[TowerTalk] four square array tuning

[Peter Voelpel]

Hi Steve,

You need to OPEN the unused radiators while you adjust one at the time!

If connected to ground they couple to the radiator in tune.

73
Peter, DJ7WW

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Steve
Bookout
Sent: Montag, 28. November 2016 23:28
Cc: towertalk at contesting.com
Subject: [TowerTalk] four square array tuning

Hello all,

Over the last few years, I have added four square arrays for 40 meters 
and 80 meters, and both work really outstanding.

Recently, I added a third one for 20 meters and am having a difficult 
time with it.

Short version is I resonated each antenna individually, with the others 
shorted with clip leads to gnd, to 13.9 MHz +/-.  The array, as a whole, 
doesn't show a suitable SWR until 15.6 MHz! Like the others I had 
installed, I was expecting a 150 KHz, or so, rise in frequency to 
resonance.  I do understand that it's really all about the power being 
dumped to the dummy load, but the amp is not going to tolerate a 3.5 to 
1 SWR.

Cables were cut using an AIM antenna analyzer and were double checked.  
All other cable/parts were checked out and shown to be correct.

80 ground mounted radials under each antenna.

Built just like I did the other two.

Gonna look at it with an O-scope tomorrow and check phase vs freq.  My 
gut feeling is an incorrect value component.

My gut feeling aside, I would appreciate any ideas.

73 de Steve, NR4M

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