Correction, 70' radial and 68.5' element. Good catch!
Rudy N2WQ
On Friday, September 1, 2017, 10:16:24 AM EDT, Bryon Paul Veal NØAH
<bryonveal@msn.com> wrote:
guys, is it jist me or do these antennas sound to long to begin with? Array
resonant aside...
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On August 31, 2017 5:45:49 PM Rudy Bakalov <r_bakalov@yahoo.com> wrote:
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@msn.com>To: Rudy Bakalov
<r_bakalov@yahoo.com>; Towertalk Reflector <towertalk@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 at
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@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@msn.com>To: Rudy Bakalov
<r_bakalov@yahoo.com>; Towertalk Reflector <towertalk@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.....
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On August 31, 2017 12:23:04 PM Rudy Bakalov via TowerTalk
<towertalk@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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