[Elecraft] OT A/C RFI

[Jim Brown]

This is gross over-simplification, but it is, sadly, the thinking of the 
EMC community and the regulations on EMC.

I've written extensively on this, so won't repeat it here. Here's the 
most recent.

http://k9yc.com/KillingReceiveNoise.pdf

And, of course, k9yc.com/RFI-Ham.pdf

VERY little RFI is conducted INTO equipment via the power line. Most RF 
trash is conducted out of equipment by "the Pin One Problem" as a common 
mode current on cable shields and the power system "green wire." it is 
then radiated by that wiring, and ends up on our antennas like any other 
radiated signal.  This is the mechanism for radiation from CATV systems, 
power systems, and nearly all electronics.

RF trash is also radiated by wiring internal to equipment as a result of 
poor circuit layout and poor shielding. Both conditions must be present 
-- it's entirely practical to build unshielded equipment with no 
radiated trash using good circuit layout and construction. This 
mechanism is often important with "big" equipment like HVAC systems and 
solar systems.

73, Jim K9YC

On 7/19/2017 8:17 AM, Bob McGraw K4TAX wrote:
> There's basically two types of RFI.
>
> Conducted --- Being noise/RFI traveling through the wiring thus via 
> direct connection.  Conducted RFI can be attenuated to satisfactory 
> levels by including a power line filter in the system {preferably at 
> the source}. The filter suppresses conducted noise leaving the unit, 
> reducing RFI to acceptable levels.  It also helps to lower the 
> susceptibility of the equipment to incoming power line noise that can 
> affect its performance
>
> Radiated --- Being noise/RFI  via the wiring into the air, i.e. 
> transmitted.   Separation of power and antenna physically is often an 
> improvement.  Radiated RFI is usually controlled by providing proper 
> shielding in the enclosure of the equipment.
>
> Regarding separate circuits, in most all cases each circuit terminates 
> into the service panel to which all are then common. The advantage 
> I've seen with separate circuits is in the distribution of neutral 
> current.   A large unbalance in load between L1 and L2 results in a 
> differential  neutral current.  In this case, the IR value will cause 
> the neutral to be above earth/ground.
>
> Often, figuring out which type and source is the challenge.
>
> 73
> Bob, K4TAX
>
> On 7/19/2017 9:52 AM, Clay Autery wrote:
>> Hmmmm....  Jim...  I have a variable speed down-hole pump on my water
>> well...  reckon that could cause RFI via the AC wiring?
>> The down-hole pump is 220VDC on dedicated circuit, and shack is on a
>> separate dedicated circuit from same service with separate sub-panel.
>>
>> ______________________
>> Clay Autery, KY5G
>> MONTAC Enterprises
>> (318) 518-1389
>>
>>
>
>
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