Topband: 160 wire yagi

[Mauri]

Yes, it's true.
For some years I used a fixed two elements wire yagi @200 ft (almost 
straight elements), remotely tuning the passive element as a director or 
a reflector.
Some precise open wire trasmission line and element lenght allowed a 
remote capacitor to give the needed amount reactance and reverse its 
sign. (-j +j)
The antenna pattern was good enough while bandwith was pretty small. So 
far, the passive element had to be tuned precisely from the shack to 
keep currents high in any portion of the band. Obviously, this feature 
made the "split" operation a bit tricky.
Since the yagi impedance changes if the passive elements tunes as a 
reflector or director (the spacing was 0.14Wl), and 1.8Mhz is a wide 
band (must think about in percent), a flat match was impossible all over 
the band and the antenna SWR was a compromise.
Most of the times, in the favourable headings, the antenna had the same 
reception of a 660 ft terminated beverage, sometimes it was better, 
someother worse.
While producing a big signal, receivers suffered because of the huge 
signals of medium distance continental stations and for the same reason 
it was not uncommon to sutruggle because of "splattering" and clicks. 
(as you lower the antenna from ground below half wave, this problem rises)
Height from ground was (and remains) a key factor and it's not so easy 
to keep the yagi elements far enough from terrain.
All considered, unless one has a peculiar situation to utilize, a 
vertical tower as a transmitting antenna and a separate receiving system 
(I'd suggest beverages) could be an easyer, but very effective approach 
for Dxing on 160m.
73,

Mauri I4JMY

Il 10/09/2010 9.49, Pete Parisetti ha scritto:
> Top contest station IR4T in Modena, Italy, has a two element wire beam
> suspended from a water tower at 210'. Performance, as I remember from 15
> years ago, was astounding - once we managed to break the US pileup on
> 4U1UN...
>
> The design was the work of Maurizio, I4JMY, who I believe reads this list.
> You may want to contact him directly for more information.
>
> 73/DX
>
> Pete
>
> On Thu, Sep 9, 2010 at 9:18 PM, Craig Clark<jcclark at myfairpoint.net>  wrote:
>
>