[amsat-bb] 1268 Helix W7LRD Antenna
john at papays.com
Tue Sep 1 10:16:01 PDT 2009
My 1268 setup is a W7LRD 13 turn helix fed
with a 9' 9913 jumper, 45' of 7/8" Heliax and
a 3' Superflex jumper to the TS2000X.
Ten watts is just about right for this setup.
Reducing power to 5 watts makes a very noticeable
difference; readable but noisy. One watt works
when the bird is overhead but noisy.
Bob makes a longer Helix which I would recommend
for the extra gain without making the antenna very
much bigger. We did use this antenna at field day
and made a L/U contact with it. A picture of the
antenna at our field day location is on the ARRL
Contest Soapbox. Go to arrl.org, Operating Activities,
Contests, Soapbox, select ARRL FD 2009, and then search
on W8DXA or K8YSE. There is a closeup of the antenna
in one of the photos. The antenna uses aluminum,
stainless and copper and is well built. It should
have a long life. I understand Bob is working on a
radome for it which will make things a lot better for
those of us who live where we get snow and ice.
You can also see the setup on my 30' tower on the qrz.com
page. Click on the image to make it bigger. The 2.4
panel antenna is also visible.
The doppler is significant at 1268 so doing it with a
handheld and a long antenna would be a challenge. It
would be a lot easier to operate with a marginal signal
if it wasn't for the radar interference which is present
on all but the very strongest signals. You can listen
to the 435.150 output and get a good idea of what things
sound like. If you already have a radio with 1.2Ghz
transmit, the antenna, whether you build or buy, won't
be much of an additional cost.
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