[Elecraft] [PX3] Carrier Null

[Joe Subich, W4TV]

On 6/3/2016 10:03 AM, Don Wilhelm wrote:
 > The bonding wire eliminates much of that "pin 1 problem".

That is only true of two conditions are met:
1) the case is metal (conductive)
2) the case is tied to the power supply return (negative) at
    the power input.

Otherwise, *bonding* tends to circuit board "ground plane" to
circuit board "ground plane" and spread the noise through all
of the connected devices - particularly if the device does
not have a single "ground post" and the bonding is connected
haphazardly to whatever case/chassis/connector screw is handy.

73,

    ... Joe, W4TV


On 6/3/2016 10:03 AM, Don Wilhelm wrote:
> Joel and all,
>
> Use BONDING rather than "Grounding"
>
> You may create more noise problems by attempting to "ground" everything.
> "Ground" is not a sink for noise and RFI problems, it is only protection
> for AC mains safety and lightning surges.  Grounding will not carry away
> noise that is picked up on the shields of connecting cables, and in some
> cases may even make it worse.  Yes, you should have a good Mother Earth
> ground in the hamshack, but it will likely not help with noise, hum and
> buzz problems.
>
> Take the advice of Jim Brown K9YC and BOND the equipment enclosures
> together.
> In other words, connect the KX3 and PX3 enclosures together with a heavy
> wire or braid.
>
> What you accomplish by bonding is to take a major portion of the noise
> that would appear on the cable shield(s) and conduct it to the outside
> of the enclosure so that it does not get onto the ground plane of the PC
> board.
>
> We did not have that problem years ago when all connectors were mounted
> to a metal enclosure.  The outside of the cable shield braid was
> connected to the outside of the enclosure.
> But modern construction techniques connect the shields of cables to the
> ground plane of the PC board and not to the enclosure.  So any noise
> present on the outside of the cable shield is conducted into the
> electronics.  The bonding wire eliminates much of that "pin 1 problem".
>
> 73,
> Don W3FPR
>