Re: Oddball Raytheon Subminiature QF-721 tubes

[NT]

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

[Patrick Turner]

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.

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[Arny Krueger[_4_]]

"NT" > wrote in message
...
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.
>

http://townsendtubeworks.com/6088.htm

[Arny Krueger[_4_]]

"Patrick Turner" > wrote in message
...

>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.

The circa-1960s Hawk RADAR sets that I worked with in the Army were loaded
with 100's of subminiature tubes. About 400 per unit. Most of them were
used in applications and with voltages and signals that were usually being
performed with miniature tubes. Construction-wise what internals that could
be seen resembled a minature tube with most of the empty room and spacers
taken out. If memory serves a dual diode was the only type with more than
one function. I'm drawing a blank about dual triodes. The subminature tubes
were rated to be highly rugged (they were also used in missles and artillary
shells) and long-lived - at least 10,000 hours. In the equipment I worked on
they were clipped onto heat sinks that underlaid the swaged-post epoxy
terminal boards that the other parts and wireing were attached to. The
chassis were like 19" long sheet cake pans and mounted as back-to-back
pairs in pull-out drawers. Air was forced in between the chassis. The
chassis were held in place by aircraft-style screw clip fasteners and all
connections were via a single multi-pin connector with both shielded and
unshielded pins and teflon-coated silver-plated fine stranded wiring.

The filament supplies were magnetically-regulated 6.3 volts DC while the B+
was highly regulated 250 or 300 volts. The few socketed tubes were power
tubes including 300A series regulators in the power supplies. Air
temperature inside the equipment boxes was up to 140 degrees.