On 11/22/2022 2:36 PM, Al Lorona wrote:
1/ interfered with FM broadcast radio.
2/ caused the internet to drop out every time I keyed up on the lower bands.
Am I the only one? Those of you who run high power all the time... how do you
deal with these annoyances?
Both are caused by lousy design of the equipment. Band-aids are SERIOUS
common mode chokes on every wire connected to the victim. Follow
guidelines for HF transmitting chokes for the bands involved, winding
each individual cable through a #31 2.4-in i.d. toroid. Those wires are
receiving antennas coupling RF into that badly designed stuff, and
chokes kill RF current on them.
http://k9yc.com/2018Cookbook.pdf
3/4-in and 1-in i.d. #31 clamp-ons can work with 4-5 turns, but they
MUST be wound in sequence around the core. See the photo on page 10 in
http://k9yc.com/KillingReceiveNoise.pdf
As Vic has noted, use a serious choke at the feedpoint of every antenna,
use only coax-fed antennas, matched to the feedline resonant on the
bands where they are used, using that same Cookbook as a guide. Try to
locate antennas as far as practical from victim equipment. An end-fed
antenna, vertical or otherwise, ending in the shack is a recipe for RFI
to equipment. ALWAYS provide a serious counterpoise for any end-fed
antenna. If you don't, that antenna will use everything in your home as
a counterpoise, causing RFI.
In summary, take antennas seriously, -- their design, their location,
chokes at the feedpoint, bonding in the shack. Avoiding the problems you
describe is nothing more or less good engineering practice.
Also, some cable/DSL modems are notorious for RFI susceptibility. W8JI
solved a problem by complaining to the vendor, who gave him a
replacement. This usually requires taking the complaint up one or more
levels.
73, Jim K9YC
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