View Single Post
  #18   Report Post  
Old January 8th 09, 04:53 PM posted to rec.radio.amateur.antenna
[email protected] nm5k@wt.net is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 757
Default Installing a Ladder Line to the house

On Jan 8, 7:50*am, "Ed Cregger" wrote:


The aversion to transmatches is a ham cultural trait that has no basis in
reality, just as the CB'ers are hooked on resonant 50 ohm antennas. It's a
characteristic of the culture(s) of both types of operators, with no basis
in practical operating engineering.

Ed, N2ECW


I wouldn't say that. As an example, I've done tests showing that no
matter how careful I am with the tuner, it's settings, decent open
wire feeder, etc, I could never quite equal the performance of a coax
fed
dipole when feeding the same antenna using the tuner and ladder line.
Quite close granted, and to many people a non issue, but there *was*
a difference. Of course, the coax fed dipoles I use would generally
be considered a single band antenna. But that's no problem here.
But if I have my way, I avoid tuners if possible. I'm trading the
ability of fairly efficient multi band use, for the slightly more
efficient
coax fed single band antenna. I want to radiate every drop of RF I
can.
Also the settings of the tuner are fairly critical for the most
efficient
use. I have a 989c also, and I have done extensive testing with it
using various settings vs efficiency.
I found with the usual T network tuner such as the 989c, you might
be able to tune a load with 25 or more settings. But only the setting
using the least inductance will be fairly low loss. All of the
settings
that use more inductance than required show more tuner loss.
Up to about 20% of your power is lost in a worst case scenario.
So that is another issue. Small, being as one can make sure to
use the least inductance, but it's just another thing to fuss with
when changing bands.
Myself, I prefer to use multiple element antenna elements to
provide multi band capability. The system efficiency is very high,
and I don't have to do anything when I change bands.
It's not using a resonant antenna that makes it very efficient.
It's the ability to use the 50 ohm radio to a low loss 50 ohm
feed line, straight to the appx 50 ohm antenna without any
semi lossy mickey mouse stuff in between. :/
Now if I were required to use only one wire for all bands, I
wouldn't have any problems using ladder line and the tuner
to feed a single dipole. It will work quite well, and being I don't
have the coax fed to compare to, no one will notice the
difference.
But I bet they would notice a slight difference if I did have
both to compare to. The reason I know this is because I
have tried it. "75m" I could see the difference on receive, no
real need to compare on air reports.
But I did anyway, and as expected, they saw about the
same difference between the two systems.
When comparing the ladder line and tuner system vs the
coax system, if I had a signal that was 40 db over S9
on the tuner system, it would bump up to about 45 db over
S9 with the coax feed.
For me to see that large a difference on receive, the tuner
loss can not be considered to be just an illusion or not
based in reality.
I have no problems with anyone else using one, but I think
it's a stretch to say that anyone that prefers to avoid one
is trying to emulate a CB'er.. :/