruments, who used solid-state
amplifiers with electromagnetic choppers in their Model R Dynagraph instrument
recorders and systems.  Except that 60 Hz choppers weren't good enough;
they used 400 Hz choppers, and even provided a solid-state 400 Hz power
supply just to provide excitation current for the choppers!
	One thing that never seemed to really catch on (except in the
telephone industry) was the use of "Fetrons", which were solid-state
pin-for-pin replacements for vacuum tubes.  Fetrons primarily used FET's.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
<>  UUCP:  {allegra|ames|boulder|decvax|rocksanne|watmath}!sunybcs!kitty!larry
<>  VOICE: 716/688-1231        {hplabs|ihnp4|mtune|seismo|utzoo}!/
<>  FAX:   716/741-9635 {G1,G2,G3 modes}    "Have you hugged your cat today?"