[ARC5] Crystal Question

[Dennis Monticelli]

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.
>
>
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