On 11/8/2018 11:53 AM, Matt NQ6N wrote:
I've added substantial amounts of ferrite to the CATV coax, ethernet cable
and power cable.
Remember that ferrite chokes work by adding a high resistive Z in series
with the common mode circuit, and that resistance is maximized by
winding enough turns that the resulting choke is broadly resonant where
the problem is present. A #31 core clamped onto a cable without winding
turns is resonant around 150 MHz and will look like only a few Ohms.
Depending on the size of the clamp you're using, you'll need at least
4-5 turns to make it work on 40M.
Chokes should be applied to every cable connected to the modem,
including Ethernet to a wireless router or switch and the modem's power
cable.
More details in http://k9yc.com/KillingReceiveNoise.pdf ; When reading,
remember that antennas work in reverse -- that is, they receive like
they transmit. :)
73, Jim K9YC
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