|[AMRadio] Re: new antenna...|
brett.gazdzinski at verizonbusiness.com
Tue Feb 6 08:52:21 EST 2007
Ok, the new antenna seems to work well overall,
I seem to get good reports from the far end stations,
and the receive signal level is very high.
I can run full power without anything arcing or melting,
the roller coil in the heathkit tuner gets slightly warm
after a while on full power (600 watts carrier), which
is likely normal, its not hot...
But I have a question.
When fine tuning it, I found the antenna tuner would
arc at full power until I cut the antenna down 3 feet
on each end, and cut about 5 feet off the open wire line.
I forget what the length was that I started with, 50 or 55
feet each side before cutting to get the antenna tight, I
will have to measure it next time it warms up outside.
I assume the cutting just changed the voltage/current points
so the tuner sees a lower voltage point.
So far so good, now for the questions:
I read that an antenna can be about 67 feet (33 feet each side)
and fed with about 40 feet of open wire line and it will
work on 80 and 40.
Although it wont work on 80 as well as if it was longer,
it will be resonant.
The question is: Does a resonant antenna work better on
Since the antenna is 100 foot long roughly, will it tend to
pick up more noise if used on a lower then resonant frequency?
Does the vertical feedline acting as part of the antenna
pick up vertical type noise?
A 100 foot antenna would resonate someplace around
5 Mc? and would it pick up more noise because its resonant there?
The antenna is 100 feet long now, and the ends are right up
against the trees, but I could add loading coils to make
the antenna resonant at say 3880.
Would that improve receive any?
Would it remove the vertical noise (if any) from the open
I don't know what that would do the SWR on the feedline,
it might move the current and voltage points around, but it
might be better overall then 100 feet.
What do you guys think would happen if I added loading coils?
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