On Aug 13, 4:12*pm, NT wrote:
On Aug 12, 11:13*pm, 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.
Schools arent normally interested in tubes. Generally only museums or
collectors would be.
NT
Schools sure are not interested in tubes and one reason might be
because of the high voltages involved and litigious parents who have a
habit of suing schools for killing kids by electrocution during
science classes, and besides, tubes are like horse and buggy
technology, nice ride, but slow, and well out of date, and there's a
1,001 other more important things to teach kids about.
If you can't find data at such tube data sites like
http://tdsl.duncanamps.com/tubesearch.php
then to find out what's inside any tube you just have to experiment to
find out. Not so easy, but the principles of operation of the sub-mini
tubes is the same as most others, you need a heater voltage just
right, anode to cathode voltage just right, grid and other electrode
voltages just right, and see what you get using meters and
oscilloscope.
Some sub-minies were used for hearing aid apps, so B+ was not high,
nor was filament voltage and current. But principles are the same.
Not many people I know bother trying to use sub-minies for anything
because most apps these days use octal, mini 9 pin or 7 pin tubes and
plugs and sockets. Some ppl are say the best audio preamp might be
made using a sub-mini with soldered in tube leads. I can't argue with
them because I've never heard a preamp using sub-minies but I have an
order from a guy wanting me to build such an amp. If you search around
you'll find quite a few type numbers were made, but only very few have
been given special status for hi-fi amps, and those tend to be high gm
twin triodes. If you donate the truckload of sub-minies you have to Mr
X who says he might like to use them it is most likely they will lurk
on Mr X's garage shelf until he dies and never get used, and then be
chucked out to the tip within 10 years by his relatives who don't care
about the useless junk.
Patrick Turner.