Re: [Elecraft] [K3]Advice needed from audio grounding experts
Paul, I think you are looking at the wrong side of the transformer, on the circuit diagram the right hand side connects to the rear panel sockets via J91 and is floating with respect to DC ground. 73 Dave, G4AON According to the schematics one end of the K3 line out isolation transformer is DC grounded and the line in transformer is DC floating (just to be clear I am talking about the windings for external connection). __ 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
Re: [Elecraft] [K3] Advice needed from audio grounding experts
Dave G4AON wrote: Paul, I think you are looking at the wrong side of the transformer, on the circuit diagram the right hand side connects to the rear panel sockets via J91 and is floating with respect to DC ground. Doh. You are quite correct. Thanks for pointing this out Dave. Makes things much simpler. Cheers, Paul. -- View this message in context: http://n2.nabble.com/Re%3A-Advice-needed-from-audio-grounding-experts-tp3449629p3452961.html Sent from the [K3] mailing list archive at Nabble.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
Re: [Elecraft] [K3] Advice needed from audio grounding experts
Paul Fletcher wrote: Dave G4AON wrote: Paul, I think you are looking at the wrong side of the transformer, on the circuit diagram the right hand side connects to the rear panel sockets via J91 and is floating with respect to DC ground. Doh. You are quite correct. Thanks for pointing this out Dave. Makes things much simpler. Note that this list's real expert on audio grounding would claim that the inclusion of the transformers is a design flaw, and the the real solution is good ground bonding and the use of twisted pair cables. Ideally these should have balanced drivers and receiver, but, if I understand him correctly, even unbalanced they help. -- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work. __ 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
[Elecraft] [K3]Advice needed from audio grounding experts
Hi all, I am making up a cable set to connect a Pactor modem to the K3 and wish to avoid ground loops. The connections to the radio are: PTT Power (from the 12v out connector on the back of the K3) Line in Line out According to the schematics one end of the K3 line out isolation transformer is DC grounded and the line in transformer is DC floating (just to be clear I am talking about the windings for external connection). The modem only has 1 ground connection. I obviously need to connect audio out and ground from the modem to the line in on the K3 and this will not provide DC ground. My current thinking is that I connect the modem ground to the 12V ground on the K3 accessory socket to provide the DC ground. Shielded cables would be used for PTT and the connection to the K3 line out with the shield disconnected at the K3 end. Is this the best approach? Regards, Paul M1PAF -- View this message in context: http://n2.nabble.com/-K3-Advice-needed-from-audio-grounding-experts-tp3449586p3449586.html Sent from the Elecraft mailing list archive at Nabble.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
Re: [Elecraft] [K3]Advice needed from audio grounding experts
Hello Paul I took the pre-wired cable that came with my PTC-IIex and terminated the cable in a plastic project box, I connected all 4 of the braid of the screened leads to/from the K3 to the braid of the cable to the SCS modem. The white wire (pin 2 of the DIN plug) on the cable from the modem also connects to the braid at that common point. You might at some stage consider making a switch box to avoid needing to keep swapping those audio plugs when using sound card modes, a cheap 4 pole 3 way rotary switch works well, just needs a few sockets on the rear panel of a small box and you're in business. It saves wear and tear on the rear sockets of the K3. 73 Dave, G4AON K3/100, SCS PTC-IIex - I am making up a cable set to connect a Pactor modem to the K3 and wish to avoid ground loops. The connections to the radio are: __ 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
