[Elecraft] OT - R8 antenna evaluation

[w7aqk at cox.net]

Hi All,

I would like to compliment Jim Brown's analysis regarding verticals and
height above ground.  Based strictly on personal experience I would agree
with just about everything he said, and now I know why!!!  Hi.

For years I used a Cushcraft R7 vertical, and I soon found that when it was
mounted off the ground somewhat it performed much better.  Of course, these
antennas are compromise antennas, but still you can improve your results
with some experimentation.  Nothing produced better results for me than
elevating the antenna.

A number of years ago I purchased a copy of the study Jim refers to which
was authored by Ward Silver and Steve Morris.  This was published in about
2000, and many of the antennas they analyzed have been replaced or modified
somewhat by newer offerings.  However, the crux of the info is still very
relevant.  I think Jim is suggesting that any of these antennas will work
better if elevated.

Subsequently I acquired a used R8, which is similar to the R7, but an
improvement in some ways.  It is taller, but still uses much the same
matching unit at the base.  It also purportedly covers 6 meters, which the
R7 does not, but my results there have been marginal.  Still, the R8 does
seem to perform somewhat better than the R7.  In the analysyis by Silver and
Morris, I think they more or less conclude that the R8 was the best of the
bunch, at least if you only compare the bands each antenna is capable
of--some of the tested antennas covered 80 meters, which the R8 does not.

My R8, like my R7 previously, is mounted approximately 20 feet off the
ground--just above the top of my roofline.  The performance is much improved
over a simple ground mounted system.

Neither the R7 or the R8 produce very stellar results on 40 meters, but they
do work, and DXing is possible in decent conditions.  Since I favor CW, that
helps too.  SSB results are not so great, which tells me the antenna is
struggling a bit on 40 meters.  Not a big surprise!

Since then I acquired a used Sigma 40XK, which is a vertical dipole.  This
is another NB6T design, while he still owned Force12.  On 40 meters this
antenna works better than my R8, and I have it elevated, but only about 6
feet.  Based on Jim's analysis, I think it should be even a good bit higher.
I actually would have expected that, but Jim makes it obvious.

I also have another N6BT design, the Bravo 7.  This is, according to N6BT,
also a vertical dipole, but it looks more like an ordinary vertical, with
adjustable loading at the base.  I heard N6BT make a presentation about
these newer designs of his, and he reported very good results.  However, I
think his results are substantially based on being mounted over salt water!
Notice the dramatically improved results in Jim's analysis when mounting
over salt water.  My own results using this antenna are not all that good,
at least not on 40 meters.  It does seem to work fairly well on other bands.
On a couple of occasions I've had this antenna somewhat higher, and although
I don't have measurements to confirm it, the results did seem to be better.

So, although my results don't prove much, they do compare favorably to what
Jim says.  I've tried various antennas, and with the same apparent
results--higher is better!

Dave W7AQK