Sal M. Onella wrote:
I am my club's sole source of FD points for UHF/VHF. I have beams for
2m & 70 cm, but maybe rhombics are better. From San Diego, most of my
DX FD contacts are in the same place: Los Angeles. I don't really
need a steerable antenna.

Well, OK... but it takes a LOT of on-site work before a large rhombic
can show any advantage over one or two decent long yagis. You'd need to
put up four masts in precisely surveyed locations, with enough guy
strength to keep four long spans of wire taut, and then terminate and
match the thing.

BTDT, and succeeded, but it takes far more work than you imagine. When
your club is trying to set up several stations all at the same time, you
may find you don't have enough effort to do it. There's a severe risk of
winding up with no VHF/UHF antennas at all. BTDT too...

And after having spent all that effort on a fixed beam, are you really
prepared to risk a sporadic-E opening in a completely unanticipated
direction?

Impedance matching to a 700 ohm antenna seems to be a daunting task.
If I used a 4:1 balun

That is actually the easy bit. You use the 4:1 balun with an
old-fashioned device called a "universal stub": a half-wave section of
parallel line made from a pair of old yagi elements. One end of the stub
is connected to the antenna, and two clips make a moveable tapping point
for the balun. Towards the far end of the stub, two more clips make a
moveable shorting bar.

Detailed dimensions don't matter at all, because you're going to slide
the shorting bar and the balun along the stub until you find the
combination that gives minimum SWR. It takes all of five minutes.

That was the easy bit... but it's probably the ONLY easy bit of the
whole project.

could I connect two or three independently terminated rhombics (one
over the other) in parallel to the balanced side?

Two stacked rhombics are easy to feed - connect the feedpoints by a
length of open-wire, and then connect the universal stub at the
mid-point. The counter-intuitive thing is that a pair of antennas that
could be hundreds of feet long need to be stacked only a few feet above
each other. But attempting to stack two rhombics will multiply your
rigging problems by a factor MUCH larger than 2!

Having experienced a large rhombic for VHF, I'd stay with yagis.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek