[Elecraft] PX3 Spike won't go away

[Brian Waterworth]

Hi Don,

Many thanks for your reply.  I have read Jim's and your advice and counsel
about RFI many times on this reflector and I am very grateful for your
response tonight.

I will give your advice a try.  I have some extra shield cable and can make
the runs short between the equipment.

For some context on why I went to a common point.  I read, what I thought
was an excellent article, about ground loops from the Flexradio site a
couple of years ago.  Here is the link:
http://kc.flex-radio.com/knowledgebasearticle50426.aspx

I thought that daisy chaining would introduce ground loops and hence the
reason I went to a common point.  However, I don't think you are advising
this.

Let me say it back to you: Follow the audio path first and then follow the
coax path.  For me,

   - Computer to the kx3 (using the computer's sound card for now)
   - Then bond the kx3 to the px3
   - Then bond the kx3 to the KPA500 (I am borrowing this for FD)
   - then bond the KPA500 to my antenna tuner
   - Then bond the antenna tuner to the station ground point
   - Ground the power supply to the station ground.


Again, thanks Don for the advice.  I will let everyone know how I do after
FD if my results change.

regards,
Brian
VE3IBW

On Thu, Jun 23, 2016 at 9:02 PM, Don Wilhelm <donwilh at embarqmail.com> wrote:

> 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
>> :-).
>>
>>
>>
>