Guys:
I unexpectedly had some extra time here tonight, and just got off 160 meters
with some midwest hams, who gave me a real interesting theory about my 160
meter sloper, the excess coax I'm using for a feed line, and why it might be
throwing my SWR's off.
Here's the theory:
They said that using a 100 foot piece of coax as a feed line is never a good
idea because there is something in that particular length that is known to
throw antenna resonance off. They said there was an article in QST
documenting this fact a number of years ago.
They said that what I want is either a half wave-length piece of feed line,
or an eighth-wave length piece of coax. They say I should avoid a
quarter-wave piece.
If you do the math (i.e. 468 over the frequency in megahertz), a half-wave
piece of coax would be approximately 260 feet long. This is obviously not
very practical.
However, if one were to use an eighth-wave piece, that would amount to
approximately 65 feet long.
Since I seem to have about 40 extra feet of coax out in my yard at the base
of the antenna, cutting that off would almost give me that eighth-wave
length.
I wonder if this is really what I should now shoot for.
Of course, I do not have experience soldering pl259's, so I'll have to get
help there, but I'm really thinking this might be worth a try.
You guys know far more about this stuff than I do, so if you think this
theory is nuts, please don't hesitate to let me know.
Thanks for the continuing help with this issue, and I look forward to
working at least some of you on 160 meters around 1.845 MHZ tomorrow night.
73 from Tom Behler: KB8TYJ
----- Original Message -----
From: "John Miller" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, November 17, 2011 7:31 AM
Subject: Re: SWR's continued
> All I can say is that did happen to me the one time I coiled up about 50
> feet of coax, it actually made it try to radiate the rest of the coax and
> the SWR went crazy. The coax was fine, I cut off the extra and used it
> elsewhere later on, even uncoiled and thrown all over the place it was
> fine
> but coiled up, it wasn't happening at all. I'm just reminded of that which
> is why I say that.
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