Hi.
That is correct, because anything that changes the dielectric constant
between the two conductors affects the impedance of the transmission line
and probably the velocity factor as well, and it affects the way that it
tunes. Proximity to other metal objects such as other antennas, chain link
fences, and even aluminum siding on houses can cause all kinds of problems
with this type of antenna. I have even found that because this is
essentially a reactive load, even the length of the coax can make a big
difference. I had trouble with mine on 15 meters until I added 10 feet of
coax! That is why there is a recommendation to get it as far up in the air
as possible. Many of these variables become insignificant if you can get
it way up there, but if you can't (like myself) then you just fudge with it
until you strike a happy medium that you can live with. A 9 to 1 SWR is
pretty high, but some manual tuners can still handle that.
Also, I've discovered that after a couple of years the wire that they use
in some of these G5RVs can stretch pretty significantly. Mine moved so
much that the resonant point was at 3.2 MHz on 80 meters! I am in the
process of redoing mine with copper weld wire which tends to stretch less.
73, de Lou K2LKK
At 07:47 PM 4/2/2006 -0700, you wrote:
>Hi
>
> This sounds a little strange but you might try cleaning the latter line.
>I have heard that can be an issue with this type of feed line.
>
> God bless,
> Mark WZ0K
>God loves you!
>My personal prayer book.
>Add your prayer or pray for others at the following link.
>http://prayerbook.homewithgod.com/cgi-bin/prayerbook/multi.pl?131961113534708:24:0
>
>http://lists.topica.com/lists/funhamradio.
>http://groups.google.com/group/funhamradio-list
>
>http://funhamradio.bloki.com
>----- Original Message -----
>From: "Louis Kim Kline" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Sunday, April 02, 2006 2:06 PM
>Subject: Re: antenna problem
>
>
> > Hi Tom.
> >
> > Yes, I think that brushing up the R7 to get the corrosion out of the
> > joints
> > could make quite a difference. It's probably a first step in trying to
> > get
> > that antenna going. As for the antenna tuner in the TS850S, if it is
> > anything like the auto tuner in the TS450S and TS690S, it is probably a
> > pretty tolerant antenna tuner. I personally think that the AT450 that is
> > used in the two radios that I just mentioned is a real gem, and it
> > sometimes even outperforms the MFJ993 tuner that I have. Keep in mind
> > that
> > when trying to debug the G5RV, the ladder line cares a lot more about what
> > is around it than coax fed antenna systems do, so try to look and see if
> > there are any metal objects near it that could be affecting it. G5RVs
> > work
> > best when they are up in the free and clear, but few of us have that
> > luxury.
> >
> > 73, de Lou K2LKK
> >
> >
> >
> > At 12:54 PM 4/2/2006 -0700, you wrote:
> >>Thanks for all six of the responses I have received so far. The Kenwood
> >>850 has an internal antenna tuner. It worked fine last year at Handihams
> >>radio camp in Malibu. That was with a G5RV. The R7 is just like it was
> >>when I acquired it from the estate of silent key Bob Larson, except for
> >>one joint half way up the mast and the 10 radials at the base. Would
> >>polishing up the surface do any good or does rf not care? I couldn't use
> >>it San Francisco because my lot was only 22 feet wide, but now I have 75
> >>by 300 feet. First I'll try the suggestion from two of youto put the twin
> >>lead straight and perpendicular to the long line, but at an angle to the
> >>ground. I's new and connects directly to the transmitter. I've used two
> >>different coax cables on the R7 with identical results. The ground is
> >>fine. I could get the G5RV higher if I could figure out what to use as a
> >>non-metallic mast. Any ideas? Would it be worth buying an external
> >>antenna tuner to use instead of the internal a t in the K850?
> >>Again, thanks for all the quick help. I don't stay on this list because
> >>there is too much traffic for me to add to what else is coming through,
> >>but it is great to get back on now and then. I'm always available at
> >>[log in to unmask]
> >>Tom Karnes K6FUN
> >>73
> >
> > Louis Kim Kline
> > A.R.S. K2LKK
> > Home e-mail: [log in to unmask]
> > Work e-mail: [log in to unmask]
> > Work Telephone: (585) 697-5753
> >
Louis Kim Kline
A.R.S. K2LKK
Home e-mail: [log in to unmask]
Work e-mail: [log in to unmask]
Work Telephone: (585) 697-5753
|
