[TowerTalk] Tuning a 20m 4-Square Array - detuning other verticals?

[Larry K4AB]

Hello Mike,

The key in any 4 square system is the dump power.
Can you perhaps use a dummy load in the shack and
run a 150' coax to the array?

Also, the antenna lengths need to be LONGER than
a normal single vertical.  Around 5% or so.  But
the only way to be sure is to measure the dump power.

GL!

73,
Larry K4AB

On Tue, May 12, 2015 at 7:52 PM, Mike Smith VE9AA <ve9aa at nbnet.nb.ca> wrote:

> OK, so I just put up a 20m 4-square using a COMTEK box.  So far, I'm a
> fairly  happy camper.  First real gain antenna on 20m in 11 yrs. (gain
> being
> a subjective term here)
>
> Installed the first skinny vertical. 2 raised radials @ 90 degrees to one
> another.  The vert's about 2' off the ground and so are the 2 radials. SWR
> curve looked really awesome once I tweaked the length of the radials and
> vertical element.
>
> I was in heaven.
>
>
>
> Unfortunately the way it's arranged, each vert only has 2 raised radials
> and
> if you were looking at it from overhead, you would only see a square and a
> vertical at each corner.  The raised radials for each vertical are adjacent
> to one another.  I tried 1 radial each, but SWR was high no matter how much
> tweaking I did or what angle(s) I had it at.  I cannot do ground radials,
> nor radials extending out past the 4 lines of the 17.5'x17.5' box.  I could
> do one more (very bent)  radial towards the center of the box, but that's
> it.  I don't think it would help.  I digress.
>
>
>
> I put up 3 more verts and built them as close as I could to the original.
> Carbon copies.
>
>
>
> Let's not talk SWR curves, but how to go back and retweak all the verticals
> independantly?  What I am seeing in the shack baffles me. *(must be the
> hybrid cct in the  external box doing weird things to my SWR analyzer) I am
> going round and round.
>
>
>
> When I was doing the 2nd vertical, I tried shorting the center to the braid
> on the original but in all honesty I don't think it made much difference.
>
>
>
> The array is "working" (F/B great, F/S is "MEH", but I am not really seeing
> any gain in the favored direction that I can quantify over another vertical
> 50-60' away. (HF9V).  It IS much quieter and that's really  nice and I do
> hear W1's on backscatter (vy weakly) that I cannot hear on the HF9V(QRN)
> but
> I see no real difference on the S-meter on signals above the S1-QRNy noise
> floor.  I am looking for 3dB (or that's my hope)  Some SSB signals sound
> different on the 4-SQ compared to the HF9V, so I am presuming a different
> incoming angle or possible a dB or two of gain, but nothing I can measure.
> The quietness is comforting, due to some noise to the NW and other small
> sources in other directions.
>
>
>
> I have a ton of questions and probably could give lots more details on how
> I
> have this thing built and why only 2 raised radials etc., but if I could
> nail down detuning the "other 3", I think I would be on the right road.
>
> Bottom line, what's the best way, short of taking down the "other 3"
> verticals to detune them? (could I clip a 4' wire onto the bottom of them
> or
> something?)
>
>
>
> I have not yet measured dumped power into the dummy load.  Antennas are
> ~150' from the house and it's been raining here, so quick dashes outside
> only...just got control cable working at suppertime.  I can enlist my son
> as
> a helper to do some key down sessions once the wx clears this weekend. I am
> told the frequency at which I see the least power dump is where my array is
> most resonant and has the most gain at ?
>
>
>
> TKS
>
>
>
> Mike VE9AA
>
>
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>
>
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