If you are end-feeding a wire, and it's near a half-wave on the band
you're operating (let's say 32 3/4 feet, and 14.300 MHz) an end-fed wire
is going to be close to infinite impedance, and you need some kind of
Un-Un (9:1 being common) to step up from 50 ohms or thereabouts.
If you're trying to operate on the same frequency, and the wire is more
like 48 feet, the impedance will be a whole lot lower and no transformer
is indicated.
This is the myth of the "random" wire, and why one "random" wire works
like gangbusters, and the next "random" wire is kinda lousy.
Antenna theory matters.
73 -- Lynn
On 8/13/2017 9:09 AM, Walter Underwood wrote:
In July, five SOTA operators put up seven different antennas on a summit and
compared their performance with WSPR. Six of the antennas were mostly within 3
dB of each other. The EARCHI antenna (end-fed with transformer) was between 6
and 15 dB worse than the others. So in one experiment, the 9:1 transformer did
not help.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
