Well, Carl
Your experience with your 6-wire cage vertical - 1/4 wave on 80 - AND 1/2
wave on 40 was not very enlightening or satisfying and led to some serious
misunderstanding!!
When you removed the radials - OF COURSE it was a "DUD" on 40 -if you
just
left the coax feed in place!! You were trying to end-feed a 1/2 wave
resonant antenna on 40m from coax - you must have a heck of a tuner, but
the
VSWR and mismatch loss were so high that you weren't delivering much of
anything to the antenna!! Most of your power was being dissipated in
heating
the coax operating at very high VSWR!! You could have turned it into an
excellent 40m antenna if you had end fed it through a 40m 1/4 wave open
wire
ladder line or fed it from the top end of a 40 m parallel tuned circuit
(cold-end grounded, of course) tapped for a match to your 50 ohm coaxial
feed line. If it still worked on 80 without the radials, there must have
been a fortuitous length of coaxial shield to supply the missing "lower
1/2"
of the antenna! But you solved the problem without ANY understanding and
put up 4 40m elements at 120 feet! The problem was NOT a "GROUND
PROBLEM" -
but was rather one of "operator head-spacing"! There must have been a
hellacious VSWR on that COAX trying to feed that 1/2 wave vertical cage at
the end with no radials. Your understanding of antennas, resonance,
matching
and grounding seems to leave a LOT to be desired! Perhaps some reading and
study would help!
Regards,
Charlie, K4OTV
P.S. A 1/2 wave vertical does NOT need a "salt water marsh" under it to
work VERY well! In fact a vertical 1/2 wave in free space also works very
well!!
-----Original Message-----
From: Charlie Cunningham [mailto:charlie-cunningham@nc.rr.com]
Sent: Sunday, December 16, 2012 9:16 AM
To: 'Carl'; 'Richard (Rick) Karlquist'; 'Donald Chester'
Cc: 'topband@contesting.com'
Subject: RE: Topband: GAP Vertical Question
Good morning, Carl
Well, a 1/4 wave vertical absolutely requires a "ground plane"!! A
vertical
1/2 wave - not really!
It seems that, in your observations, you are mixing the two? Any 1/4 wave
vertical absolutely does need an "image plane" to work against!
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Carl
Sent: Saturday, December 15, 2012 7:46 PM
To: Richard (Rick) Karlquist; Donald Chester
Cc: topband@contesting.com
Subject: Re: Topband: GAP Vertical Question
My own experience with 1/2 wave verticals is that they certainly do
require
a good ground.
Maybe a rod in a saltwater marsh is sufficient but not in many other
cases.
Examples:
A Shakespere CB whip in my 66 Corvette which was advervtised for
fiberglass
cars. It couldnt be heard a mile away with 4W. I added "radials" from the
base on the rear deck to the frame on all 4 corners and then it worked
much
better. This was back in the late 70's for several years.
A 80/40M 6 wire cage vertical, a full quarter wave on 80 and hanging from
a
tall pine tree branch at a prior QTH. With 60 65-70' radials it was
competitive on 80 and on 40. With the radials removed it was a dud on 40.
With another phased 1/4 wave on 80 it delivered the gain and F/B expected
and 40 was improved with a pair of figure 8's but still not up to
expectations. A 4el 40M KLM at 120' fixed that.
Carl
KM1H
----- Original Message -----
From: "Richard (Rick) Karlquist" <richard@karlquist.com>
To: "Donald Chester" <k4kyv@hotmail.com>
Cc: <topband@contesting.com>
Sent: Saturday, December 15, 2012 3:58 PM
Subject: Re: Topband: GAP Vertical Question
On 12/15/2012 12:03 PM, Donald Chester wrote:
From: charlie-cunningham@nc.rr.com
Could you support a vertical 1/2 wave for 160 with aballoon?
You could end -feed it at the base through a 1/4 wave of 450 ohm
But feeding a half wave vertical with the base near the ground
> still results in substantial ground losses without a radial system.
Don k4kyv
And this statement is based on what? Publications, measurements,
modeling?
I have built a number of 1/2 wave verticals without radials and
compared them to 1/4 wave verticals with radials. They are
indistinguishable in performance and certainly do not exhibit
substantial ground losses AFAIK. The PAR electronics 1/2 wave end fed
antenna seems to have a good reputation, unlike some GAP verticals.
However, I don't recommend feeding it through 1/4 wave of 450 ohm open
wire line. I just use an LC matching network.
Rick N6RK
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