Pertinent comments by James re. the Moxon vs. a loop antenna for Rover or
portable operation. 4 - 5 dB gain over a loop may not sound like a lot... but
it is significant. It will make the difference between calling CQ with no
replies and running stations during openings. Hearing a weak DX station vs.
putting them in your log. I have worked James when he was rover/portable in New
Mexico on Es and he had a great signal on 6.
Another option for a rover operating fixed or a portable station on 6 meters is
the 2 el yagi. I use one for my rover and portable operation. It has about the
same gain as a Moxon, and my the only costs were the coax. I can put it up in
less than 5 minutes and it breaks down and fits easily into a Hyuandai Elentra.
The coax connects directly to the front driven element - no gamma match needed,
and the SWR is almost a flat 1:1 at 50.125. I use Radio Shack 5 ft. TV masts.
A horizontal antenna will work much better on 6 if you can get it up at least 1
wavelength (18 feet) high. 15 feet is a reasonable compromise, 20 ft. is
better. I also use a 3 el M2 yagi for portable use, but it takes a lot longer
to put it together and it is more cumbersome to put up. The 2 el is my choice
for "pop up" fixed Rover operating and getting on the air quickly at a rest
stop or high point. While DX results vary on conditions -- I have worked all
continents on 6 with the 2 el yagi via Es includin
g JW7QIA near the north pole from Kansas since 2006.
A plan for building a 2 element 6 meter yagi here:
http://www.qsl.net/k7yo/6m2yagi.htm
The Moxon or 2 el yagi are also good options for a 6 meter attic antenna.
- Jon N0JK
> The Moxon is an excellent performer compared to a loop. It particularly
> shines during marginal band openings, when the band is just opening and when
> it is closing. Compared to a loop, it is much easier to hold a run frequency
> and to attract the attention of strong stations who may not have their
> antennas pointed towards you. At 4 dB gain over a dipole, it is probably 5
> or 6 dB gain over a loop, and that makes a big difference, particularly when
> signals are near the noise level. If you are running a loop and want to make
> a big improvement to your rover, go to a Moxon. The cost of the PAR SM-50,
> which was $100 when I bought it, and I think now is close to $120 with the
> rise in Al prices. That price is about the same, or not much more than a
> loop, I see HRO is selling the M2 6M loop for $140, but the results from the
> Moxon are much better than a loop.
>
> At 7 ft wide and 31 inches deep, it is a big antenna, but the wire reflector
> and 5/16 inch side pieces make it fairly light weight. You need to plan for
> it in the installation. I use 1.25 inch EMT for a mast and that is more than
> adequate, even with 8 ft antennas for the other bands installed. We drive
> with it at 10 to 12 feet high and extend it to 15 feet or so when stopped.
> When I first got the antenna and put it together in the driveway prior to
> roving, my first thought was ?This is a big antenna?. About that time
> Virginia came out of the house looked at the Moxon and said ?That is a big
> antenna. You?re not going to drive with that on the car are you?? I
> answered, ?No, you are.? After initial test runs at lower speeds, we
> concluded that cruising at 75 mph with it on the car was not a problem. With
> the additional wind loading the gas mileage suffers though.
>
> If you are into SOTA or portable operation, the Moxon breaks down nicely into
> a 3 ft long package about 2 inches in diameter and assembles quickly.
>
> Dale provides excellent support for the antenna and has shipped me side
> pieces on short notice. No balun is included so you probably should add one,
> a string of ferrite beads do nicely, and, in case you are wondering, and
> everyone does, there is nothing magic in that black box except wires
> connecting the driven element to the SO-239.
>
>
> James Duffey KK6MC
> Cedar Crest NM
>
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|