Order Tray | Contact Us | Home | SIG Lists

[aprssig] aprssig Digest, Vol 53, Issue 25

Stephen H. Smith wa8lmf2 at aol.com
Sat Nov 29 02:15:32 UTC 2008


Charlie Gallo wrote:
>   
> Good question - I have a similar problem - there is a nasty RF hole to the north of me - with my digi down (which it has been for 1-2 years now)., but in the other say 270 degs I'm just QRM - the question is - put it back up, and fill the hole, or, cut down the QRM?  NYC has way too much QRM as it is, it's just that there are holes everywhere, due to hills and man made canyons.
>   

Build or buy a small 3-element yagi or dipole in corner reflector, and 
point it in the desired direction. The 3-element yagis and corner refs 
are often available in end-mount designs that can clamped to an existing 
mast beneath the top and pointed in the desired direction.     The small 
3-element version of a yagi will have a fat forward lobe approximately 
70-90 degrees beam width that can neatly fill in your hole while sparing 
the rest of the world.

Another DIY  REALLY cheap approach is to build a quagi - one full 
wave-length loop and two half-wave straight pieces of rod or wire stock 
through the diameter of a piece of PVC pipe.   (The standard quagi 
designs published show one with 8 elements; just build the first three 
elements of this design.)   The biggest problem in home-brewing VHF and 
UHF antennas is the feed system where the coax attaches.  In a quagi, 
the driven element is a simple full-wavelength of wire or tubing bent 
into a square and directly fed by the coax -- couldn't be simpler.      
You can throw one of these together out of #12 or  #14 house wire and 
PVC pipe in about an hour.   






More information about the aprssig mailing list