[amsat-bb] Re: cross boom?
Michael A. Tondee
mat_62 at netcommander.com
Fri Apr 4 22:03:30 PST 2008
I went with the choice of a non metallic crossboom because originally I had
planned to build CP antennas and thought it would be the best option. As it
turned out, I decided against CP antennas at present because I didn't have
the measuring equipment to properly determine the velocity factor of the
coax used in the phasing harneses. I probably will eventually construct CP
antennas, I even have a second set of aluminum rod elements for the 70 cm
antenna,but I just decided to simplify things to start with.
----- Original Message -----
From: "Edward Cole" <kl7uw at acsalaska.net>
To: "Michael A. Tondee" <mat_62 at netcommander.com>; <amsat-bb at AMSAT.Org>
Sent: Saturday, April 05, 2008 12:50 AM
Subject: Re: [amsat-bb] Re: cross boom?
> If you are using linearly polarized yagis, just mount each vertical and
> separate horizontally about 5-6 feet using an aluminum crossboom. There
> is no need for non-metallic boom if the crossboom is perpendicular to the
> plane of polarization. Ideally, the separation would be so that the field
> of neither antenna were to touch, but practical separation of the field of
> the higher frequency antenna is sufficient. If you get cross-talk between
> VHF and UHF it may be and advantage to have one antenna place in the
> opposite polarization. Then mount each on a 45-degree slant \-----/
> I use two x-yagis mounte on metallic crossboom. The antennas are mounted
> in an X----X configuration and both are RHCP with no problem of cross-talk
> using up to 50w. Preamps are used with both antennas so either mode-UV or
> VU may be used. My crossboom is about 6-foot long and both antennas have
> about 18-foot booms.
> 73 Ed - KL7UW
> for pictures
> At 06:38 PM 4/4/2008, Michael A. Tondee wrote:
>>I used schedule 80 PVC with a large wooden dowel pushed inside for added
>>rigidity. I sealed each end with epoxy. It's been going strong for a
>>of years now. I saw your other post about antennas. At present I'm using a
>>four element 2 meter beam and an 11 element 70cm beam in vertical
>>polarization. Both are homebrewed using Ken Britain's "cheap yagi"
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