[Towertalk] I need to be louder on 40 and 80.

Don Havlicek n8de@thepoint.net
Thu, 28 Mar 2002 07:18:27 -0500

Comments inserted below:

Chris Hurlbut wrote:
> Hi everyone,
> Maybe some of you can help me out.  I'm looking to improve the 40 and 80
> meter signal here at the University of Idaho, W7UQ.  Right now the antenna
> is a ladder line fed inverted vee wire of unknown origin, up about 50 feet
> on the side of a wood chip silo.  I've been thinking up ideas, but I'm not
> really sure what would work out best.  Maybe some of you out there have
> experience with one or more of these and could help me out.  Here is what we
> have here at W7UQ:
> On top of the powerplant on campus is our tower with a TH7 on top.  I am
> guessing the tower starts at 50 feet, and is 50 feet tall.  This puts the
> TH7 at about 100 feet.  There isn't much room to stretch out wires or
> anything on top of the tower that would go out.... but something might be
> worked out with the powerplant people.  Just below the TH7 is a random wire
> that seems to be worthless, but it is very large.  I've never used this
> antenna effectively on any band.  My goal is to be loud for DOMESTIC
> contests... such as NAQP, SS, and the sprints.  Very rarely would I ever do
> a DX Contest seriously from here.  There is limited space, but a wire
> pointed east/west is doable (ie dipole, etc).
> I have had a few suggestions already about what might work, but I'm not sure
> if some of them would be worth the trouble.  On the other hand, they may
> turn out to be great.  Here is what I have thought up, or people have
> suggested:
> 1) Loading the tower for 80 meters, and hanging radials off the side of the
> silo.  Sounds like a great idea to me, just not sure if the powerplant folks
> would go for it.  Would it be THAT much better than a dipole?  What about
> effectiveness in a domestic contest setting?  Would it work at all with 50
> feet of tower and a tribander?  Hanging radials?

This should be your LAST choice .. you want domestic QSO's .. the prime
angles of radiation from this antenna would be better for DX.
> 2) Loading the guy wires as a sloper array if they're long enough, shorting
> at the breaks in them.  Not sure how this would work, but it sounds cool.

This would work .. but be very time consuming .. and possibly dangerous,
as it would require removing the guy wires and replacing them .. not a
good choice.

> 3) Dipole on each of 40 and 80, up as high as I could get them.  (Seems like
> the best to me?)

Second best in my mind .. would you be using them in a horizontal dipole
fashion or as 'inverted-V'?  If the latter, then there will be some
tuning/bandwidth problems depending on proximity to the tower.

> 4) Other wire type inverted vee array such as a double extended zepp.  Maybe
> it has more gain than a dipole?
This is TWO choices:  Inverted-V [usually dipoles with low ends-see my
comments above] or the Double-extended Zepp [my FIRST choice-provided
you can elevate the ends].  

> 5) HF2V butternut vertical.  We have one of these in the shack + coax ready
> to go up.  Aren't they supposed to be ground mounted with a ton of radials?
> Not sure we could get it on the ground, or up in the air with enough wire
> for it to work.

Another LOW ANGLE radiator .. better for DX than domestic QSO's.

> 6) 2 element 40m yagi fixed to states (I WISH! heh)  But maybe a wire yagi
> with close spacing?  It would have to be pretty close spacing... no more
> than about 12 feet I think, if that much.

Seems like you'd have a difficult time working the Southern California
area as well as the East Coast on this array.  Each is off the side of
the other.
> I really like the idea of the tower turned into a vertical, but I'm not sure
> if hanging radials would even work?  I'm no antenna expert.  Dipoles seem to
> work OK, at least better than some non-resonant wire.

As I said above, for domestic contacts, you want something which will
radiate at high angles efficiently .. for 40 & 80 meters, I'd choose the
double-extended Zepp .. IF you mount it relatively horizontally ..
second choice would be the high dipole .. or inverted-V .. last choice
would be any vertical array.  Not sure you'd want all the directivity of
the wire-beam.

Just my thoughts!
Don - N8DE
> Any help would be appreciated, and it might even get you an extra mult in
> NAQP :)
> Thanks,
> Chris KL9A
> kl9a@qsl.net
> http://www.qsl.net/kl9a
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