Boom matching as a rotary dipole on 30 and 40M works VERY WELL.
I have used a matched 24 ft boom on a TH6 on both 30 and 40M
(separately).
It 'should' be possible to use two matching arms, one for 30M and
the other for 40M (be SURE to disconnect the unused feedline from
any radios to prevent burning out the RX front end).
Another TowerTalk subscriber used stepper motors to drive
variable capacitors for his matching unit and was able to get
enough range to tune BOTH 30 and 40M.
Tom N4KG
On Fri, 25 Oct 2002 07:29:09 EDT SavageBR@aol.com writes:
> Dave I don't know what else you might have in the air. If you have 20
> M
> monobander or tribander you might try Gamma matching the boom on
> either 30 or
> 40 M and see how close the match is on the other band. This approach
> for 40 M
> has been perfected over the years by Tom, N4KG and others using
> various
> beams.
>
> I am using a boom matched 204BA monobander (4 el 20 M Yagi) at 74
> ft, matched
> for 40 M (see QST, August 1983). However, it also works very well on
> 30 M
> with an SWR of about 3:1. At 200 watts max, the 3:1 is no problem.
> The 40 M
> performance is very good. The 30 M performance is similar to my D3W
> at 50 ft.
>
> Good luck,
> Bruce AA4Z
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