[Elecraft] RF noise on 80M with KPA500 plugged into AC outlet

[Jim Brown]

On Tue,10/4/2016 8:18 PM, John Freed wrote:
> Here is an interesting situation.  On 80 meters (3.980 MHZ) the background noise goes from S7 to S9+20 when I plug the KPA500 into the AC outlet.  I have not turned on the Amplifier, just plugged it into the AC outlet.  I disconnect the power cord from the amplifier at the amplifier and the noise remains.  I unplug the power cord and the background noise drops back to S7.  This only happens on 80 meters.  I have an idea the outlet may have a grounding problem.  I will test it tomorrow.
That's a good start.

> Any ideas??

Describe the antenna that you're listening to when this happens. How far 
from the shack?  If it's any sort of end fed antenna, what is your 
counterpoise?

Is this the "standard" line cord that came with the KPA500?  Is the KPA 
wired for 120V or 240V? Are you sure the plug is correctly wired?  For 
240V, the two "hot" wires must go between the two legs of 240V, the 
equipment ground (green wire) must go to the green wire at the outlet, 
and there must be NO connection to neutral.  For 120V, the transformer 
must be wired to phase (120V hot) and neutral, the the equipment ground 
must go to the green wire at the outlet, and there must be no connection 
between neutral and the green wire.

> I have a ground bar that all of the radios are attached to.  Single ground wire to an 8 ft ground rod just outside the shack. Hmmmmm!  (me scratching my head)

Is that ground rod bonded to all other grounds in your home/building?  
It MUST be. Is there a good ground (driven rod) at the service entrance?

73, Jim K9YC