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[TowerTalk] problems with 10m COMTEK 4 sq unit

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Subject: [TowerTalk] problems with 10m COMTEK 4 sq unit
From: (
Date: Sun, 18 Mar 2001 16:50:33 EST
In a message dated 3/18/2001 14:51:27 Eastern Standard Time, writes:

>  If you build the proper feedlines so you have approx 50ohms of +J (3/8WL
>  feedline 50 ohms) You can make the unpowered dipoles act as reflectors. 
>  This kind of array has its beginings with the old K8UR array which had 5
>  dipoles pulled out from a single tower.

I have tried that and have one working right now. If I set the individual 
radiators (3x) for 50 ohm impedance and run the array as 1 radiator with two 
stub tuned reflectors, the impedance is fine, 50 ohms (F/B or pattern is less 
than what I would like to have), but when I switch to other configurations 
(two radiators, one reflector) impedance changes (hard to see any pattern, 
any time). Behaves the same here with soaked (average) ground and by the salt 
water. It seems that parasitic vertical arrays suck (for max F/B).
    This is why I am trying to get 4 square going, which provides (on the 
screen) much better pattern, but probable problem with my controller and lack 
of explanation how them boxes work, what is exactly required, how to test it 
and how to fix or tune in case of variation in antenna elements is hampering 
    We have situation where we can model the stuff, but are presented with 
box that should work, just plug it in (trust me, it works :-). Some 
explanation and specifications would go long way in helping us to use and 
adapt them properly.
    When I first got instructions for 80m Comtek box and we wired it up at 
VE1ZZ, the numbering in the instruction book was confusing, ports, directions 
and positions on the switch were numbered 1,2,3,4 each meaning different 
thing (and not correlated). My new instructions have corrections by hand 
after I brought it up. (After operating contest beaming wrong ways, still 
good enough for world #1 :-)
    I have gone through W4RNL material, it is excellent work (on paper) and 
saved me some digging and fooling around, but things are not as easy with 
real life wires and tubing and magic boxes. 
    It looks like my problem might be caused by faulty ACB-10 box and 
possible problem with radiator's impedances of abt 110 ohms being out of 
range for it.
    I need sharp, vertical switchable array on the beach to complement the 
rest of the antenna artillery, this is why I am persuing 4 sq.
    I also managed to model 3 el. Quad and I was pleased to find that 
computer says that (I was right) Quads are not as dumb as some say. 
    I think Stackmatch will be ideal for switching and phasing between 
different antenna systems, but this parasitic triangular array is not what it 
looks like on the computer or what what I would like. Anybody else have other 
    Clock is ticking and I am sitting (again) with bunch of (mismatched) 
vertical dummies, but living, learnig and enjoying every (frustrated) minute 
of it :-) Been there before, will do it again.

Thanks for any light sheding input!


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