[Towertalk] Re: 40 meter boom, 80 meter dipole?

[Jan Erik Holm]

I think N4KG would have a lot of info on this, however I think
it will work just fine.
One example. I have a 20/15 duobander 4 el 20 and 5 el 15
on about 38 ft boom. Was going to tune it for 40m but since
it had a lot of loading from those 9 elements it ended up on
80m (huuh). The thing is only at 70 ft so it doesnt work very
good except for local QSO´s but it´s an antenna that can be
used.
I used Omega match and replaced half of the boom guy with
parafile/phillystran and did keep the steelwire on the other half
and used that as a gamma rod, used RG-213 for capacitors,
I have tested it with very high power and it´s no problem.

73 Jim SM2EKM
------------------------------------------------------------

Paul Young wrote:

>I have a three element 40 meter beam.  I'm thinking about
>matching the boom as an 80 meter short dipole.
>
>The boom length is 48'.  The driven element is insulated but
>the parasitic elements are connected to the boom.  They are
>full size and provide plenty of end loading.  It has a T-bar
>truss which is not insulated but I don't think I would want
>to use it to feed the antenna.
>
>The problem, of course, is feeding it.  Tilting the antenna
>is difficult, but I figure I can tip it once and install
>some sort of omega rod.  Then I can tune it from the mast.
>The bandwidth may be narrow enough that I'll need to put up
>a relay to switch it to phone.
>
>Has anyone tried this?  What sort of omega rod will I need?
>Any caveats?
>
>                           Paul, K1XM
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