[TowerTalk] Foam cables and velocty factor
w8ji at contesting.com
Tue Nov 15 03:33:24 EST 2005
When ever I make a cable up, I high voltage test it for
When ever I buy a cable, I test it for high voltage
Best thing I ever learned to do, besides washing my hands.
> I have two questions:
> a) Where in the spectrum is this 248 foot hunk of wire
> i) 1680 KHz (no reactance),
> ii) 1800 KHz (minimum reactance & phase)
> iii) 1850 KHz (minimum resistance),
> iv) can't be determined from the data, or
> v) depends on what the word "resonant" is.
The only thing we can say without backing through it with a
Smith chart is NOT on your target frequency. Minimum *SWR*
is probably where the antenna is actually resonant.
(I fought MFJ deperately to get them to avoid calling X=0 an
antenna "resonance" indication in the 259 analyzer series.)
> b) What will provide the best "performance" for this wire
at 1830 KHz?
> i) Build a 2:1 matching device for the feedpoint,
> ii) Trim the legs shorter to move the minimum vswr to
> iii) Adjust the coax length to move the minimum vswr, or
> iv) depends on what the word "performance" is.
Adjust the antenna until SWR is minimum at 1830. It makes
you feel good, that's why I do it
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