[RFI] High local noise level...

Jim Brown jim at audiosystemsgroup.com
Sun Mar 15 03:17:36 EDT 2015

On Sat,3/14/2015 5:50 PM, Kenneth G. Gordon wrote:
> If this is so (and I am NOT arguing with you about the need for better
> bonding) why is it that my noise disappears when I disconnect the
> antenna?

Did you study the tutorial?  A fundamental cause of triplen harmonics of 
the power line (divisible by 3) is leakage current from the power line 
causing a voltage drop on the "green wire where that equipment is 
powered, making the chassis "hot" with that power line buzz.  Every such 
chassis "grounded" at a different point is at a different potential. If, 
for example, your antenna is grounded somewhere else, that determines 
the AC potential of your radio. The DIFFERENCE in potential between the 
radio chassis and every other chassis is ADDED to any unbalanced 
interconnection. Like, for example, between the radio and your computer.

On Sat,3/14/2015 8:08 PM, Mike Martin wrote:
> If you haven't made changes in your shack its unlikely the cause is 
> bonding on your equipment. However it is likely to have a rectified 
> power line noise accuring on only the positive half cycle. Can you 
> send me a wave file if your noise, I'd like to hear and analyze it.

One possible (likely?) change is the addition of the unbalanced 
connection to the computer for analysis of the signal. :)

73, Jim K9YC

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