[ARC5] 77 GHZ

[Leslie Smith]

  Hello Tom,
  This is pretty interesting, I'd like to know more.
  Where can I read about this?

  Recently I've been repairing older Varian NRM spectrometers, and the
  precision of the signals (wrt frequency) is astonishing.
  Flipping a proton (in a molecule) results in a frequency shift of
  several Hz - measured at 90.000 MHz.
  Fascinating - and this is measured using 1970's technology.  No uP,
  nothing digital, even the chart-recorder used the older motor and
  error pot to position the pen.
  All that - and it still works nicely.

  73 de Les Smith
  vk2bcu at operamail.com


On Sat, Nov 16, 2013, at 6:50, Tom Dawson wrote:
> 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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