[Elecraft] [K3] Serial interface noise issues

[Rick Bates]

Wall wart power supplies are notorious for creating RF noise (and audible
hum).  My stock HP laptop power supply generates a vast spectrum of noise
but the triple source (wall, 12v, aircraft) replacement is mute on all
frequencies, same brand.

So part of the test should be removing ALL power sources, not just a shut
down or power off.  With all the remote controls used these days, it is rare
that electronics are really off unless unplugged [also stops parasitic
consumption of energy if folks are sensitive about that].

Note that on some computers, chassis ground is NOT audio ground and I'd
suspect the same is true of some radios (true for at least one of my
Batwings).  Chassis to chassis bonding may increase noise in that case.

Rick WA6NHC

-----Original Message-----
From: Jim Brown

On 11/1/2011 3:33 PM, tomb18 wrote:
> Do you think that this issuee could still occur with the computer off but
the
> cable still attached?  I have some issues with noise but have attributed
> them so far to the power lines.  I mean if the cable is picking up
> interference from somewhere else, then perhaps this could be an issue?

Unlikely, but not impossible.  Do the chassis bonding that I recommended 
-- this is good engineering practice that never hurts, is well known to 
drastically reduce hum and buzz, and to minimize RFI issues.

73, Jim Brown K9YC