[RFI] 80/160M RFI in neighbor's oven circuitry (PART 2)

Jim Brown jim at audiosystemsgroup.com
Sun Feb 8 12:24:26 EST 2009

On Sun, 8 Feb 2009 07:56:20 -0800 (PST), Bill and Cindy wrote:

>Thanks for the suggestions!
>Adding a good ground system to the neighbor's breaker panel sounds easy enough.

And a complete waste of time. The earth is NOT a sink into which noise and RF is 
>The microwave/convection oven in question is the usual combination unit about
>half the size of a refrigerator. I pulled mine out of the wall and as suspected the
>unit's power cable is entirely in flexible conduit, it is hardwired into the house
>electric system. How can I apply snap-on material 31 cores to this? I doubt
>code will allow the wires to be exposed, will the cores be effective if snapped
>around the flexible conduit?

You've described a microwave that is permanently installed. Many microwaves are not 
-- they simply plug into a wall outlet. You cannot apply ferrite cores to the power 
wiring you've described.  To add a choke, an electrician have to interrupt the 
wiring, and you'll have to wind a choke with wire rated the use. 

Your problem is on 80M. For a ferrite choke to be effective on 80M it must have 
multiple turns. Again, study the tutorial. 

However -- I would FIRST go with either a capacitor across the line or a commercial 
AC line filter. And yes, do use a capacitor rated for the high voltages that can 
appear across  the line. 

Corcom and Delta make good power line filters. Something like a 20ESK6 should do the 
job, but it may not be small enough to fit where it needs to be installed. Go to 
www.cor.com to see specs and dimensions, then google on a part number to find them 
for sale by industrial electronics distributors. 


Jim Brown K9YC

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