View Single Post
  #13   Report Post  
Old September 11th 04, 12:36 AM
Jeff
 
Posts: n/a
Default


"BDK" wrote in
message -------------------------------------------------------------------------------




If I had my choice as one single antenna to use, I would probably pick
the home built ground plane (I can build one that will last forever),
with the ringo a close second. The scantenna's next only due to it's
fragility. I may build a HD one myself one of these days..

As far as impedance goes, it's pretty meaingless for receivers, loss is
much more of a problem.

I need to find a climber to change the coax on my ringo, and put up
another discone as a backup to it, for 2M/440. I don't want to get
ripped off for 300 bucks like I did 10 years ago, 25 of it was for
coming over the border into my town. That 150 yards cost 4 times as much
as the ground plane I made the day before cost me!

-------------------------------------------------------------------------------

I suggest you go back and study some rf transmission basics.
Impedance is important on recieve if you want to get maximum signal
transfer. In an impedance matched circuit you will get maximum
flow of rf, than in a non resonant circuit. This applies to recieve as
well as transmit. Why do you think they use that little 1.95$ 300ohm
to 50ohm transformer on the scantenna? It isnt there for looks. And no
my VR 5k wasnt suffering from intermod or overload, had an AM
filter, an FM filter, and a paging freq. filter on it and it works quite
well. If you build your own ground plane, I bet you will make the
elements to come out to 1/4 wave on the freq. you want it to work
best on wont you? Why? because a 1/4 wave is a 52 ohm load at
the resonant frequency. Thats what a discone does, it happens to be
a 1/4 wave on a lot of different frequencies, thats why you can xmit
on it. Scantennas work, just not well enough for me to have one up
and with the 1st freezing rain and wind that comes along it ends up
bent up like a pretzel. The only band where it outperformed the discone
was in the 152-155 band where the LEO's use in different counties.


Jeff