FS: WW II Magnetron GL-5J29 marked Classified, NOS

[Robert Baer]

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

 

[Rich Grise]

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich

 

[Don Bowey]

On 9/22/05 1:10 PM, in article pan.2005.09.22.20.12.32.748884@example.net,
"Rich Grise" <rich@example.net> wrote:

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich

As I recall the eBay listing, it was stated that the magnet was not
included. Of course that means the cavities are also missing. You are
correct that what is left isn't a magnetron.

Don

 

[Genome]

"Don Bowey" <dbowey@comcast.net> wrote in message
news:BF585F56.12297%dbowey@comcast.net...

On 9/22/05 1:10 PM, in article pan.2005.09.22.20.12.32.748884@example.net,
"Rich Grise" <rich@example.net> wrote:

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich



As I recall the eBay listing, it was stated that the magnet was not
included. Of course that means the cavities are also missing. You are
correct that what is left isn't a magnetron.

Don

What's the point of having cavities in your magnetron if the glass gets in
the way of the electerons?

DNA

 

[Rich Grise]

On Thu, 22 Sep 2005 20:58:58 +0000, Genome wrote:

"Don Bowey" <dbowey@comcast.net> wrote in message
"Rich Grise" <rich@example.net> wrote:
On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

As I recall the eBay listing, it was stated that the magnet was not
included. Of course that means the cavities are also missing. You are
correct that what is left isn't a magnetron.

What's the point of having cavities in your magnetron if the glass gets in
the way of the electerons?

I'm surmising that this goes into a BMF magnetron, where that the
cathode is a cylinder 2" ID, that that globe slides into and heats by
IR. Once the back-bombardment starts, you don't need much heater power
to a maggie at all. I worked on a couple of maggie xmtrs in the USAF,
and one of our favorite circuits was the filament control loop -
it sensed the filament resistance (ergo temperature), and adjusted
the filament drive to maintain the right temp.

And I've seen several different types of magnetrons, and I've _never_
seen one with the cavities integral to the magnet. Usually the anode
is a solid block of copper with the cavities milled out of it.

Cheers!
Rich

 

[Jim Adney]

On Thu, 22 Sep 2005 03:10:37 GMT Robert Baer
<robertbaer@earthlink.net> wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

I've got 2 tubes that look just like this sitting in a cabinet in my
office. They were there when I moved in, so I'll have to ask someone
what they are. I'll have more info tomorrow.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[John Fields]

On Thu, 22 Sep 2005 22:15:49 GMT, Rich Grise <rich@example.net>
wrote:

On Thu, 22 Sep 2005 20:58:58 +0000, Genome wrote:
"Don Bowey" <dbowey@comcast.net> wrote in message
"Rich Grise" <rich@example.net> wrote:
On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

As I recall the eBay listing, it was stated that the magnet was not
included. Of course that means the cavities are also missing. You are
correct that what is left isn't a magnetron.

What's the point of having cavities in your magnetron if the glass gets in
the way of the electerons?

I'm surmising that this goes into a BMF magnetron, where that the
cathode is a cylinder 2" ID, that that globe slides into and heats by
IR. Once the back-bombardment starts, you don't need much heater power
to a maggie at all. I worked on a couple of maggie xmtrs in the USAF,
and one of our favorite circuits was the filament control loop -
it sensed the filament resistance (ergo temperature), and adjusted
the filament drive to maintain the right temp.

And I've seen several different types of magnetrons, and I've _never_
seen one with the cavities integral to the magnet. Usually the anode
is a solid block of copper with the cavities milled out of it.

---
http://www.r-type.org/exhib/aac0088.htm
--
John Fields
Professional Circuit Designer

 

[Pooh Bear]

Rich Grise wrote:

On Thu, 22 Sep 2005 20:58:58 +0000, Genome wrote:
"Don Bowey" <dbowey@comcast.net> wrote in message
"Rich Grise" <rich@example.net> wrote:
On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

As I recall the eBay listing, it was stated that the magnet was not
included. Of course that means the cavities are also missing. You are
correct that what is left isn't a magnetron.

What's the point of having cavities in your magnetron if the glass gets in
the way of the electerons?

I'm surmising that this goes into a BMF magnetron, where that the
cathode is a cylinder 2" ID, that that globe slides into and heats by
IR. Once the back-bombardment starts, you don't need much heater power
to a maggie at all. I worked on a couple of maggie xmtrs in the USAF,
and one of our favorite circuits was the filament control loop -
it sensed the filament resistance (ergo temperature), and adjusted
the filament drive to maintain the right temp.

And I've seen several different types of magnetrons, and I've _never_
seen one with the cavities integral to the magnet. Usually the anode
is a solid block of copper with the cavities milled out of it.

And the qaulityof the copper is imporant too.

Graham

 

[Pooh Bear]

Rich Grise wrote:

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich

This is better.

http://www.tubecollector.org/5j29.htm

Certainly not a *resonant cavity magnetron*.

Graham

 

[Joe McElvenney]

Hi,

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

It is a split anode magnetron with the filament (and its
tensioner) visible just under half way along from were the pipes
enter. From there it passes through a disc that is designed to
stop electrons being sprayed out onto the glass envelope and then
into the space between the two anodes. The thick pipe is both for
tuning and water cooling - one of the filament connections being
visible next to the water inlet. The reason there is usually no
magnet with these tubes is that it is left behind in the
equipment.

This type of tube was known before WW-II being developed by both
the Germans and the Japanese. There are no cavities in it, the
anode being made of two blocks with semicircular cutouts allowing
room for the electrons to swirl around under the influence of the
magnetic and electric fields; operation being rather similar to
the well known cyclotron. Randall and Boot's cavity magnetron
didn't really come onto the scene until about 1940.


Cheers - Joe

 

[Andrew VK3BFA]

Joe McElvenney wrote:

Hi,

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

It is a split anode magnetron with the filament (and its
tensioner) visible just under half way along from were the pipes
enter. From there it passes through a disc that is designed to
stop electrons being sprayed out onto the glass envelope and then
into the space between the two anodes. The thick pipe is both for
tuning and water cooling - one of the filament connections being
visible next to the water inlet. The reason there is usually no
magnet with these tubes is that it is left behind in the
equipment.

This type of tube was known before WW-II being developed by both
the Germans and the Japanese. There are no cavities in it, the
anode being made of two blocks with semicircular cutouts allowing
room for the electrons to swirl around under the influence of the
magnetic and electric fields; operation being rather similar to
the well known cyclotron. Randall and Boot's cavity magnetron
didn't really come onto the scene until about 1940.


Cheers - Joe

Thanks Joe - nice tutorial!

Andrew VK3BFA.

 

[Don Bowey]

On 9/23/05 3:22 AM, in article 4333D771.D457936A@hotmail.com, "Pooh Bear"
<rabbitsfriendsandrelations@hotmail.com> wrote:

Rich Grise wrote:

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich

This is better.

http://www.tubecollector.org/5j29.htm

Certainly not a *resonant cavity magnetron*.

Graham

Well of course it is. The cavity (or cavities) are part of the magnet
assembly.

Don

 

[Rich Grise]

On Fri, 23 Sep 2005 04:35:33 -0500, John Fields wrote:

On Thu, 22 Sep 2005 22:15:49 GMT, Rich Grise <rich@example.net

... Usually the anode
is a solid block of copper with the cavities milled out of it.

---
http://www.r-type.org/exhib/aac0088.htm

Oh, well that's different.

Never mind.

 

[Rich Grise]

On Fri, 23 Sep 2005 11:22:41 +0100, Pooh Bear wrote:

Rich Grise wrote:

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich

This is better.

http://www.tubecollector.org/5j29.htm

Certainly not a *resonant cavity magnetron*.

OK, so the copper pipe isn't BMF filament. Then, it must be
the plate inductor*, or something like that.

Thanks,
Rich
* in addition to being the water "jacket".

 

[Rich Grise]

On Fri, 23 Sep 2005 08:01:46 -0700, Don Bowey wrote:

On 9/23/05 3:22 AM, in article 4333D771.D457936A@hotmail.com, "Pooh Bear"
Rich Grise wrote:
On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

This is better.

http://www.tubecollector.org/5j29.htm

Certainly not a *resonant cavity magnetron*.

Well of course it is. The cavity (or cavities) are part of the magnet
assembly.

No, it's a split-anode magnetron (I've changed my tune). The anode(s)
is/are those two copper blocks at the base of that loop of pipe. And
I'm guessing that that loop of pipe is a shorted transmission line
at the opreating freq. The magnetic field goes axial to the filament,
and the electrons swirl around, like a cyclotron. John Fields posted
a link to another 5J29 page that calls that out.

Thanks,
Rich

 

[Don Bowey]

On 9/23/05 10:29 AM, in article pan.2005.09.23.17.31.22.152025@example.net,
"Rich Grise" <rich@example.net> wrote:

On Fri, 23 Sep 2005 08:01:46 -0700, Don Bowey wrote:
On 9/23/05 3:22 AM, in article 4333D771.D457936A@hotmail.com, "Pooh Bear"
Rich Grise wrote:
On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

This is better.

http://www.tubecollector.org/5j29.htm

Certainly not a *resonant cavity magnetron*.

Well of course it is. The cavity (or cavities) are part of the magnet
assembly.

No, it's a split-anode magnetron (I've changed my tune). The anode(s)
is/are those two copper blocks at the base of that loop of pipe. And
I'm guessing that that loop of pipe is a shorted transmission line
at the opreating freq. The magnetic field goes axial to the filament,
and the electrons swirl around, like a cyclotron. John Fields posted
a link to another 5J29 page that calls that out.

Thanks,
Rich

Your research is incomplete.

Don

 

[Reg Edwards]

"Joe McElvenney" wrote

Randall and Boot's cavity magnetron
didn't really come onto the scene until about 1940.

===========================

R & B's cavity magnetron was developed at Birmingham University in the
midst of the air raids on that industrial city. We can imagine R & B
having to hide under the workbench whenever a descending bomb was
heard, culminating in a loud bang and broken glass.

The ingenious device generated a peak pulse power of 50 kilowatts at
3000 MHz. Pulse repetition frequency 400 Hz. Pulse width 1
microsecond. So far as I can remember there were 6 or 8 cavities
milled into the copper block. Alternate anodes surrounding the
cathode, and close to it, were strapped together at their ends via
copper bars. The block diameter was about 2" and about 1" thick. The
magnet was a U-shape with pole-pieces which closely fitted the flat
ends round the block such that the magnetic field was parallel to the
cathode.

Because the luftwaffer in 1940/1 had more bombers than the RAF, and in
view of its potential as a war weapon, Churchill personally banned
installation in RAF aircraft in case the top-secret device should be
shot down over Germany and fall into the hands of German scientists
and engineers.

So Churchill handed the cavity magnetron to Roosevelt as a free gift
in return for 50 rusty, old, WW1 destroyers. The manufacturing
capacity of the US radio industry far exceeded that of the UK. Not to
be outdone, the Americans soon produced a 10,000 MHz version.

I first held one in my hands in 1945 by which time centimetric radar
had been installed in RAF Catalina and Sunderland flying boats on
convoy-escort duties in the Battle of the Atlantic. By 1945 German
submarine crews were on suicide missions like kamikazi pilots, only 1
U-boat in 10 returned to base.

There are more than 100,000 merchant ship and U-boat crew-members
sharing Davy Jones locker at the silent bottom of the North Atlantic
Ocean.

Once having detected a centimetric radar beam, and being accurately
located themselves, submarine commanders preferred to remain on the
surface, uncover the guns, and fight it out, day or night.

During most of the war there had been little effect on German
industrial production by RAF raids. Many bombs fell on open fields and
sometimes killed cattle. But by 1944 RAF navigatigators had maps of
rivers and cities laid before them. More than a 1000 heavy bombers,
Lancasters, could be put into the air, night after night.

With radar they couldn't miss whole cities and individual districts.
Nevertheless on one occasion more than 100 bombers, complete with
crews, failed to return to base. Such occurrences greatly exceeded the
capacity of factories to produce them and to train aircrews.

During the last 12 months of the war, radar equipped RAF bombers
killed more German civilians than died in the concentration camps.
Hiroshima and Nagasaki, which came shortly after, were just chicken
feed. Air Marshal "Bomber" Harris was never knighted for services
rendered.

The main beneficiaries of R & B's invention of the cavity magnetron,
done amid the high-explosives and incendiaries falling on Birmingam,
have been the Japanese and other Far Eastern peoples who have
manufactured many millions of cheap, reliable, microwave ovens.

And of course the many millions of people like you and I who benefit
from daily hot meals. I detest barbiques.

There was held in the Kensington, London, Science Museum, the original
prototype of the cavity magnetron without its magnet. It was in a
securely locked mahogany and glass case and looked, as I recollect,
like a small dirty can of baked beans with things sticking out of it.
It may still be there.

Makes a change from so-called SWR meters.
----
Reg, G4FGQ.

 

[John Woodgate]

I read in sci.electronics.design that Reg Edwards
<g4fgq.regp@ZZZbtinternet.com> wrote (in
<dh1ejs$e5d$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com&gt about 'FS: WW II
Magnetron GL-5J29 marked Classified, NOS', on Fri, 23 Sep 2005:

So Churchill handed the cavity magnetron to Roosevelt as a free gift in
return for 50 rusty, old, WW1 destroyers.

They were a very great deal better than not having them.

The manufacturing capacity of the US radio industry far exceeded that
of the UK. Not to be outdone, the Americans soon produced a 10,000 MHz
version.

I think that's a bit off-beam. The 3 cm device was a joint UK-US
effort. But, to a very large extent, once the principles, in particular
the cross-strapped anodes for mode suppression, were established at 10
cm, the 3 cm device was a matter of dividing the dimensions by 3.33.

--
Regards, John Woodgate, OOO - Own Opinions Only.
If everything has been designed, a god designed evolution by natural selection.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Pooh Bear]

Don Bowey wrote:

On 9/23/05 3:22 AM, in article 4333D771.D457936A@hotmail.com, "Pooh Bear"
rabbitsfriendsandrelations@hotmail.com> wrote:

Rich Grise wrote:

On Thu, 22 Sep 2005 03:10:37 +0000, Robert Baer wrote:

Have listed at Ebay, number: 7352596690
WW II Magnetron GL-5J29 marked Classified, NOS
A genuine collector's item.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7352596690

Well, I don't know what it is, but it ain't a magnetron!

It looks like nothing but a big filament. Maybe it slid into
a 2" diameter cathode in a really really big magnetron, (magnetron
heater?) but what's in that picture is NOT a magnetron!

Good Luck!
Rich

This is better.

http://www.tubecollector.org/5j29.htm

Certainly not a *resonant cavity magnetron*.

Graham

Well of course it is. The cavity (or cavities) are part of the magnet
assembly.

Don

Wrong Don !

Graham

 

[Rich, Under the Affluence]

On Fri, 23 Sep 2005 22:08:15 +0100, John Woodgate wrote:

I read in sci.electronics.design that Reg Edwards
g4fgq.regp@ZZZbtinternet.com> wrote (in
dh1ejs$e5d$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com&gt about 'FS: WW II
Magnetron GL-5J29 marked Classified, NOS', on Fri, 23 Sep 2005:

So Churchill handed the cavity magnetron to Roosevelt as a free gift in
return for 50 rusty, old, WW1 destroyers.

They were a very great deal better than not having them.

The manufacturing capacity of the US radio industry far exceeded that
of the UK. Not to be outdone, the Americans soon produced a 10,000 MHz
version.

I think that's a bit off-beam. The 3 cm device was a joint UK-US
effort. But, to a very large extent, once the principles, in particular
the cross-strapped anodes for mode suppression, were established at 10
cm, the 3 cm device was a matter of dividing the dimensions by 3.33.

There's something I've wanted to ask since the microwave portion
of USAF tech school. It didn't come up, because my specialty was
ECM (Electronic CounterMeasures), and all of the transmitters in
that field are intentionally as noisy as possible, since their
purpose in life is to jam.

But for, for example, radar, does a magnetron normally put out
a relatively "clean" sine wave? One of our jamming transmitters
was series-modulated with a 4-400A. (I once checked a brand-new,
in-the-box 4-400A out of Bench Stock and gave it to a buddy
who built a 20M linear with it. Being a tech in the USAF was
kewl. ;-) )

Anyway, I know they're typically pulsed for radar, and a
microwave oven doesn't care about the waveform; in fact, probably
the raggedier/noisier the better for something like that, but
during a radar pulse, is it putting out a clean signal?

Thanks,
Rich