[Towertalk] hygain 205ca
Wed, 20 Mar 2002 21:36:55 EST
In a message dated 3/20/02 5:37:37 PM Pacific Standard Time,
> When you raised the antenna to 80', did you measure the resonant
> frequency AT THE ANTENNA? .. or at the end of a piece of coax?
> The ONLY way to 'get it right' is to do ALL measurements AT the antenna,
> NOT down at the shack!
Well, you can measure all you want at the antenna but the only place
where it MATTERS is at the end of the coax and what the transmitter 'sees'.
Some antennas are wacky at the feedpoint but FB in the shack (I'm sure the
feedline loss has a little to do with it). As long as the radio's happy - so
I don't know why your antenna didn't change resonance when you got it up
in the air. The 13.650 resonance on the sawhorses is about right. Sounds like
you've got some interaction somewhere - guy wires? Wire antennas?
You only need to get it 30 feet or so off the ground to minimize ground
I seem to recall in the dark, distant past that someone said that
computer modeling had changed the dimensions to make the antenna play better
so maybe you don't have the newest dimensions. I think they used to be on the
old Hy-Gain/TELEX website.
Tower Tech -
Professional ham radio tower work