[Towertalk] hygain 205ca

K7LXC@aol.com K7LXC@aol.com
Wed, 20 Mar 2002 21:36:55 EST

In a message dated 3/20/02 5:37:37 PM Pacific Standard Time, 
n8de@thepoint.net writes:

> 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 
am I. 

    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 
capacitance effects. 

    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. 

Steve     K7LXC
Tower Tech -
Professional ham radio tower work