[ARC5] Crystal Question

[J. Forster]

A shielded current loop and portable SW receiver ids the easiest way to
track them down.

-John

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

> 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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>