On Tue, 25 Mar 2008 09:32:51 -0700, Jim Lux
wrote:

Buck wrote:


Now that auto-tuners are about as inexpensive as the manual tuners, I
am awfully tempted to wander over to the SGC shelf at one of the ham
stores and try it out.

I am moving to a new house soon. We will be restricted in antennas
only to the extent that we don't make the yard look too ugly. It
isn't terribly well suited for many antennas, but I do hope to put up
at least one decent fan-dipole, more accurately parallel dipole. I
don't think I can fit a full-wave loop, due to lack of supports, but
it looks like I'll have a place outside my window where a row of trees
can support a 60 foot or so high dipole.... I still have a 100 foot
roll of 300 or 450 ohm window line


The advantage of the tuner with a "fan" or "parallel wire" dipole is
that if you put it at the feedpoint, the incredibly tedious pruning
process is eliminated. You just have to get a couple wires "about
right", and the tuner does the rest (who cares if the resonance is at
13.5 MHz.. that's not a huge change). And, in the "thrown on the roof"
sort of scenario, as the roof grunge and moisture changes or the trees
grow up or get leaves on them, changing the native Z of the antenna, the
tuner automatically compensates.

It's a coax feedline, so it's easy to route. The matching is at the
antenna, so the loss in the feedline is less of an issue.

In this sort of thing it *is* useful to have some way to see if the
antenna has fallen apart or shorted out or is covered with wet leaves.
The tuner will happily tune almost anything, but you have no real way to
know if it's actually radiating.

Actually, a field strength meter in the radio room works wonders. If
it quits deflecting and you are pumping full power... oops.



I've used a couple techniques.. a
monitor receiver with a whip antenna is one; looking at NCDXF beacons or
WWV is another.

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."