I just went back to look at the WA5VJB cheap yagis. They are specifically
designed to be easy to build from readily available materials - wood booms
if you want.
HF guys tend to be even cheaper than VHF guys if such can be imagined. If it
costs them more than a few dollars to try a new band they are likely not to
try. So that is the reason for mentioning the Cheap Yagis. If you want to
pay more money you can send Mike Staal or Dave Olean your dollars and they
will provide you with an excellent antenna that will work. If you just want
to try something you can do the Cheap Yagi or one of the other designs
Duffey mentions.
No fancy test equipment is needed. Just carefully repeating what Kent tells
you are the dimensions. For that matter a good HF SWR meter will almost
always work as a directional coupler on 6 meters [all the kw swr bridges do
that very well] and probably will be servicable on 2 meters though I haven't
tried this - power output readings will be inaccurate on 2 but swr readings
won't be off by that much I believe.
I don't recommend it but I believe the 706 is protected against running into
an open [no antenna] and probably a short as well [somebody check me on this
if I am incorrect - mine never blew up but as I said I DON'T RECOMMEND DOING
THIS]. The amplifier has a fold back circuit that shuts down the 706 final
to a very low output. So anything below a 2:1 SWR probably won't do any
damage.
What about six meters if you already have an HF station? You can get a
servicable antenna from your 40 meter dipole. For close in work it is better
if the dipole is horizontal rather than a sloper or a vertical but for Es it
doesn't matter. A 40 meter dipole will operate like 7 half waves in phase on
6 meters and usually with a low enough SWR that you do not need a tuner.
There will be peaks and nulls but hey - it takes power and works people. If
you like what you hear you can always buy or build a real beam. But give
yourself a chance - do this either during some kind of contest or between
the months of mid-May to mid-July so you have a chance to encounter some E
skip. [In case you have a 160 meter antenna, it will probably work on 6 as
well though the comments about horizontal vs vertical apply here too].
73 Gene W3ZZ
-----Original Message-----
From: James Duffey [mailto:jamesduffey@comcast.net]
Sent: Wednesday, March 03, 2010 7:13 PM
To: VHF Contesting Reflector
Cc: James Duffey
Subject: [VHFcontesting] Getting beginners interested in VHF Contesting
Hey Eric - Nice to hear from you on this topic. I was not advocating that
everybody operate with all homebrew equipment.
Nothing wrong with commercial antennas, in fact I have a Cushcraft 13B2 that
I rove with on occasion. It was given to me. I just like to build my own
antennas, and show other people how to build their own. Up to 432 MHz at
least, there are several good beam designs that work well as built with no
testing or tuning required, nor special tools or instruments, just careful
measurements. Sure you can tweak a bit more out of them with a bit of test
gear, or build antennas with slightly higher gain with some testing and
tuning, but for the beginner, better is enemy of good enough. The simple
designs should be enough to get them on the air quickly, cheaply and get
them hooked.
I have given several talks on VHF contesting and roving over the past year
and a half. I always take a few antennas to show and people are always
amazed that simple homebrew antennas like the WA5VJB designs are available
and work well. I always get comments when I show the WA5VJB antennas like,
is that all there is to it? And hey, I can build that. My favorite: Does
that work as well as an Arrow? The guy with the 706/7000/FT100 or whatever
usually uses it on 2M and 70cm FM and that is it. If we can get those guys
on the weak signal modes, which the simple homebrew antennas they can do
without much investment, then we can hook some new blood into contesting.
Even getting the 706 guys who use loops to switch to beams would help a lot.
But getting guys on loops from verticals is a big step, if they do it for a
contest.
At 6M, the N2MH version of the Moxon is easy to build from common materials
and is a great performer compared to the loop or dipole that the guy may
have been using. Again just careful lmeasurements are required and pretty
much all the parts can be purchased locally.
I like the notion of distance scoring used in at least one contest and I
think that if a guy uses computer logging, like Roverlog, the distances are
calculated and scores calculated with no additional input from the user, so
it really isn't any more complicated. The Spring Sprints will use distance
scoring so we can all see what that is like.
For those on the list that hadn't noticed yet, Eric has one of the greatest
calls for VHF contesting there is. He is also one of the premier rovers in
the Rocky Mountain Division and does a bang up job on 10 bands from that
many or more grids, even in January. - Duffey
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