On Thu, 10 Nov 2005 00:08:51 GMT, Cecil Moore wrote:


Owen, it's obvious that you deliberately picked 100 meters to try to
prove a point that you couldn't make otherwise. You chose an inferior
ladder-line that I wouldn't even allow on my property. Your attempts to
save face by dragging the discussion down some primrose path involving
minute details is interesting but not interesting enough to follow
you down said path.

I chose 100m as a round number that is practical and long enough to
demonstrate that at very high VSWR, the approximations that might hold
for shorter lengths and lower VSWR are no longer valid. Open wire
feeders well in excess of 100m are practical, but ladder line with
very high VSWR isn't.

(On the other hand, your 75' "standard" is about enough to reach the
feed point of a medium height antenna directly above the shack, and
might be argued as a minimum practical length for a good antenna.)

The ladder line I chose was one of the four that have reasonably good
characterisation (by N7WS) and it wouldn't matter much which of the
four you chose, they are fairly similar... I chose the first one on
the list. (The last one on the list, 554 with 25:1 load SWR give 5.6dB
against 6dB or 551... I wont bother checking the others.) No, I did
not deliberately choose an inferior ladder line.

Owen
--

Owen Duffy wrote:
I chose 100m as a round number that is practical ...

328.1 feet is NOT a round number. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Owen Duffy wrote:


(On the other hand, your 75' "standard" is about enough to reach the
feed point of a medium height antenna directly above the shack, and
might be argued as a minimum practical length for a good antenna.)

As opposed to the standard full height backyard antenna with 100 meter
feedline which would then be something more like this:

http://www.kkn.net/gallery/hcjb/hc15

;-)
ac6xg