[Elecraft] K2, distorted audio signal

[W3FPR]

Jim and all,

The K2 does not use a multi-layer board, it is only 2 sided.
The standoffs only provide a ground path tor the covers.
Testing without the covers is a practical way to test.

Multi-layer boards fir elecraft only came into being with the K3S RF board.
All else you said is valid.

73,
Don W3FPR

On 7/30/2025 3:54 PM, Jim Brown via Elecraft wrote:
> On 7/30/2025 8:08 AM, Michael Carter via Elecraft wrote:
>> The standoffs likely provide localized grounding in that section of 
>> the RF board.  I'll have to look at the corresponding top-side 
>> circuit area to know which circuits might be affected by lack of a 
>> local return path for currents.
>
> Hi Mike.
>
> You misunderstand the nature of "ground" and how signals are carried 
> on a circuit board. Most circuit boards are multi-layer, where traces 
> are above a continuous "ground" layer, and the traces form a 
> transmission line with return current on the region of that layer 
> directly them. This prevents crosstalk between circuits, and is the 
> equivalent of having all of those signals carried on coax! It also 
> prevents the radiation of those signals. In the most sensitive 
> equipment, the traces are sandwiched between two "ground" layers, 
> which provides even greater isolation.
>
> A connection to mother earth is not a sump into which problems are 
> poured. It's only functions are 1) Lighting protection -- absolutely 
> critical, and all earth connections and every chassis in our homes 
> must be bonded to it. 2) As a component of most receiving antennas. It 
> has nothing to do with how equipment works.
>
> A connection to mother earth does NOT make transmitting antennas work 
> better -- indeed, it makes them work worse! That's because, while 
> end-fed antennas like verticals and long wires need a path for return 
> current, the earth is a big high value resistor that burns transmitter 
> power. That's why it's important to have radials or another form of 
> counterpoise for these antennas.
>
> And it IS critical for all cable shields to be connected to the 
> Shielding Enclosure (the chassis) at the point of entry for the cable 
> shield to work. And a shield that is not connected to the chassis, but 
> goes through a hole in the chassis to the circuit board, carries 
> shield current into the box, and is a recipe for hum, buzz, and RFI 
> (noise, RF feedback). Failure to make this connection is called "The 
> Pin One Problem," because it was first realized by Neil Muncy, 
> ex-W3WJE (SK), a ham working in pro audio, and Pin One of the 
> connectors used in pro audio is the shield contact.
>
> Before circuit boards, connectors were mounted to the chassis, and 
> most connectors had a shield connection to the shell. Unshielded 
> wiring came through a "feedthrough" capacitor, constructed so that the 
> circuit carried through, with capacitance to the chassis. I'm a very 
> OF that remembers them.
>
> 73, Jim K9YC
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