flipper wrote:

In a rather strange turn of events I have been given what the
presenter said was simply a "transmitting tube."

Well, it arrived today and the thing, a planar triode I presume, is
huge. 9.75 inches stem to stern and 4 inch diameter at the plate
heatsink.

The only markings are, on the plate heatsink, "THERMAEL", or
"THERMAIL", or "THEMRACL," or "THERMALL." Hard to tell as the next to
last letter is faded/scratched somewhat, on a red, lightning bolt
framed, triangular background. The 'R' also tails into a lightning
bolt. "5-6" is under it.

Take some pictures and post them at a binaries ng or to those who might
know.

Patrick Turner.



On one of the lower rings there is a small "7647" in the same red as
the above label. And at the bottom, the number "Y6-4479" has been hand
engraved onto it.

Searches don't seem to come up with anything. Does anyone in here have
an idea what it is and where I could get a data sheet on it?

in article , flipper at
wrote on 9/20/05 4:50 AM:

In a rather strange turn of events I have been given what the
presenter said was simply a "transmitting tube."

Well, it arrived today and the thing, a planar triode I presume, is
huge. 9.75 inches stem to stern and 4 inch diameter at the plate
heatsink.

The only markings are, on the plate heatsink, "THERMAEL", or
"THERMAIL", or "THEMRACL," or "THERMALL." Hard to tell as the next to
last letter is faded/scratched somewhat, on a red, lightning bolt
framed, triangular background. The 'R' also tails into a lightning
bolt. "5-6" is under it.

On one of the lower rings there is a small "7647" in the same red as
the above label. And at the bottom, the number "Y6-4479" has been hand
engraved onto it.

Searches don't seem to come up with anything. Does anyone in here have
an idea what it is and where I could get a data sheet on it?


How do you know it is a transmitting tube? Can you prove it beyond doubt?
What evidence do you have to conclude that it is a planar triode? I don't
believe your interpretation of the markings because I cannot see them. Can
you provide photographs of all surfaces of the device? Indeed, is there any
knowledge so certain that no reasonable man can doubt it?

flipper wrote:
In a rather strange turn of events I have been given what the
presenter said was simply a "transmitting tube."

Well, it arrived today and the thing, a planar triode I presume, is
huge. 9.75 inches stem to stern and 4 inch diameter at the plate
heatsink.

The only markings are, on the plate heatsink, "THERMAEL", or
"THERMAIL", or "THEMRACL," or "THERMALL." Hard to tell as the next to
last letter is faded/scratched somewhat, on a red, lightning bolt
framed, triangular background. The 'R' also tails into a lightning
bolt. "5-6" is under it.

On one of the lower rings there is a small "7647" in the same red as
the above label. And at the bottom, the number "Y6-4479" has been hand
engraved onto it.

Searches don't seem to come up with anything. Does anyone in here have
an idea what it is and where I could get a data sheet on it?



It isn't much, but the brand is most likely "Thermall", a (now defunct?)
manufacturer of induction/dielectric heating equipment. I have a glass
triode (looks like a 3-500Z) in my collection with their logo on it.

Bob Weiss N2IXK

Is it perhaps a 7647 planar triode ?

I haven't found one listed in any online guides but I only looked a
short while.

On Tue, 20 Sep 2005 22:38:43 -0500, flipper wrote:

Well, since that's a number on it, and printed, I suspected as much
but I can't find a listing anywhere for a 7647.

It's almost certainly a date code, DOM, or re-manufacture.
47th week of 1976.

Chris Hornbeck

On Wed, 21 Sep 2005 00:16:04 -0500, flipper wrote:

Well, since that's a number on it, and printed, I suspected as much
but I can't find a listing anywhere for a 7647.

It's almost certainly a date code, DOM, or re-manufacture.
47th week of 1976.

That's what I suspected the hand engraved number was. Why would you
suspect the red stamped on number first?

The stampings were done by hand, too. Probably just
exactly like you or I would do it tomorrow morning.

This YYWW format is pretty common, and a likely
first guess, *especially* for such a likely number.


I suppose the red one could be DOM and the engraved one a rebuild.

Sounds good to me.


So you think the "5-6" is the type?

Sorry, no clue. But if neither GE or ARRL lists a
number (like 7647, for example) *that* number seems
less likely. Not at all impossible, just a lot less
likely.

Good fortune,

BTW, what are ya gonna do with *one* forced-air
cooled transmitting tube?

Chris Hornbeck

flipper wrote:


Do you think they actually made them or simply put their logo on them?


Most likely they simply had their logo put on tubes they purchased
elsewhere. The infrastructure they would need to build transmitting
tubes would be more than they needed to build induction heaters! The
tube I have looks EXACTLY like an Eimac 3-500Z, down to the locations of
the internal date codes, number of welds, etc.

Bob Weiss N2IXK

flipper wrote:
On Wed, 21 Sep 2005 04:26:45 GMT, Chris Hornbeck
wrote:


On Tue, 20 Sep 2005 22:38:43 -0500, flipper wrote:


Well, since that's a number on it, and printed, I suspected as much
but I can't find a listing anywhere for a 7647.

It's almost certainly a date code, DOM, or re-manufacture.
47th week of 1976.

Chris Hornbeck


That's what I suspected the hand engraved number was. Why would you
suspect the red stamped on number first?

I suppose the red one could be DOM and the engraved one a rebuild.

So you think the "5-6" is the type?


There is no "7647" listed in any of my transmitting tube manuals, and I
have a pretty extensive colection. Most likely a date code.

The "5-6" may be a type designation, but it would be an "in-house
number" unique to Thermall. Some manufacturers do stuff like this to
prevent the user from buying replacement parts from other, cheaper sources.

Posting a picture might help us identify what you have....

Bob Weiss N2IXK

Flip,

I quoted your post on a neat forum called Big Valve Amps
http://groups.yahoo.com/group/bigvalveamplifiers/ . I was directed there
years ago by a post here at R.A.T.

These bottleheads have an affinity for finding oodles of huge tubes and
building stuff with them. Maybe they'll have a better idea of what you've
got.

I'll repost anything they suggest.



"flipper" wrote in message
...
In a rather strange turn of events I have been given what the
presenter said was simply a "transmitting tube."