[Antennas] Re: increased ant bandwidths...

[DavidE Benedict]

223bthp at cox.net writes:
>Bob and Roy,
>
>It sounds like you both agree that power output from the transmitter is
>the
>only objective of any antenna tuner. What happens after that we have to
>accept if we want wider use of each antenna.
>
>If antenna tuners were placed at the feedpoint of the antenna, there would
>be little reflected power on the transmission line before it. An antenna
>coupler is always as close to the feedpoint as possible for this reason.
>
>When we want more tuning options in non-weatherproof assemblies right at
>our
>fingertips (and inside the zone of our lightning protection system), we
>have
>to accept the consequences. An inside antenna tuner still protects the
>transmitter and the operator, as long as we remember the output of the
>tuner
>(like a coupler) is 'hot' in more ways than temperature.
>
>Regards,
>
>Jack


What's realistic, though, for input and output power?

Lets face it, the major SWR loss in a tuned antenna system is loss in the
coax, ...and, typically only a few percent in a quality tuner. 

So, a huge SWR on lo-loss ladder line, or in using a tuner next to an
antenna feed-point, is almost negligible compared to a huge SWR between
the tuner and antenna using 50 feet of RG-58.

So, one needs to get a short transmission line which is lo-loss, et
vipola...mucho power out.

But, how much is the difference? Is it worthwhile to do some of the things
this indicates would be a good idea? How can we know?

For instance,...
If I put out 100 watts on 40 meters into a 10M dipole, tune it with a
tuner to 1:1, how much do I actually radiate when using 50 feet of RG-8?
-- Then what happens if I switch the parameters to 100 W on 10m using a
40m dipole?
-- Then what happens if I increase the coax length 10, then 20, then 30
more feet? 
-- It seems like a couple pages of line-item data something like this
would give a lot of wisdom on the Tuner/ SWR subject.

Anyway, there is such a mystique about SWR, tuners, etc.  
(I am whining there).

So, how about using rules-of-thumb & nomographs (sp?)? 
Everyone uses them, probably even the nuclear guys. So, why don't we have
simple (leave out all the not-so-power-robbing factors), and have,
generally, a lot more savvy within the Amatuer community about antennas &
tuners, and IN & OUT power differences which simple things aid or cause to
be worse?

I don't have a dog in this competition because I operate only mobile and I
have a Larry's Screwdriver, 160m-6m, and do quite well, so my problems are
pretty much solved with this
"dummy-load-with-a-capacity-hat-and-a-tuned-inductor". Maybe I am
unrealistic but I'd like to see a lot less mystique about these antenna
things.

David B.
W7DBH
Mobile-Only ...in NW Oregon