[TowerTalk] Fwd: Insulated elements, Yes - No?

L L bahr pulsarxp at embarqmail.com
Tue Aug 5 21:57:09 EDT 2014


I guess I should add, assuming the elements are all grounded, so the offset would affect all the elements.
Lee, w0vt

----- Original Message -----
From: "L L bahr" <pulsarxp at embarqmail.com>
To: towertalk at contesting.com
Sent: Tuesday, August 5, 2014 8:54:40 PM
Subject: Re: [TowerTalk] Fwd:  Insulated elements, Yes - No?


This brings up a big question in my small mind.  Assuming you need to correct element length,  I can see you can use SWR to adjust the driven element.  But how do you correctly know how to correct or adjust the reflector, or for that matter any parasitic element?  During the Dark Ages when I first got licensed, you just made the reflector around 10% longer then the driven element.  How do you do it in 2014?  (I really don't want to think of remote field strength measurements while adjusting the parasitic element.)  If you correct the driven element by 1 inch to lower the SWR, do you then just adjust the reflector by the same amount?
Lee, w0vt





Insulating the elements will certainly reduce the correction for the
boom and mounting plate, but does not eliminate corrections completely.
There is still a proximity effect, which will obviously be greater for a
mounting that uses thin insulating sleeves than it would be if the
element is spaced farther away from the metalwork on  substantial
insulating blocks.

Corrections for element mountings are subject to some uncertainties, so
it is always preferable to use a mounting method that involves smaller
correction in the first place.
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