[TowerTalk] Tuning raised radial verticals

[Bryon Paul Veal NØAH]

this is why I prefer a comtek hybred coupler.....I would suggest you look into one.  You will use 75 ohm coax due to velocity factors but any RF feeding back due to SWR is burned off in a dummy load. You feed the coupler with 50 ohm coax from the shack and from the coupler, in the center of the 4 sqr, 75 ohm coax to the verticals. 50 ohm coax  would be too short based upon velocity factors.  You can see one I built on my qrz.com<http://qrz.com> page.   I recall each vertical in this system is exactly like the other and is tuned for the desired frequency.  I also wrote substantial reports you can find in towertalk archives at www.contesting.com<http://www.contesting.com> under n0ah in 1999, 2000

GL

73 de paul N0AH

DXengineering sells them.

73

paul. N0AH

73

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On August 31, 2017 3:23:32 PM Rudy Bakalov <r_bakalov at yahoo.com> wrote:

I am measuring the impedance at the very base of the vertical with a calibrated RigExpert. According to DX Engineering the vertical should be connected without any baluns, matching networks...nothing. Furthermore, they are saying that the vertical should be resonant 4% of the target array frequency. That is, in my case, if I want to tune the array for 3.550 each individual vertical should be tuned for 3.413.

Rudy N2WQ
________________________________
From: Bryon Paul Veal NØAH <bryonveal at msn.com>
To: Rudy Bakalov <r_bakalov at yahoo.com>; Towertalk Reflector <towertalk at contesting.com>
Sent: Thursday, August 31, 2017, 4:34:40 PM EDT
Subject: Re: [TowerTalk] Tuning raised radial verticals

your seeing changes in the FEEDPOINT impedance using a tuned raised radial,
thus your SWR will move  if yoy mess with them.  Suggest you consider using
UnUns at the feedpoints to match the coax impedence to that of the
verticals.  Also, a Comtek hybred coupler.....

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On August 31, 2017 12:23:04 PM Rudy Bakalov via TowerTalk
<towertalk at contesting.com<mailto:towertalk at contesting.com>> wrote:

> Hi folks,
> I am building my 80m 4SQ. The elements are made of wire attached to 8'
> poles and then raised radials also about 8' above the ground. While tuning
> the verticals we observed an unexpected behavior- shortening the vertical
> wire has almost zero effect on the resonant frequency, while shortening the
> radial does. Is this behavior normal? What is the best approach to tuning
> verticals with a single raised radial?
> 73, Rudy N2WQ

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