Brian,
The answer is *bonding* as described by Jim Brown K9YC for minimizing
noise, hum and buzz.
Connecting everything to a common point may actually make the situation
worse (see the K9YC papers). "Grounding" everything will not minimize
noise, hum and buzz. Mother earth ground is not a 'sink' for RF, noise,
hum or buzz - it is only for safety from AC mains faults or suppression
of surges coming in on your antenna feedline.
Make your bonding follow the path(s) taken by the shields of your audio
cables and coax and you will have better results.
In other words, bond the computer to the soundcard device (if included),
and bond that to the KX3.
Bond the KX3 to the PX3, and bond the antenna tuner to the KX3
(following the path of the coax).
Then you may bond the antenna tuner to your common ground point for AC
mains safety and lightning protection.
The reasoning behind this bonding is to conduct much of the noise, hum
and buzz to the *outside* of the equipment enclosures rather than having
it conducted onto the ground plane of the PC boards.
In the long past, we did not have those problems. Connectors were
mounted on the enclosure chassis, and any noise, hum or buzz would be
conducted onto the outside of the enclosure where it was not likely to
cause any harm.
With modern construction techniques, the connectors are mounted to the
PC board inside the enclosure (and not to the outside of the
enclosure). That means that any noise, hum and buzz that is picked up
on the shields of AF cables or coax will be conducted directly onto the
ground plane of the electronics. The bonding between enclosures in
parallel to the audio and RF paths drastically reduces the coupling of
that noise, hum and buzz onto the circuit board and lets it flow
harmlessly onto the outside of the enclosures. This is the "pin 1
problem" that K9YC refers to.
If you do equipment to equipment bonding and bond the final element
(amplifier or antenna tuner) to your station ground, everything in the
station will also be grounded - assuming you use heavy wire or strap for
the equipment to equipment bonding - the shield stripped from old RG8
coax will do nicely as will #12 or larger wire.
Try it, it works.
For those who ask how to bond to a laptop computer, my answer is "any
way you can" - if you have a jackscrew for a VGA connector, that is an
obvious point - otherwise connecting to the shell of a USB or HDMI
connector may be your only choice - do the best you can.
73,
Don W3FPR
On 6/23/2016 7:31 PM, Brian Waterworth wrote:
I disconnected the USB acc1 cable from the small computer I was planning to
take with me to FD and the noise vanished. Each of the computer, the kx3,
px3, external power supply, external antenna tuner are all grounded to a
common point. The exception is the monitor and fan (it's going to be hot
:-).
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