OT - AV620 vs. R6000 antenna?

[Darwin, Keith]

I'm thinking about getting one of these 20-10 verticals to put on my
roof.  I want something that covers 20-10 including WARC bands.  I had
an MA5V which worked OK but the bandwidth was terrible and tuning was
way too touchy!  Yuck.
 
Having done a lot of research regarding verticals I'm rather untrusting
of the "no radials" lie that Cushcraft and others keep pushing.  Sorry,
but no radials means you have a lossy return path.  Still, these
antennas, with their short stubby radials, have the advantage of being
mountable on a pole some distance in the air which helps ...
 
So, anyone here have or use one of these?  Do they work great?  Are they
a waste of money?
 
- Keith KD1E -
- K2 5411 -
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[Vic K2VCO]

Darwin, Keith wrote:

> Having done a lot of research regarding verticals I'm rather untrusting
> of the "no radials" lie that Cushcraft and others keep pushing.  Sorry,
> but no radials means you have a lossy return path.  

Not true, really.  The "no radials" verticals such as Cushcraft's
actually are vertical dipoles, perhaps with some loading to shorten the
radials.  I built a 40 meter vertical with a 33' vertical portion and
four 8' inductively loaded radials (the inductance is common to all of
the radials).  According to EZNEC, the gain is about half a dB lower
than the same antenna with four 33' radials.  And as Moxon points out,
the chance of obtaining good current balance in the radials is much
better with this system (an imbalance results in unwanted high-angle
radiation).  The antenna works quite well.

Of course, using a plain ol' 1/4 wavelength vertical with a poor radial
system is asking for trouble.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Bob Nielsen]

On Jun 1, 2006, at 12:12 PM, Darwin, Keith wrote:

> I'm thinking about getting one of these 20-10 verticals to put on my
> roof.  I want something that covers 20-10 including WARC bands.  I had
> an MA5V which worked OK but the bandwidth was terrible and tuning was
> way too touchy!  Yuck.
>
> Having done a lot of research regarding verticals I'm rather  
> untrusting
> of the "no radials" lie that Cushcraft and others keep pushing.  
> Sorry,
> but no radials means you have a lossy return path.  Still, these
> antennas, with their short stubby radials, have the advantage of being
> mountable on a pole some distance in the air which helps ...
>
> So, anyone here have or use one of these?  Do they work great?  Are  
> they
> a waste of money?
>

K7LXC and N0AX published a report a few years ago where they compared  
several vertical antennas.  They didn't use radials, but had a ground  
screen with the antenna (IIRC) 7 feet above ground.  The report is  
available (for purchase) from <http://www.championradio.com>.  When I  
was looking for a suitable vertical after moving to this QTH, I  
bought a copy and it has a LOT of comparative data (they also wrote a  
similar report on Yagis).  The procedures they used represent good  
engineering practice (I once ran antenna test ranges in the aerospace  
business).  The AV620 and R6000 were not reviewed, but the R-8 was  
and appeared to be the best overall choice from 40-16 meters (the  
R6000 is quite similar for 20-6 meters).

Looking at the descriptions of the Hy-Gain verticals, the AV-620 is  
very much like the R-6000 except for using loading coils/capacity  
hats instead of traps.  The AV-640 and R-8 are similar in the same  
manner.  The Hy-Gain verticals are significantly less expensive than  
the Cushcraft equivalents, however.

I purchased and installed an AV-640 in late 2001 and have been quite  
pleased with the performance on all bands using both QRP and QRO rigs  
for casual operating, DX and contesting (I have worked nearly 200  
countries overall and about 100 QRP with this antenna, plus all but a  
few states).  My vertical is mounted on a pipe attached to the side  
of my house, about 15 feet above ground and approx. 250 feet from sea  
water, which undoubtedly helps.  The tuner in my K2 easily matches it  
across the entire band for each of the 40-10 meter ham bands.  I have  
even loaded it up on 80 and 160 (100 W or less--I wouldn't try much  
more) and made contacts of over 1000 miles during contests.

73 - Bob, N7XY


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[Jim Brown-10]

On Thu, 1 Jun 2006 15:12:41 -0400, Darwin, Keith wrote:

>So, anyone here have or use one of these?

As it happens, my good friend Randy, K9OR, has had an AV-620 on his
house in the middle of residential Evanston, IL (a Chicago suburb)
for several years. He has no radials. I am considering one for my
new QTH here in CA, and asked Randy what he thought of it. He
replied that he likes it a lot, and that it works quite well on the
HF bands, is decent on 40, and is surprisingly good on 30. Randy is
an old timer, a very good op, and has a decent technical education.
I trust his opinion.

Jim Brown K9YC


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