[RFI] RFI on 40 meters tracked down to Solid State Mini Fridge

[Jim Brown]

http://k9yc.com/RFI-Ham.pdf
Bad fingers!

73, Jim K9YC


On 1/13/2025 11:16 AM, Jim Brown wrote:
> On 1/13/2025 9:16 AM, Don Kirk wrote:
> 
>> Next step will be to try various filters that I have on the power cord to
>> see if we can eliminate the RFI.  Note: The fridge plugs directly into a
>> 120 Vac outlet (no external power supply) and it uses a 2 prong plug.  It
>> also has a power jack if you want to power it with a 12 Vdc 3 amp power
>> supply.
> Hi Don. Thanks for the NAQP QSO.
> 
> The unit is feeding common mode RF current to the power system in that 
> home, which is acting as an end-fed long wire. The first thing I would 
> try is to wind the power cord through a #31 Fair-Rite 2.4-in toroid 
> following the recommendations  in my 2018 Cookbook for the transmitting 
> chokes. Alternatively, wind as many turns as you can through a 1-in i.d 
> #31 clamp-on, WITH THE TURNS BEING IN ORDER AROUND IT! See Fig 28b and 
> 28c in RFI-Ham.pdf at kyyc.com  If the power cord isn't long enough, or is 
> too big, add a choke into a short section of power cable. Wind that 
> choke with as many turns as you can in a single layer of #18 zip cord. 
> This choke is for maximum effectiveness on the lower bands.
> 
> Traditional power line filters are unlikely to do much, because they 
> need access to the chassis of the source for their differential mode 
> networks to work.
> 
> 73, Jim K9YC
> 
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