[ARC5] Magnetron/Klystron 1936-40

Sun Nov 17 00:21:13 EST 2013

The magnetron is essentially a power oscillator and a not very clean one at
that.  But it can be scaled up to provide powerful pulses of microwave
energy. The klystron can be used much like a tube and is quite versatile.
 It can be a clean oscillator or an amplifier, can employ feedback, and it
modulates well.  It doesn't scale up to large powers like a magnetron.
 They each had their role in WW2 and both were very important.  The
original British magnetron was hard to manufacture due to the cavities.
 After secretly sending it to the US via courier he Americans figured out
how to make it from a stack of stamped laminations vs hogging out a block.
 You probably have a magnetron in your kitchen.

Dennis AE6C

On Sat, Nov 16, 2013 at 11:11 AM, J. Forster <jfor at quikus.com> wrote:

> There were crystal detectors and bolometers in labs. The Rad Lab or
> Harvard's RRL built a 26odd GHz RADAR  but it was no good because of H2O
> absorbtion. I think Ed Purcell was involved.
>
> -John
>
> =================
>
>
>
> >   G'day list.
> >   This is interesting.  I remember a cover picture on the front page of
> >   Electronics Australia when I was in high school.
> >   (That was 457 BC, not BC-457)
> >   An article in the magazine featured the Varian brothers, and stated
> >   they developed the Klystron on a budget of $100, but this is an
> >   approximation.
> >   They were given a room to work in and a budget for materials of $100
> >   in exchange for 1/2 the royalties on the Klystron.
> >   They did this work between '36 and 39.
> >
> >   In contrast, the magnetron was developed in Manchester (or Birmingham)
> >   I forget which in 1940.  The Brits got more power from their unit, and
> >   their work assisted the US RADAR development a good deal.
> >  Cleeton got his PhD in the mid-30s, and he worked at about 1cm so ...
> >  this must be around 30GHz.  I'd take 24GHz as "close".
> >  Whatever he used - it swept the GHz region where ammonium absorbed.
> >  God only knows how they measured what they were doing at that
> >  frequency, back then.  Amazing!
> >  Anyway, Cleeton/Williams must have had more than an acorn 955 in their
> >  pocket.
> >
> >   What do other list readers know?
> >   This is interesting.
> >
> >   73 de Les Smith
> >   vk2bcu at operamail.com
> >
> >
> >
> >
> > On Sat, Nov 16, 2013, at 12:49, Geoff wrote:
> >> I thought the Brits and MIT Rad Lab developed the magnetron during WW2.
> >>
> >> Carl
> >>
> >>
> >> ----- Original Message -----
> >> From: "Tom Dawson" <wb3akd at earthlink.net>
> >> To: "David Stinson" <arc5 at ix.netcom.com>; "ARC-5 List"
> >> <arc5 at mailman.qth.net>
> >> Sent: Friday, November 15, 2013 2:50 PM
> >> Subject: Re: [ARC5] 77 GHZ
> >>
> >>
> >> >I think the prize goes to Cleeton and Williams at U Mich in the early
> >> '30's
> >> >for discovering the absorption spectra of Ammonia at 24 (I think)  GHz.
> >> >
> >> > Used Western Electric Magnetrons as models and scaled them down in
> >> size to
> >> > the desired frequency to generate the RF.
> >> >
> >> > Polished brass parabolic mirrors on transmit and receive, selenium rod
> >> as
> >> > a detector.
> >> >
> >> > Wavelength measured with metal diffration gratings.
> >> >
> >> > Ammonia at 1 ATM in a rubberized canvas bag, they observed absorption
> >> of
> >> > the microwave energy.
> >> >
> >> > The idea came from their consideration that if quantumtheory was true,
> >> > then there ought to be an absorption line at 24 GHz or so, and they
> >> found
> >> > it. Opened up the field of microwave spectroscopy, as far as I know.
> >> >
> >> > Pretty durn neat for the time.
> >> >
> >> > 73
> >> >
> >> > Tom
> >> > ----- Original Message -----
> >> > From: "David Stinson" <arc5 at ix.netcom.com>
> >> > To: "ARC-5 List" <arc5 at mailman.qth.net>
> >> > Sent: Friday, November 15, 2013 1:40 PM
> >> > Subject: Re: [ARC5] 77 GHZ
> >> >
> >> >
> >> >> Similar surprise:
> >> >> I have an Aircraft Radio Corporation 1945 catalog, flogging their
> >> surplus
> >> >> parts from cancelled contracts at the end of WWII.
> >> >> All kinds of Command Set parts being offered.
> >> >>
> >> >> But they were also offering feedlines, cavities
> >> >> and other "plumbing" for 21 GHZ.
> >> >> Who knew anyone was "plumbing" 21 GHZ in 1945?
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