I think that that theory is nuts.  Moving the coil to a different
place along the length of the cable might change something. But if I were
you, I might just leave it alone, because it is working and you can tune it
over much of the band.  I don't see much value in cutting the coax shorter.
Having said all that, I suspect that the coax is probably part of the
radiating portion of the antenna, so ,if there's a problem with RF in the
shack, the coil should be closer to the antenna than to the rig.

Lloyd Rasmussen, Kensington, Maryland
Home:  http://lras.home.sprynet.com
Work:  http://www.loc.gov/nls
 
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Tom Behler
> Sent: Thursday, November 17, 2011 8:43 PM
> To: [log in to unmask]
> Subject: Re: SWR's continued
> 
>     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.