Hi Alex
I also have an A270-10S but have been fairly pleased with the antenna.
Now, I agree, it not an antenna for serious VHF/UHF work. I use it in my
rover station.
I've also run some basic test to see what the pattern would look like and
found the pattern fairly consistent with the EZ-NEC model of the antenna.
Per the model, it's a better antenna on 2M than 432.
Interestingly, if you reversed the coax from the duplexor to the driven
elements, you will get the pattern you described on 432. SWR would be a
bit high but not too bad. However if you reversed the 2M coax (connected
to 432 DE) you would get a very high SWR. I have to wonder if your
duplexor was faulty although I can't come up with anything that would give
you a cardioid pattern on 2M.
73,
Tom K6EU
On Wed, Apr 16, 2014 at 6:17 PM, Alex <alex@kr1st.com> wrote:
> Hi John,
>
> I bought two A270-10S antennas with a phasing harness from a fellow ham. I
> put the stack at 30 feet (horizontally of course) and did some experiments.
> I found that the performance was very disappointing on both bands . A
> simple
> 4 stack of halos at the same height would outperform the stacked beams on
> 70cm. It was marginally better than a single stack of halos at the same
> height on 2 meters. The feed line lengths were the same on all antennas,
> except that the halos were fed with RG-8x and the beam was fed by the
> Wireman's LMR-400 equivalent...
>
> Then I decided to try a single beam and had someone a few miles down the
> road send a test signal while I rotated the antenna to get an idea of what
> the azimuthal pattern was. It turned out to be a sort of deformed cardioid
> pattern, barely directional, and the direction of maximum gain was about 30
> degrees off. The pattern was similar on both 2 and 70 cm. My conclusion was
> that these antennas were useless for weak signal SSB or CW.
>
> Think about it. How often do you hear the question being asked about the
> optimal vertical distance between a 2 and 70cm beam. I don't think anyone
> ever answered "zero" to that question.
>
> 73,
> --Alex KR1ST
>
> -----Original Message-----
> From: VHFcontesting [mailto:vhfcontesting-bounces@contesting.com] On
> Behalf
> Of John Geiger
> Sent: Monday, April 14, 2014 3:55 PM
> To: vhf contesting; vhf@w6yx.stanford.edu; 50mhz; 6meter@yahoogroups.com
> Subject: [VHFcontesting] Cushcraft A270-10S (triband VHF/UHF) beam question
>
> I have a question about the Cushcraft 6m/2m/70cm yagi. Every picture I see
> of it has the 6m elements horizontal and the 2m/70cm portion vertical. That
> wouldn't work for me, I want to use it on 2m and 70cm SSB. It is possible
> to
> mount all 3 bands with horizontal elements?
>
> It looks like it is physically possible, but will it hurt performance, or
> will it still work ok that way?
>
> John AF5CC
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