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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