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Old July 7th 06, 02:29 AM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jul 2006
Posts: 349
Default --W8ji-- Faraday shield

Hi Tom,
I'm winding some Flag antenna transformers and measuring
capacitance between pri. and sec.

A one point somewhere you said ;
" The proper grounding point for a Faraday shielded primary
is opposite the exit point of the primary winding, or on the
secondary winding's exit side of the transformer. Most Faraday
shields described for Beverages and other transformers are
not only useless, they are often incorrectly grounded and
actually increase unwanted coupling!"

Sorry if this out of context, I'm just trying to get info.

Btw. I'd like to apply any response to potcore transformers.

Is the exit point you mention related to the impedance of the winding?
Do I want to exit with the lower impedance winding?
If I use a Faraday shield, the grounding wire is a 15ft horizontal run
and a 20ft vertical drop, before earth ground. Is it still reasonable to
think it will work?
Mike


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Old July 7th 06, 03:01 AM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jul 2006
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Default --W8ji-- Faraday shield


amdx wrote:

Is the exit point you mention related to the impedance of the winding?


I added a "flying winding" to balance the seconday capacitance to
ground, not to reduce it or shield it.

Do I want to exit with the lower impedance winding?


I'm not sure what you mean. What I did won't work in other
configurations.

If I use a Faraday shield, the grounding wire is a 15ft horizontal run
and a 20ft vertical drop, before earth ground. Is it still reasonable to
think it will work?


No. The "faraday shield" will likely just couple signals and noise from
the ground lead right into the antenna. I'd avoid the whole thing, and
just separate the windings as much as losses allow. Hopefully you are
using small low capacitance windings.

73 Tom

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