On Sun, Dec 12, 2004 at 05:52:00PM -0500, ABowenN4OO wrote:
> I am considering a backup plus portable antenna. After some research and a
> lot of rationalization, I have decided that an MFJ AV640 will take care of
> my modest requirements. I owned an R7 Cushcraft some years ago, which
> worked reasonably well at about 8 ft off ground, but exhibited SWR changes
> if you elevated it higher or lower. It also did not like high power, over
> about 500 W.
>
> Anyone have comment or counsel on the AV 640? It appears to be free of the
> traps that gave problems when high power was applied to the R7. In any
> event, I probably would not run more than 200 W into the 640; even less
> with portable operation.
>
> It is somewhat cheaper than the competing "no radial" equivalents.
I have had an AV640 (Hy-Gain, not MFJ although that is probably just a
technicality) for over 3 years and am quite satisfied with the
performance. It is mounted at ~13 feet and I have only used it for QRP
and 100 watt operation, although I don't see any weak points which would
cause problems at higher power levels. Before purchasing it, I reviewed
the K7LXC/N0AX report on verticals, which does not include this antenna,
but gives a good rating to the similar R8. The lack of traps and lower
price are both pluses for the AV640, in my opinion. The VSWR bandwidth
on most bands (measured with a MFJ-269) exceeded the specifications. It
easily tunes across the entire 40-10 meter bands with the ATUs of my K2
and TS-570D. I have also used it with an HT on 6 meters.
The only complaint I have was that the wrong hardware was sent for
attaching the base of the antenna to the mounting plate. I called
Hy-Gain and was promised the correct parts but they never arrived. I
ended up drilling new holes in the plate and using a couple of U-bolts
from the local hardware store.
73,
Bob Nielsen, N7XY
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