At 10:38 AM 7/4/97 -0600, John Brosnahan wrote:
>
>> Thanks and gud DX, 73 de WT9Q--Bob
>
>
>Minimize the error at the highest frequency by cutting to that length, since
>a couple of feet error on the lowest frequency is a smaller part of a
>wavelength
>percentagewise.
>
>But please note --CATV line can vary from .78 to maybe .86 VF or more. So
>your biggest error will be from the not well known VF. For best results
>determine the VF for the actual cables you are using. The velocity factor
>varies as to the percent of bubbles of air and can vary from reel to reel
>from the same manufacturer. I have even seen it vary from one end to the
>other of a roll--but not nearly as much as from reel to reel. Use any of the
>popular methods to determine the cable length--grid dip meter, or antenna
>bridge.
Amen, John. I cut mine to what I thought was the right length, given the
VF I'd been told, and discovered I needed about 10 feet of RG-11 to get the
length right. I used my Autek RF-1 to get the length correct, trimming the
RG-11 as needed, until I had a good half-wave-multiple at 3510. Works great.
73, Pete Smith N4ZR
n4zr@contesting.com
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