[TenTec] Omni VII Query

[Ron Zond]

Jerry

Thanks for the additional info.
I know it's not perfect, My understanding is taht at 1\4 wave intervals, the
"appearance" changes
from series to parallel, and back to series. The impedance at any given
point may be somethng
other than 50 ohms. 73.

Ron
K3MIY


-----Original Message-----
From: tentec-bounces at contesting.com
[mailto:tentec-bounces at contesting.com]On Behalf Of Dr. Gerald N. Johnson
Sent: Friday, December 11, 2009 8:52 PM
To: tentec at contesting.com
Subject: Re: [TenTec] Omni VII Query


On Fri, 2009-12-11 at 16:05 -0500, Ron Zond wrote:
> Val
>  Did you try different lengths of coax on the rig.
> Sometimes that will help by moving the 50 point to the rig output circuit.
> (The rig actually "sees" 50 ohms.
>
> Ron
> K3MIY
>
That's not really true. But what it does is change the phase angle of
the load to sometimes make it easier to match or to feed. The right
length can always make a reactive load purely resistive, but it will not
be 50 ohms. It will be higher or lower, and another quarter wave will
always give the restive impedance lower or higher, just the opposite.
Another length can make the impedance at the input end 50 ohms +/-
reactance that may be easy to tune out. But if a line has SWR greater
than 1, there is no line length (under a wavelength) that will give 50
ohms purely resistive. A very long line with 10 dB or more insertion
loss will show a 50 ohm input (pretty close) no matter what the load,
but that's putting most of the output power into heating the line, not
getting to the antenna for being radiated.

73, Jerry, K0CQ

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