[TowerTalk] Bobtail-Curtain

[David L. Thompson]

At 09:47 AM 12/11/97 -0800, Carsten, DL6LAU wrote:
>Hi,
>
>I am thinking about building a Bobtail-Curtain antenna for 80m (maybe
>another for 160m too). Reading in two different sources, one states to
>try a high L/C ratio for the L/C tuning network, the other source states
>low L/C ratio... 
>1. Any advice for good values to start with? (e.g. 80pF for 80m?)
>2. If I would use a variable air dielectric C, what would be the
>minimum    plate distance for 1500W (3000W) out ?
>
>Thanks for your help,
>
>Carsten, DL6LAU

Don't bother with the critical values for an LC network.  Attach the
feedline to the top of the vertical element and it comes close to 50 ohms
and you can QSY further without building up a large RF current.  Things to
consider:

1.      Use a line isolator to cut shield feedline radiation.
2.      Try to make the feedline come away at right angles to the feedpoint
for some distance (perhaps 25').
3.      You will find the so called half square (actually the basic W6BCX
bob-tail array) works nearly as well and is a lot easier to maintain
and phase.
4.      Remember the bob-tail is a broadside array so place it for best
results!

A full size basic bob-tail on 160 would be a great antenna!

73, Dave K4JRB 


--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search