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[TowerTalk] crosstalk between beams on a common boom (such as c31xr)

To: <towertalk@contesting.com>
Subject: [TowerTalk] crosstalk between beams on a common boom (such as c31xr)
From: "Al Williams" <alwilliams@olywa.net>
Date: Fri, 18 Mar 2005 21:11:04 -0800
List-post: <mailto:towertalk@contesting.com>
For example, transmitting on a 20 meter beam while listening on a 15 meter beam.

How great is the risk of damaging the front end of a receiver listening on one 
beam while transmitting on a second beam
when both are close spaced?

I used EZNEC briefly and was surprised that a parasitic element of the same 
dimension results in current in the parasitic
almost as high as the driven element (for a spacing of about 4 feet) .However, 
changing the parasitic length to another band 
dropped the current down to about 20 % of the driven element.

But I don't have any idea of the relationship of current in the parasitic 
element to that obtained when the parasitic element
is actually the driven element on another beam.  I tried putting a 50 ohm load 
in the parasitic element and that dropped 
the parasitic element current even more.

But, since the frequency of the signal on the 15 meter beam is 20 meters, I 
presume that the SWR is high and a
voltage amplification may result depending on the transmission line length.

BTW, I would be using Dunestar filters on both rigs, but am concerned about 
inadvertently not having the filter turned
on at some time.

looking forward to explanations

k7puc
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