Regarding ===> "Message: 1 Date: Mon, 22 Jul 2019 15:59:44 -0700 From: <57jndenn...@comcast.net> To: <topband@contesting.com> Subject: Topband: RFI on TB "
As a starting point to check-out *everything* between the feed-line connection directly at the *antenna feed-point* and a receiver, connect a 50-ohm termination at the *antenna-end* of the feed-line (assuming 50-ohm coax). Is the "RFI" gone and no detected signals, if so, good. If *not,* you have bigger problems! Terminate the receiver (after removing the antenna feed coax from the receiver) in 50-ohms - record the S-Meter 'reading' . Replace the 50-ohm load on the receiver with the feed-line and record what the S-Meter is displaying - is it close to what was recorded with the 50-ohm termination ? If not, you have some serious clean-up work to do. You will be dealing with Common Mode (CM) currents that have to be eliminated. The "clean up" process is more easily accomplished if you have a near-DC-to-30MHz spectrum analyzer available to ensure you are not dealing with 10-pounds of 'stuff' in a 9-pound capacity flexible container - push it down 'here' and something pops-up 'there'. Once the CM-issues have been resolved, your receiver S-Meter will be, almost certainly, close to S-zero in the absence of desired signals and propagated noise. This is what I have been able to achieve in a big city environment at CN97uj using balanced dipoles and feed-point chokes. _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector