Feeding a tower

[VA3VJC]

Hi  Gang , Richard here:

I am putting up 3 sections of regular TV tower soon. I plan on topping it with 32-33 feet of piping. that should be 1/4 for 80M and 1/2 for 40M. It will be on a cement pad and supported by the house 18 feet from the ground . So I guees thats a grounded  Structure. I heard of Shunt feeding these , like a Gamma feed . Can anyone give Me advice on this , like  "Ballpark" figures where to start from. Rod lenght , spacing , Shorting strap  and Cap value if needed. I would like to go 80/40M if it can be done ..

73 .....VA3VJC / Richard

[Pete, WA2CWA]

Hi  Gang , Richard here:

I am putting up 3 sections of regular TV tower soon. I plan on topping it with 32-33 feet of piping. that should be 1/4 for 80M and 1/2 for 40M. It will be on a cement pad and supported by the house 18 feet from the ground . So I guees thats a grounded  Structure. I heard of Shunt feeding these , like a Gamma feed . Can anyone give Me advice on this , like  "Ballpark" figures where to start from. Rod lenght , spacing , Shorting strap  and Cap value if needed. I would like to go 80/40M if it can be done ..

73 .....VA3VJC / Richard

"I plan on topping it with 32-33 feet of piping." Better plan on guying all this. Don't forget you need a bunch of radials. Google turned up 700 hits on "shunt fed tower". I see lots of great info there, even on the first page.
Also, for additional good articles:
Ham Radio Mag. Nov. 1979
QST Oct. 1982
QST Jan. 1984
'QST June 1984

You can also go here:
http://www.arrl.org/tis/
and search the QST Index (if member) and also the CQ and Ham Radio Mag. Indexes for "shunt fed tower" articles.

I did a shunt feed of my tower for 160 meters years ago. Always seem to be a noise magnet.
 Finally went to an inverted vee. Actually your tower plus additional mast would make a nice center support for inverted vee type antennas.

[Fred k2dx]

While you could do feed it, being that close to the house would really not be a good thing, IMHO. Your radials would be a problem, the support arm would need to be insulated, you most likely would pick up noise as well as get into electronic devices in the house, etc.

If it could be erected away from the house it would be better. Use insulated guys.

[VA3VJC]

Hi again , Richard:

Thanx for the replies. I never thought about the heigth factor , never entered my mind. My realestate is very limited , 20 X 30 foot rear yard , if that , plus Teley and CaTV trunk lines and Amps along the back fence line. Thats why I decided to go Vertical next to the back Porch, and guying would be a problem.

At the moment all I have up is a 40M "Beer Bottle ground mount"  1/4 Wave with 4 ground rods pushed in the dirt at 45* angle , Coax fead strapped to the back Deck. It does work on 80/20 M .. but not that good. I guess I'll have to thinkup some other plan for 80 meter , or get a Tuner to make the HW-100 Xciever happy.  Thanx again for the input..

73.....VA3VJC / Richard