[ARC5] Crystal Question

[Michael A. Bittner]

Don't forget the electrolytic detectors of  Reginald Fessenden.  Mike, W6MAB

  ----- Original Message ----- 
  From: Dennis Monticelli 
  To: jfor at quik.com ; Discussion of AN/ARC-5 military radio equipment. 
  Sent: Friday, November 12, 2010 9:02 AM
  Subject: Re: [ARC5] Crystal Question


  Not only rain gutters but wire fencing or decrepid old TV antennas or any
  long metal run that has metal-to-metal mechanical contacts along the way
  that corrode upon exposure to reactive elements in the atmosphere.  Nearby
  AM BCB antennas are the usual source of the fundamental energy.  I recently
  experienced terrible mixing products in my HF receivers that took weeks to
  track down.  It turned out to be a hairline broken connection at the
  feedpoint of one of my wire antennas. The wire was copperweld and the
  connection was covered with RTV.  All looked well from the outside and in
  trasmit the SWR was just fine as the large signal crashed right across the
  gap.  But inside was a barely touching joint that had failed due to fatigue
  and in receive it made a great Schottky detector.

  I think the liquid electrolyte rectifiers of old were used in the early
  power supplies.  The speed of ion transport in solution was probably too
  slow to be useful as an RF detector.

  Dennis AE6C

  On Fri, Nov 12, 2010 at 8:01 AM, J. Forster <jfor at quik.com> wrote:

  > > Good Morning (UTC +1 time),
  > >
  > > Re my comment yestereday about metal-on metal
  > > rectifying RF:
  > > One of my experiments was using the contacts
  > > on my J-38 and home brew keys as detector
  > > by adjusting the spacing so that the
  > > oxidized contact surfaces barely made contact.
  > >
  > > On the more curious side, some have experienced
  > > having there tooth fillings function as detectors of broadcast
  > > signals.
  > >
  > > One of the causes of TVI often seen in densely populated areas
  > > is the fact that overlapping metal objects (e.g. rain gutters) not
  > > having good galvanic connection will rectify RF transmissions
  > > and create harmonics.
  >
  >
  > This is certainly true. A friend lives near a few powerful AM stations and
  > gets third order mixing products all the time. He has spent weeks chasing
  > then down.
  >
  > Best,
  >
  > -John
  >
  > ==============
  >
  >
  > > BTW didn't early radio detectors also include liquid electrolytic
  > > solutions?
  > >
  > > Henry, Cph.
  >
  >
  >  ______________________________________________________________
  > ARC5 mailing list
  > Home: http://mailman.qth.net/mailman/listinfo/arc5
  > Help: http://mailman.qth.net/mmfaq.htm
  > Post: mailto:ARC5 at mailman.qth.net
  >
  > This list hosted by: http://www.qsl.net
  > Please help support this email list: http://www.qsl.net/donate.html
  >
  ______________________________________________________________
  ARC5 mailing list
  Home: http://mailman.qth.net/mailman/listinfo/arc5
  Help: http://mailman.qth.net/mmfaq.htm
  Post: mailto:ARC5 at mailman.qth.net

  This list hosted by: http://www.qsl.net
  Please help support this email list: http://www.qsl.net/donate.html