On 12/9/2018 5:15 PM, Bob McGraw K4TAX wrote:
I don't know a darn thing about them other
than...........they work.
Define "they work." :) They don't blow up? You get signal through them
to the antenna? They reduce common mode current? They reduce RX noise?
You make QSOs with them in line? They make you feel good?
The REASON for using a common mode choke is to reduce common mode
current. That can reduce noise a bit -- the part of it picked up on the
feedline, and it can eliminate the part of TX RF coming into the shack
on the feedline as common mode current. By my definition, if a choke
does that, or can do that if there's noise, it works. If it doesn't do
that, or can't d that, it's not working or it's not a good choke.
Chokes installed on antennas rarely make a large difference in noise --
a few dB is typical if your antenna is close to the noise source, it
also picks up the noise. But if the antenna is far from the noise source
and the feedline runs close to the source, the reduction can be more
than a few dB. AND, when that DX you're trying to work is weak, that few
dB can be the difference between copying him or not!
73, Jim K9YC
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
