This is good stuff. Thanks for sharing.
73, Bob K0NR
On 16-Feb-18 10:53 AM, David Olean wrote:
More data....
We ran a similar test using a rover station 4 element 50 MHz yagi at
12-14 ft vs a halo at 35 ft. This was a real test and not a quick
exchange during a contest. The path was about 280 miles long and the
halo was a definite winner over the low yagi for the rover station. A
home station was on the other end of the path. The rover was W2GE/r
with N2CEI and WB2ONA at the Packrat contest location in the Poconos
in FN21. I was operating the home station in FN43 in Maine. Height
above ground makes all the difference on 50 MHz.
Dave K1WHS
On 2/16/2018 5:07 PM, Bill Olson wrote:
Hi all, This might be a good time to bring up "height above average
terrain" for a 6 meter beam. I'll digress here a little then will get
back to the point. I used to rove with the lower 6 bands. Antennas
were all mounted on a rotor fixed to roof racks on my truck. There
were ~ 8 ft yagis and loop Yagis on 2 thru 1296 BUT on 6 meters I had
an old 4 element Yagi on a 12 foot boom. This got mounted right above
the rotor so was maybe 7 feet off the ground. (Yeah the ~9-10ft long
6M elements hung over the sides of the vehicle a little - never was a
problem with law enforcement hi). Everything worked great except 6M.
It had reasonable SWR and I knew the Yagi worked because I had used
it on the tower.. but signals were weak except when the band opened
for e-skip.. Well that should have tipped me off right there but It
wasn't until I had a talk with Pete, K9PW, who used to operate with
the AA9D multi-multi VHF contest station in central Illinois. They
had done some experiments with
their rovers and found that just a HALO antenna at 25 feet WAY out
performed a multi-element Yagi at 10 feet.. Well duh, of course the
Yagi's pattern in the vertical plane got more and more elevated off
the horizon the closer it got to the ground and at 10 feet there was
practically no response on the horizon. I haven't done any of the
math BUT just experimenting with it, I arrived at about 20 feet for
my rover 6M antenna. I built a 2 element beam on a four foot boom.
This could easily ride on the roof racks with the elements pointing
fore and aft. I put together a 20 foot mast and that got stowed up
there too.. So, yeah, no operating 6m while in motion, but with a
trailer hitch sort of mount for the mast, it really only took a
couple minutes to get the 6M beam in place.. Armstrong rotated for
me, but here in Maine pretty much everyone is in the same direction
and with abroad pattern it was pretty much set it and forget it.. The
results were quite amazing and all of a sudde
n I worked stations on tropo at several hundred miles..
To get back to the back-packer antennas, folding up the antenna and
making it "packable" is one thing but then you need a 20 foot mast
too and a way to keep it up in those high mountaintop winds!! The
gain of the antenna is not doing you any good if it's peak is above
the horizon and there is a null AT the horizon!
just saying..
bill, k1DY in Maine
________________________________
From: VHFcontesting <vhfcontesting-bounces@contesting.com> on behalf
of Mark Spencer <mark@alignedsolutions.com>
Sent: Thursday, February 15, 2018 4:22 PM
To: Bob K0NR - email list
Cc: vhfcontesting@contesting.com
Subject: Re: [VHFcontesting] Portable 50 MHz beam antennas
Thanks All. I got some great on and off list responses.
Yes I believe the 40" length limit is a reasonable one. (I have
found carrying 48" mast sections via backpack to be a bit awkward for
me.)
73
Mark S
VE7AFZ
Aligned Solutions Co.
mark@alignedsolutions.com
604 762 4099
On Feb 15, 2018, at 7:17 AM, Bob K0NR - email list <list@k0nr.com>
wrote:
Zack,
I'd be interested in the 144 MHz yagi design for backpack portable
operating.
Its got to be compact and easy to assemble, otherwise it tends to
get left at home.
For me, compact is nothing longer than 40 inches.
(I'm actually thinking SOTA more than VHF contesting but I sometimes
combine the two.)
73, Bob K0NR
On 15-Feb-18 7:57 AM, Zack Widup wrote:
I got a design from VE3BFM for a four-element 6m beam on a 13 foot
boom.
It's a great performer. Since I operate portable 95% of the time, I
built a
version I could quickly assemble and disassemble at a portable
site. The
boom and each element is in two pieces. I never formally wrote up an
article about how to build it, but I did talk about it at the VHF
forum at
Dayton a couple years ago. Maybe I should write it up.
I have similar portable Yagis for 144 through 432 MHz. I can
assemble and
disassemble them pretty quickly. My 144 MHz Yagi has six elements
wide-spaced on a 12 foot boom. I believe the gain predicted by Yagi
Optimizer is about 12 dBd. I haven't measured it yet.
73, Zack W9SZ
On Thu, Feb 15, 2018 at 8:23 AM, jon jones <n0jk@hotmail.com> wrote:
Mark:
Another idea is to build your own portable 6 meter beam. I have
found a 2
element yagi is easy to build, break down and re-assemble quickly.
A 2
element yagi offers about 3 - 4 dB gain over a dipole. It is
easier to put
up and take down than a 3 el.
I use one for my VHF contest and portable operations. A picture of
it is
in the NCJ March/April 2016 pp. 32. It works... have WAC with it
on 6 with
100 W from KS on ssb/cw.
A plan for one is here: http://www.qsl.net/k7yo/6m2Yagi.htm
[http://www.qsl.net/k7yo/6m2yagi.jpg]<http://www.qsl.net/k7yo/6m2Yagi.htm>
6 meter 2 element yagi - QSL.net<http://www.qsl.net/k7yo/6m2Yagi.htm>
www.qsl.net
6 meter, 2 element yagi. A simple, compact and effective antenna for
50 Mhz. This antenna was built in about an hour after using K6STI's
AO simulation ...
- Jon N0JK
________________________________
Hi:
I finally took delivery of a suitable LiPo battery to facilitate
"back
pack portable" operation at the 50 to 100 watt level. If any of my
Canadian colleagues are interested I can provide the contact
details for a
Canadian distributor.
At this point I'm planning on simply taking my 50 MHz three
element beam
apart and re assembling it on site. In my view the beam I have
isn't
really intended for that type of use and I'm curious if anyone
knows of any
suppliers for small 50 MHz beams that break down and re assemble
quickly
and easily. Google searching on my part didn't turn up anything
that is
currently in production.
I'm hoping to shift my focus a bit this year and actually reach
the true
summit of at least one local mountain (vs simply driving most of
the way up
via logging roads.) Having this ability would also have been useful
earlier this year when I had to abort my CO81 visit during the sept
contest. In hindsight I suspect I could have activated the grid
for a few
hours on foot.
73
Mark S
Aligned Solutions Co.
mark@alignedsolutions.com
604 762 4099
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