[TenTec] Field day antennas (OT)

[Ralph Matheny K8RYU]

My preference for 300-ohm line over 450 is that at the tuner end of the
line with line lengths that seem typical I have a more moderate load for
the Matchbox to deal with.  I'd prefer to avoid either very low or very high-Z
loads if possible.  I'm not saying that 450 line isn't OK, I just think that
in most cases the 300 ohm is a better choice.  This is especially true with
the horizontal loop which is usually a couple hundred or so ohms on most of
the bands.  There's a chart in QST a while back which shows feed point 
loads for various bands.

Tuner wise, the best setup is to design the tuner for the job, cancelling the 
reactive element and then matching the resistance.  Folks who manufacture tuners
don't have the luxury of doing that as they want to sell tuners to as many as
possible.  I've often wondered if I'd be ahead to make a tuner for each antenna
leaving the other stuff in the attic.

As for the Johnson Matchbox, it has the further advantage of being quite selective
and reduces intermods, a real plus on Field Days.

For Off-center fed antennas, I think those can be made to work very well with the
correct design, a well-balanced tuner, etc.  I doubt there is any real advantage 
performance-wise over other feed systems. All can be made to work well, with care
of course.  One OCF antenna that I have used on 30-Meters for a long time which 
works very well is a full-wave wire fed at a quarter wave from the end.  That 
gives a nice 4-lobe (clover leaf) pattern which might be good for FD, depending
upon one's location.  It is a one band antenna, however......

One mans' opinion...

de K8RYU