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Re: Topband: 160m Vertical matching Help

To: Ronald Gorski <R.Gorski@Astronautics.com>, MR TREVOR DUNNE <ei2glb@eircom.net>, "Wes Attaway (N5WA)" <wesattaway@bellsouth.net>
Subject: Re: Topband: 160m Vertical matching Help
From: vk2wf <vk2wf@bigpond.com>
Date: Fri, 03 Nov 2017 11:16:53 +1100
List-post: <mailto:topband@contesting.com>
In my experience the vertical with its top loading etc. Needs to be resonant at 
2.1 Mhz. Then a 50 ohm match will be easily achieved with just a few turns from 
the bottom. I tried it first with the vertical resonant at 2.001 Mhz then I 
found that the impedance tapping point did also influence the resonant 
frequency of the antenna.73Adrian VK2WF


Sent from my SAMSUNG Galaxy S7 on the Telstra Mobile Network
-------- Original message --------From: Ronald Gorski 
<R.Gorski@Astronautics.com> Date: 2/11/17  5:37 am  (GMT+10:00) To: MR TREVOR 
DUNNE <ei2glb@eircom.net>, "Wes Attaway (N5WA)" <wesattaway@bellsouth.net> Cc: 
topband List <topband@contesting.com> Subject: Re: Topband: 160m Vertical 
matching Help 
Trevol, the portion of the coil between the tap and the base of the vertical 
determines resonance and needs to be variable unless you were lucky and found 
the correct value. The shunt portion of the coil affects the feed impedance. 
This shunt portion is like the hairpin match for a yagi. You select the series 
inductance to make the antenna slightly capacitive and adjust the shunt 
inductance to raise the feed impedance.  Both these moves interact. Use a clip 
lead to vary the inductance of the series coil.
Cheers,
Ron N9AU 

-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of MR TREVOR 
DUNNE
Sent: Wednesday, November 01, 2017 12:12 PM
To: Wes Attaway (N5WA)
Cc: topband List
Subject: Re: Topband: 160m Vertical matching Help

Hi Wes

Thanks for the reply I can move the point of lowest SWR by moving the tap on 
the coil, I need to lower the SWR I thought using the coil across the feed 
point would do this but its not working for me??

Thanks
Trevor
EI2GLB

----- Original Message -----
From: "Wes Attaway (N5WA)" <wesattaway@bellsouth.net>
To: "MR TREVOR DUNNE" <ei2glb@eircom.net>, "topband List" 
<topband@contesting.com>
Sent: Wednesday, 1 November, 2017 17:02:55
Subject: RE: Topband: 160m Vertical matching Help

Without doing any modeling, an off the top of the head idea, one option would 
be to drop a wire down from the end of each of the T wires you have at the 
top.  You might be able to move the point of lowest SWR down to 1.8 with 2x 15' 
+/- drop wires.

   -------------------
Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
AttawayForensics.com
   -------------------
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of MR TREVOR 
DUNNE
Sent: Wednesday, November 01, 2017 11:54 AM
To: topband List
Subject: Topband: 160m Vertical matching Help


Hi All



I finally got the vertical up and running, problem I have now is I can't find a 
low SWR on the coil, the best I can get is about 2.8:1 no matter where I tap 
the coil that's the best SWR, I can move that point up and down the band by 
moving the tap but the SWR stays the same,

My current set up is about 55ft vertical I have 2 loading wires in a T shape, 
wires are 50ft either side of the vertical and the are pretty level and in line,

I have 38 radials averaging about 45-60ft long, I will add more when time 
allows but don't the make the SWR worse ??

With no coil I get resonance at 2.12mhz with R=16 X=2 on my MFJ269,

The coil is 25ft of 5mm copper brake pipe in a 4" diameter, the coil is 
attached to base of the vertical and the other end is grounded,

Any pointers on what I can do to get a better match,

Thanks
Trevor
EI2GLB
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