Glenn,
Taking up Larry's suggestion even further, put one gamma match along the
boom in the reflector direction for 40mx (usually right to the reflector)
and another gamma match along the boom in the director direction for 30mx -
usually about half the distance to the director.
You probably need to use an omega match (2 variable capacitors) rather than
a gamma match, for ease of adjustment.
Have been using that system for years with almost every country worked on
both bands.
Cheers
Peter VK3QI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Larry
K4AB
Sent: Wednesday, 5 March 2014 7:28 AM
To: Glenn Pritchard
Cc: Tower and HF antenna construction topics.
Subject: Re: [TowerTalk] TH7dx with 40 meters
Why not gamma-match the boom of the TH-7 as a rotary dipole for 40?
Check the archives, or the NCJ archives for the details.
Works great!
73,
Larry K4AB
On Tue, Mar 4, 2014 at 1:57 PM, Glenn Pritchard <hfcomnet@gmail.com> wrote:
> Hello gang,
>
> Has anyone thought of adding a set of 20 meter traps to the driven
> element of a th7 to add 40 meters?
> If so which traps, th5 or th6?
>
> I have been thinking of this and putting the traps on the first driven
> element then experimenting with the length.
>
> This would give me a rotatable dipole on 40.
>
> My first idea was to put a 40 meter two element Yagi on the th7 boom
> and adding additional struts.
>
> Any thoughts?
>
> Glenn, VE6ND
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