[TowerTalk] properly feeding a tribander stack

Tom Hammond - N0SS n0ss@earthlink.net
Sun, 17 Oct 1999 17:17:39 -0500


Press:

For what little it may be worth...

The ARRL should either already have, or should soon have, the
text/diagrams/etc. from Walt's QST series "Another Look At
Reflections" somewhere ON their web site.  I scanned it in
about 8 months ago, sent it to them, and they said they were
in the process of getting it up and on-line.

I still have the complete series as an MS Word for Windows 97
.DOC file (about 500kB, if I recall), if anyone wants it. But
PLEASE, first see if you can get it from the ARRL.  That way
I won't have to send it to you over MY modem.

73 - Tom Hammond   N0SS

N8UG wrote:

>Hi Pete - Your query brings to mind a few words from  Walt Maxwell. in
>"Reflections,"
>"All power fed into the line, minus the amount lost in line attenuation,
>is absorbed in the load regardless of the mismatch at the antenna
>terminals"
>
>This gives credence to your operating premise, in agreement with others
>of W2DU's ilk qualified to speak.
> 
>I would suggest that your "local"  watch for Walt's new book, due out by
>years end, or, if he really wants to tell it like it is, find a friend
>who will loan him a copy of "Reflections" in the meantime.
>
>73,
>
>
>Press Jones, N8UG, The Wireman, Inc., Landrum, SC, 29356
>Sales (800)727-WIRE(9473) or  orders@thewireman.com
>Tech help (864)895-4195 or  n8ug@thewireman.com
>http://www.thewireman.com  and the WIRELINE news 
>and bargain page.  Our 22nd year!
> 
>
>On Sun, 17 Oct 1999 03:17:55 +0100 Pete Smith <n4zr@contesting.com>
>writes:
>> 
>> I have been operating all along on the premise that in feeding a 
>> stack it
>> is sufficient to have equal feedline lengths from a common feedpoint 
>> such
>> as a stackmatch, in order to feed the driven elements in phase.  Now 
>> a
>> local has said that the feedlines should not only be equal in length 
>> but
>> also an odd number of quarter waves in length.  I vaguely recall a
>> discussion of stacking several years ago on Towertalk in which one 
>> of the
>> established experts said that it was necessary to do this to force 
>> equal
>> currents in the driven elements, for the best possible pattern.
>> 
>> Obviously, having to switch feedlines in order to meet this 
>> criterion would
>> significantly complicate a typical tribander stack.  Does anyone 
>> know:
>> 
>> 1.  Is this true, even in the abstract?
>> 
>> 2.  If it is, quantitatively, how significant is it?
>> 
>> 73, Pete Smith N4ZR
>> n4zr@contesting.com 
>> 
>> Sometimes a tower is just a tower
>> 
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>
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