[Elecraft] Anyone using a DESpole?

[dyarnes]

Hi All,

Someone suggested that the Cushcraft R7 was deaf on 20 meters.  Not 
so--unless you had a defective antenna or installation.  I will not suggest 
it is a great antenna, but it certainly isn't deaf!  I used (and still do on 
some occasions) an R7 for years.  Much of that was at QRP levels.  I've 
since replaced it with an R8, but I don't notice a substantial difference, 
although there may well be some added benefit.

Like all multiband vertical systems, these antennas do represent something 
of a compromise.  However, you might want to take a look at the extensive 
commercial vertical antenna analysis that Ward Silver, N0AX, and Steve 
Morris, K7LXC, put together some years back.  A number of verticals were 
compared, both to each other and to a full sized reference vertical system 
with a substantial radial system.  Of course, in most cases the reference 
antenna was better, but not in all cases.  Furthermore, the R8 (which was 
one of the verticals compared) had what might be considered to be the best 
overall performance of the bunch.  Some of the other antennas covered 80 
meters, which the R8 does not, but otherwise the R8 had relatively strong 
comparative results.  The R7, which was the predecessor to the R8, performs 
similarly in my view and based on my personal observation.

If the definition of "deaf" is based on a comparison to a beam at a decent 
height, I would tend to agree.  Similarly, a dipole at 50 or 60 feet will 
probably outperform the R7 and R8 as well.  I had a dipole at about 40 feet, 
and it was often a dead heat, with the vertical possibly doing better for 
DX.  Until you get a dipole a good bit higher than 1/4 wave, the take-off 
angle is pretty high.  The R8, if deployed reasonably, will give you a 
take-off angle of perhaps 20 to 25 degrees or so.  However, you get no gain, 
and maybe a bit of loss vs. a dipole.

If you are deploying your R8 (or almost any other vertical system) at ground 
level, you may not be doing it in the best way.  Mine is at about 18 feet 
off the ground, and works much better than when I had it near ground level. 
!/4 wave systems at ground level need an extensive radial system and good 
soil conditions.  I hear a lot of ground mounted systems that work well, but 
I don't hear many that don't have a really good ground system.  If you can 
move that system to your rooftop, you can get a way with a lot fewer 
radials.  Support for this can be found in articles by Rudy Severns, N6LF.

The R8 was about 1.4 db down from the reference antenna on 20 meters in the 
Silver/Morris study.  A couple of the other antennas did slightly better, 
but much worse than the R8 on 15 and 10 meters.  In any event, -1.4 db isn't 
great, but it isn't all that bad either.  If that's all you have room for it 
isn't bad at all!  On 40 meters the R8 was about 1/2 S Unit down from the 
reference antenna, but so were all the others, if not worse.  Those antennas 
that purportedly covered 80 meters were all 1 to 3 S units down from the 
reference antenna!

I'm not "hawking" the R8 (or the R7), but as compromise multiband antennas 
go, it isn't a bad choice.  I have a vertical dipole (Sigma 40XK) that I 
like even better on 40 meters.  It seems to be slightly better than the R8 
based on some RBN comparisons I've done.  It's a multiband antenna as well, 
but changing bands is a nightmare, so I leave mine on 40 meters.  By the 
way, you could build your own Sigma 40XK  look alike for a fraction of what 
they want for it commercially!

Dave W7AQK