Topband: Fw: GAP VERTICAL QUESTION

[Charlie Cunningham]

Wow, Dave!

That sounds great!!  Could you support a vertical 1/2 wave for 160 with a
balloon? You could end -feed it at the base through a 1/4 wave of 450 ohm
ladder line and it would be a FEARSOME 160 antenna!  And the whole radial
issue goes away!!  I've operated a vertical 1/2 wave for 40m this way with
GREAT success! Even added a reflector and director to make a full-size
vertical 3-element yagi for 3Y0 and SE Asia on the evening 150 degree LP -
Great DX antenna! Worked Bouvet first call in a HUGE east coast evening
pile-up!  :-)

Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of DAVID
CUTHBERT
Sent: Saturday, December 15, 2012 10:59 AM
To: Michael Tope
Cc: topband at contesting.com
Subject: Re: Topband: Fw: GAP VERTICAL QUESTION

Mike that QTH looks alot like the Great Salt Lake of Utah where I have
operated a few 160 meter 'tests running a balloon vertical.

     Dave WX7G

On Fri, Dec 14, 2012 at 9:52 AM, Michael Tope <W4EF at dellroy.com> wrote:

>
>
> On 12/13/2012 3:14 PM, Tom W8JI wrote:
>
>> Somehow they thought moving the feedpoint eliminated the need for 
>> radials with an electrically short antenna, when the real mechanism 
>> was a 1/2 wave vertical was converted to a 1/4 wave groundplane 1/4 
>> wave above ground and it only got a tiny bit weaker. The groundplane 
>> still had 8 radials, but they were hundreds of feet in the air.
>>
>> There was some more stuff about offsetting the feedpoint in that 
>> handout, but nothing that remotely applied to a fractional wavelength 
>> vertical just sitting on the dirt with a few radials laying directly on
the lawn.
>>
>> They got rid of lossy traps and loading coils by using even lossier 
>> coax and some folded wires for a loading system.
>>
>> This is all why, as frequency increases and the current and voltage 
>> moves up the antenna, the GAP on most bands isn't terribly bad.  This 
>> also why it is a real dog of an antenna on 160 and 80, where it is 
>> very short electrically, has no ground system, has an exceptionally 
>> poor loading method, and where it folds the radiator back and forth 
>> which suppresses radiation resistance.
>>
>> This is why a ten foot mobile antenna can tie it or beat it on 160, 
>> and why it is reasonably on par with anything else on most bands 
>> above 80 meters.
>>
>> 73 Tom
>>
>
> I got hold of a brand new voyager about 7 years ago. The first thing I 
> did was throw away all that yellow coax stuffed inside the bottom 
> half. The fiberglass "GAP" for the elevated feed point makes a nice 
> insulator for a center loading coil. Then I added some top hat wires 
> with dimensions per WX7G's recommendation and fed the antenna from the 
> bottom as a standard ground mounted vertical with a bunch of radials.  
> For 80 meters, I put a short "yard arm" at the top with a pulley and 
> hung a wire in parallel with the aluminum radiator. For only being 
> 45ft tall this antenna has worked surprisingly well. I've since 
> lengthened it to 56ft and added an additional parallel wire for 40 
> meters. I use an Ameritron RCS-4 remote switch at the base to select 
> between 160 or 80/40 (the 80 and 40 meter vertical wires are tied 
> together). I use a 50 to 12.5 ohms Unun on the 160 side to raise the 
> feedpoint Z up to 50 ohms. With all these modifications done in haste 
> before various contests it aint pretty to look at, but it does seem to 
> hold its own against folks with shunt-fed towers and inverted-Ls (at least
the ones who don't use overly active antenna tuners :-)  ).
>
> Here are some pictures of it when I took a trip to one of the dry lake 
> beds north of here:
>
> http://www.dellroy.com/W4EF's-**Ham-Radio-Page/CQ160/2006.htm<http://w
> ww.dellroy.com/W4EF's-Ham-Radio-Page/CQ160/2006.htm>
>
> 73, Mike W4EF...............
>
>
>
>
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