Jim/ K9YC
I am with you 100% on your comments below
my 80/ 160 verticals all run "10 lbs of ferrite" at the feed points but
that is because I run elevated non resonant radials these days. 5lbs of
ferrites just got to warm to touch, but that is fodder for a whole
different thread.� My "jungle" makes running ground mounted radial
systems unpractical.
Among other things� with my wire T's and L's I also avoid coax runs that
are multiples of odd 1/4 waves at the frequency of interest which helps
( how much ?)� didn't measure it a the time, but the Winkeyer stopped
locking up ......:)
Dave
NR1DX
On 1/1/2021 4:19 AM, Jim Brown wrote:
On 12/31/2020 5:01 PM, Michael Walker wrote:
Hi Ken
Chokes at both ends of the feed line are always a good idea.
At the base of the antenna, yes, so that the feedline doesn't become a
radial. More are probably wasted money. See my latest Cookbook at
k9yc.com/publish.htm
I have a similar setup to you but with elevated radials and I have
Mix 31 chokes right at the base of the antenna with an UNUN since I
am using 75 ohm coax and then more chokes at the antenna switch.
You can�t use enough chokes.
The only good reasons I've discovered for using chokes on feedlines
anywhere but at the feedpoint are 1) to break up the feedline into
lengths that won't be parasitic becoming parasitic elements to other
verticals; and 2) to prevent noise pickup by a mechanism quantified as
the Transfer Impedance of the cable, whereby shield current is
converted to a differential voltage inside the cable.
W3LPL has observed that #2 should not be an issue with coax laying on
the ground. I am not so optimistic with the CATV RG6 we often use for
RX antennas, whose shields are VERY flimsy at MF, but I always value
Frank's observations.
As to chokes at the station -- if they solve problems, they're putting
a band-aid on badly done (or missing) grounding and bonding. See
N0AX's ARRL book on the topic, and/or the slide deck for my talks
about it.
http://k9yc.com/GroundingAndAudio.pdf
73, Jim K9YC
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