It is amazing how we were able to build radios with only 2 sided PCBs for 50 ohm micro or strip lines. Come to think of it, it was actually pretty easy.
Hal W7YNC > On 07/30/2025 8:08 PM PDT W3FPR via Elecraft <elecraft@mailman.qth.net> wrote: > > > 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 > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to w3fpr...@gmail.com > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to dyno...@comcast.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
