Of course I was being facetious calling them low-Q but forgot the smiley.
That is incredible SWR bandwidth for a shorty 40.
John
On Wed, March 14, 2018 7:25 am, john@kk9a.com wrote:
The low-Q loading coils probably contribute to the 250KHz SWR bandwidth
that K7LXC posted.
John
From: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 13 Mar 2018 20:44:36 -0700
## The main problem with the 402-CD is the loading coils.
http://www.qsl.net/ve6wz/intro.htm scroll down til u see the info on the
XM-240.
http://www.qsl.net/ve6wz/CC_coil.html 12 gauge magnet wire, wound butt
tight,
on a .75 inch solid fiberglass rod is as useless as it gets for a
40m loading coil. Q is through the floor..and coil losses are sky high. No
wonder they end up with a 50 ohm input Z..with NO matching device used.
The XM-240 is a direct fed 2 el 40m shortened yagi. When was the last
time
you saw a 2 el yagi that did not have a way less than 50 ohm input Z ?
The coil losses are sky high on the inferior designed coils, such that the
real feedpoint Z plus coil losses = 50 ohms..... = fubar.
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