Oddball Raytheon Subminiature Tubes QF-721
 

In article ,
Scott Dorsey wrote:
Kenneth Scharf wrote:
On 08/13/2011 01:48 PM, Richard Knoppow wrote:

Among other applications sub-miniatures were used in
hearing aids and model aircraft controllers.


Subminiature tubes were developed as bomb fuses for use in mines and
torpedoes.

I think indeed the first subminis that came out of the Raytheon plant
were intended for proximity fuses. Those were designed with very heavy
reinforcement so they could handle heavy acceleration parallel to the
plate, and that same technology made them useful in a lot of other
low-microphonic applications.

Some of the last ones that came out of the plant were spares for the
first and second generation B-52 navigation systems, which used a
von Neumann machine made up of around 250 submini tubes.

In the meantime they went into everything from Army field radios to
weather balloons to condenser microphones.

They were just a hell of a great technology if you ask me.

I think that the first Raytheon subminiatures were from 1938-39 and
made possible electronic amplifiers for hearing aids that could be
worn in a man's suit. Beltone and Sonotone were producing amplifiers
with these tubes that were about the size of a pack of cigarettes in
1940. The proximity fuse tubes were a ruggedized development of an
already-mature product made in quantity for a ready civilian market.

I don't know when Raytheon last made subminiature tubes, but do know
that they were going into new-manufacture missile warhead guidance
electronics until the early-mid 1970's.

Sonotone did have their own line for subminiature tubes, but I don't
know whether that was set up during WWII or afterward. Their first
"transistorized" hearing aid hit the market in 1953, but it was a
hybrid that still used tubes plus one transistor in a cigarette-pack
amplifier.

Hank

Oddball Raytheon Subminiature Tubes QF-721
 

I don't know when Raytheon last made subminiature tubes, but do know
that they were going into new-manufacture missile warhead guidance
electronics until the early-mid 1970's.

Production line shut down in 1983, I think. That factory now only makes
magnetrons and travelling wave tubes.

Sonotone did have their own line for subminiature tubes, but I don't
know whether that was set up during WWII or afterward. Their first
"transistorized" hearing aid hit the market in 1953, but it was a
hybrid that still used tubes plus one transistor in a cigarette-pack
amplifier.

The Japanese made the things too, and there were other companies like Hy-Vac
making them.


BUT... as far as the original poster's tube goes, I got a couple from him
in the mail and it looks to be a pentode with a 5J pinout. My guess without
putting it on the curve tracer is that it is likely to be a CK531DX. I'll
try and test it more carefully this weekend.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Oddball Raytheon Subminiature Tubes QF-721
 

On 12/08/2011 23:29, Robert Seely wrote:
Hello, My apologies for the intrusion. but I have a question that I
am
hoping someone has an answer to. I have never posted to a news
group,
so again, my apologies if this does not meet the standard protocol.

I have a bunch of Raytheon Subminiature tubes that I inherited from
my
Father, who was an electronics bugg (I followed a different path)
that
have code QF-721. In searching the internet I have found a bunch of
identical looking tubes such as one labeled CK6088. I have done lots
of searches on the internet and I cannot find out anything about
these
and am wondering if you know about these, or if you can point me to a
website that might shed some light on these.

I am considering the possibility of donating these to someone but if
I
cannot find out what they are for, I cannot imagine how I can find
who
to donate them to -- perhaps a school or something.

Robert,

I've seen these over here in the UK, although they were made by Mullard
and had type numbers like EF731, 734, etc. I believe they were known for
a while (at least in the UK) as "deaf-aid valves" as they were used in a
body-worn amplifier for a ear-insert hearing aid. I came across them in
a radio-navigation system made back in the early 60s where they were
used for RF and IF stages up to about 3 MHz.

HTH

'BF