[TowerTalk] Tuning raised radial verticals

[Rudy Bakalov]

This is becoming a troubleshooting exercise now.
I tuned all verticals to around 3,413. Each vertical has a 70' element and 68.5' single radial about 7' above the ground. RigExpert measures SWR around 1.1 and impedance of ~60 Ohms with very little, if any, reactive components. So far so good.
Then I connect the DXE box and get the following readings:
Position 1: SWR 1.01 @ 3.512 MHz and below 1.5 across the band
Position 2: SWR 1.13 @ 3.368 MHz and below 1.5 across the band
Position 3: SWR 1.0 @ 3.738 MHz and below 1.5 across the band
Position 4: SWR 1.18 @ 3.353 MHz and below 1.5 across the band
Omni: SWR 1.11 @ 3.370 MHz and shoot well above 5 across the band
Position 1 makes sense, but the rest do not.
I called DXE and they could not offer much of an advice. The obvious troubleshooting they'd like to do is test the unit for the Omni position and I will send it back to them. Does the rest of the array make sense?
DXE tells me that their box expects to see about 30-40 Ohms at the base of each vertical and that my raised single radial would not work. Should I add more raised radials? ON4UN's book seems to indicate that if I have radials that are parallel to each other the performance of the overall systems will degrade; one solution he offers is to use 1/8 radials instead of 1/4.
BTW, listening to a few guys on 80m and a single station on 160 seem to produce audible F/B as I switch directions.
Rudy N2WQFrom: 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, 7:28:38 PM EDTSubject: Re: [TowerTalk] Tuning raised radial verticals

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 myqrz.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 atwww.contesting.com under n0ah in 1999, 2000

GL

73 de paul N0AH

DXengineering sells them.

73

paul. N0AH

73   

Sent with AquaMail for Android
http://www.aqua-mail.com

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 N2WQFrom: 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 EDTSubject: 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.....

Sent with AquaMail for Android
http://www.aqua-mail.com


On August 31, 2017 12:23:04 PM Rudy Bakalov via TowerTalk 
<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
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk