[TowerTalk] dipole length adjustment

[Jim Lux]

At 04:15 PM 1/21/2007, W2RU - Bud Hippisley wrote:
>Cecil Moore wrote:
>
> >> From: W2RU - Bud Hippisley <W2RU at frontiernet.net>
> >> Subject: Re: [TowerTalk] dipole length adjustment
> >> What's simple about getting up from the rig, walking to the coat closet,
> >> getting my coat and hat and boots and mittens, going outside to my tuner
> >> that's located at the feedpoint of my antenna, turning the knobs in -20
> >> degree weather, and returning to the house where I go through the
> >> reverse process, only to find the DX that I was going to chase has
> >> disappeared?
> >
> >
> > Point is, you don't have to do that with an SG-230.
>
>
>Point is, I can't find an SG-230 that runs 1500 watts.


Bud makes an interesting point here.  Certainly, for 100-200W, it's 
pretty easy to find a reasonably low loss auto or remote tuner so the 
"coax/tuner at feedpoint/easy routing of coax" alternative is 
competitive with the "tuner at transmitter/openwire line/a bit more 
pain to route" approach.

But at 1500W, there aren't so many alternatives.  1500W automatic or 
remote tuners are going to be bigger and bulkier (and, so, a bit 
trickier to install at the feedpoint), so the system tradeoff might 
be more competitive for the openwire line approach.

For instance, you could take the existing tuner Bud is using, put it 
in a weather proof enclosure, add some servos or steppers, etc.  But 
that's probably more of a pain than just running the openwire line.

It might well be, though, that as time goes on and technology 
improves, it will get easier to put the adjustable matching network 
at the feedpoint, assuming there's a reasonable demand.

Speaking to the latter, I doubt there's a whole lot of people running 
a kilowatt to an untuned low loss, low gain antenna (at least ones 
who'd be willing to pay the few thousand dollars a well integrated 
system with coax feed).  The system designs if you positively have to 
have coax feed probably tend to look like full custom (i.e. not an 
off the shelf product) or some sort of lossy broadband radiator (like 
the B&W loaded folded dipole)

Jim, W6RMK