Carol – Regarding the use of ferrite chokes to kill common-mode noise coming in
on the transmission line, look on the internet for “A Ham's Guide to RFI,
Ferrites, Baluns, and Audio Interfacing,” by Jim Brown, K9YC. It’s a very good
tutorial on how to construct and use chokes for common-mode noise.
--Art Delibert, KB3FJO
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
From: JC<mailto:n4is@comcast.net>
Sent: Thursday, November 23, 2017 2:58 PM
To: 'Carol Richards'<mailto:n2mm@comcast.net>;
Topband@contesting.com<mailto:Topband@contesting.com>
Subject: Re: Topband: Beverage construction
Hi Carol
The big issue with any RX antenna is common mode noise, the feed line can
interact with all other wires in your station, including AC wires 115Vac,
rotor cables etc.
Try this, on 9:1 transformer, remove the beverage wire and connect a 450
resistor. Removing the wire for the resistor de signal coming from the RX
antenna should be zero. Turn the preamplifier on, any noise you hear is not
coming from the antenna and it is common mode noise that you need to clean.
Choke can help a lot if you have a good ground connection.
73's
JC
N4IS
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Carol
Richards
Sent: Thursday, November 23, 2017 12:36 PM
To: Topband@contesting.com
Subject: Topband: Beverage construction
Hello all,
I finally put up a beverage antenna...about 400 feet long. I am feeding
it through a 9:1 transformer with some 50 ohm cable ( RG 59). I am
finding that it is noisier than my transmit antenna, contrary to what it
should be. The wire stays about 6-8feet above ground. ground rods at
each end, etc.
Any thoughts on the problem and a cure?
Thanks,
Carol
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