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Re: [TowerTalk] 80 Meter beam

To: Grant Saviers <grants2@pacbell.net>
Subject: Re: [TowerTalk] 80 Meter beam
From: Kelly Taylor <ve4xt@mymts.net>
Date: Fri, 31 Mar 2017 09:42:22 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Here’s a thought: if one can use a fan dipole to make an inverted vee cover 
both 80 and 75, how about a fan reflector?

73, kelly, ve4xt 


> On Mar 31, 2017, at 9:30 AM, Grant Saviers <grants2@pacbell.net> wrote:
> 
> I think you need to model what you are attempting.   You don't mention the 
> antenna support and if it is a tower then there is a fair amount of 
> interaction with the V.  However, a 39' boom will help if the tower is at the 
> midpoint.  I've modeled a number of phased 80m delta loops on a 89' tower and 
> you might consider delta loops vs an inv. V.  With a 120' support and a 39' 
> boom you've got a good start for a great antenna.
> 
> For it to perform as a parasitic beam on two frequencies, then the inductance 
> needs to be added to both elements.  Using a tuner to get acceptable swr 
> doesn't change the pattern, which may even reverse from what you want. Cut 
> for SSB and add feedpoint inductance for CW and perhaps have two values of L 
> to cover most of 3500 to 3840 or so.  PVC junction boxes on the boom ends 
> with relays for switching. This is how my 2L JKantenna beam covers 3500 to 
> 3840.
> 
> Another (and probably better) choice is to drive the two V or loop elements 
> out of phase to create the pattern.  You may find a design that has enough 
> swr bandwidth for SSB and CW.  Optimize the (switched) phasing lengths for 
> pattern since swr coax losses are low on 80m and your tuner can make the amp 
> happy.  A quick mod of my phased loop model says this may work.
> 
> check out
> 
> http://www.transduction.com/PDV.pdf
> 
> and W8WWV's work on 80m V 
> http://www.seed-solutions.com/gregordy/Amateur%20Radio/Experimentation/IVee80.htm
> 
> there is also a lengthy blog like tale of phasing two V's on a tower (gave up 
> after 3 years) but I can't find it now, perhaps other TT'ers have the link.
> 
> Grant KZ1W
> 
> 
> 
> On 3/31/2017 5:00 AM, Martin Pelt wrote:
>> I am putting a 80 meter 2 element inverted vee beam up. It will be at 120
>> feet with 39 foot boom.
>> 
>> I have 2 questions dealing with switching from phone to cw without lowering
>> elements and using jumpers.
>> 
>> I plan to use ladder line on driven element coming down to tuner to switch
>> from cw/ssb. Will this work or is there a better way ?
>> 
>> On the reflector I thought maybe cutting it for ssb the having inductor
>> with relay at the center to switch to CW. Is this the best way ? If so how
>> can I easily measure resonate frequency with inductor inserted at the
>> center ?
>> 
>> 73 Martin N4UU
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>> 
>> 
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