On 25 Feb 2004 12:31:47 -0800, (harry) wrote:

Hi Folks:
A guy at work bought his old guitar amp to get looked at. The
tech said he needed new tubes. (probably really doesn't). However, I
needed to bring in my 833A and said he needed 2 tubes like this!! He
was hysterical!
The tech and I got talking about BIG glass tubes. I was wondering if
anyone knows of a bigger glass tube than 833a , 852 , 861, 4-1000a
etc.

I don't have a photo of it, but I had a 6C21 on 80, 40, and 20. Twas a
bear to neutralize. It looked like a 250 TH on steroids and was about
16 to 18 inches tall.

OTOH, there are many tubes in the multi KW range that are Huge. I've
seen pictures of "walk in" tubes that had an air lock.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Thanks!
Harry

On Wed, 25 Feb 2004 23:41:36 GMT, "Frank Dresser"
wrote:


"harry" wrote in message
om...
Hi Folks:
A guy at work bought his old guitar amp to get looked at. The
tech said he needed new tubes. (probably really doesn't). However, I
needed to bring in my 833A and said he needed 2 tubes like this!! He
was hysterical!
The tech and I got talking about BIG glass tubes. I was wondering if
anyone knows of a bigger glass tube than 833a , 852 , 861, 4-1000a
etc.
Thanks!
Harry

These are pretty big. They're described as 5 feet tall. They're from
Powel Crosley's 500 kw WLW transmitter:

http://hawkins.pair.com/wlw/wlw3.jpg

This is from:

http://hawkins.pair.com/wlw.shtml

Good Gawd, but that is a terrible page to try to read after they load
the background!

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Frank Dresser

Roger Halstead wrote:

OTOH, there are many tubes in the multi KW range that are Huge. I've
seen pictures of "walk in" tubes that had an air lock.

If you ever find those pics, _PLEASE_ scan them and put them up on a
website somewhere, or mail the scanned images to me so that I can put
them on mine.

--
Mike Andrews

Tired old sysadmin

On Sun, 29 Feb 2004 05:22:45 +0000 (UTC), (Mike
Andrews) wrote:

Roger Halstead wrote:

OTOH, there are many tubes in the multi KW range that are Huge. I've
seen pictures of "walk in" tubes that had an air lock.

If you ever find those pics, _PLEASE_ scan them and put them up on a
website somewhere, or mail the scanned images to me so that I can put
them on mine.

"I believe" it was the old VOA station. "It seems" like there was a
story on it wayyyy back in QST. Maybe in the 60s or 70s.
OTOH it could have been one of the very high powered VLF stations. At
least those are a couple of good places to start.

I remember the photo, but it's been a long time.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

In article , Roger Halstead
writes:

OTOH, there are many tubes in the multi KW range that are Huge. I've
seen pictures of "walk in" tubes that had an air lock.

"I believe" it was the old VOA station. "It seems" like there was a
story on it wayyyy back in QST. Maybe in the 60s or 70s.
OTOH it could have been one of the very high powered VLF stations. At
least those are a couple of good places to start.

Most likely you are remembering the plate coil and capacitor output network of
one of the old Navy VLF stations. I remember photos of a big room full of the
inductor and some capacitors that looked like they'd hopped off telephone
poles. The room had copper plated walls and an interlock on the door to cut
the juice if someone opened it.

I doubt there were ever walk-in tubes. The vacuum required for any kindof tube
life is so "hard" and pure that you wouldn't be able to pump out a whole room
to that purity. Though maybe with a really big "getter" ... Mike K.



Oscar loves trash, but hates Spam! Delete him to reply to me.

Mike Knudsen wrote:

I doubt there were ever walk-in tubes. The vacuum required for any kindof tube
life is so "hard" and pure that you wouldn't be able to pump out a whole room
to that purity. Though maybe with a really big "getter" ... Mike K.

I have this image of someone walking in through the airlock with a
_big_ container of cesium or strontium, to be used as a getter, and
hooking it up to a pair of terminals on the inside of the tube once
it has been baked and pumped down for a while.

I also have this image of an enormous induction heater, with coils
completely surrounding the tube, forepumps the size of modern fanjet
engines, and diffusion pumps slinging kiloliters of oil per second.

Somehow, I think it's just not viable.

--
I just overheard someone referring to Solaris 2.6 as a "virgin
operating system". With a straight face, no less. In one sense, I can
see it. The one whereby it knows what it wants to do, it's just not
entirely sure how... -- Carl Jacobs

In article ,
Mike Andrews wrote:
Mike Knudsen wrote:

I doubt there were ever walk-in tubes. The vacuum required for any kindof tube
life is so "hard" and pure that you wouldn't be able to pump out a whole room
to that purity. Though maybe with a really big "getter" ... Mike K.

I have this image of someone walking in through the airlock with a
_big_ container of cesium or strontium, to be used as a getter, and
hooking it up to a pair of terminals on the inside of the tube once
it has been baked and pumped down for a while.

I also have this image of an enormous induction heater, with coils
completely surrounding the tube, forepumps the size of modern fanjet
engines, and diffusion pumps slinging kiloliters of oil per second.

Somehow, I think it's just not viable.

I believe that in Rocket Ship Galileo, Heinlein discussed vacuum tubes
on the moon. No external envelope needed, just shielding.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:

I believe that in Rocket Ship Galileo, Heinlein discussed vacuum tubes
on the moon. No external envelope needed, just shielding.

He did. Should make for _great_ transmitting-tube laboratories.

--
There are two product lines in which customers are called "users".
The other one is illegal drugs.
MWMeyer, viva voce personal communication

Mike Knudsen wrote:

I doubt there were ever walk-in tubes. The vacuum required for any kindof tube
life is so "hard" and pure that you wouldn't be able to pump out a whole room
to that purity. Though maybe with a really big "getter" ... Mike K.



I don't know about walk in tubes but I do recall visiting a UK Post
Office radio station many years ago and walking into the final
amplifier where there was at least one tube which I recall as being
around 4 or 5 feet high (maybe more) which had a water cooling system.
If it means anything to anyone the station was at Leafield in
Oxfordshire.

Dave

On Wed, 03 Mar 2004 22:47:32 -0500, Dave Holford
wrote:


Mike Knudsen wrote:

I doubt there were ever walk-in tubes. The vacuum required for any kindof tube
life is so "hard" and pure that you wouldn't be able to pump out a whole room
to that purity. Though maybe with a really big "getter" ... Mike K.

It's not that difficult.
Where I used to work we had vacuum chambers large enough for to get
in. We ran those down to 10^-7 torr.

OTOH we had some mass spectrometers that used ion pumps in addition to
the mechanical roughing pumps and the diffusion pumps.

Once past about 10^-2 torr, most of the molecules cling to the
surfaces and are basically scrapped off with the diffusion pumps.

After that there isn't a lot for the ion pumps as the things lasted
for years.

Course if we managed to burn out one of the induction heating coils
which was water cooled, it took days to clean up the mess.

You know it's gonna be a bad day whey there is water coming out the
roughing pump exhaust.

We once had a failure on the midnight shift that wasn't caught right
away. It filled up the entire exhaust system for a big room full of
float zone refining equipment. Now that was expensive.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com



I don't know about walk in tubes but I do recall visiting a UK Post
Office radio station many years ago and walking into the final
amplifier where there was at least one tube which I recall as being
around 4 or 5 feet high (maybe more) which had a water cooling system.
If it means anything to anyone the station was at Leafield in
Oxfordshire.

Dave