Re: [Elecraft] [K3] Serial interface noise issues
Thank you Don, that was clear and concise. I'm not an expert on radios or RF like some on this list. I just try to go with what works. I was a firefighter in my previous life. We adapt and overcome. I make things work, then I make them 'pretty'. (Pretty in this case means safer, more reliable and sometimes putting a 'bow on it.) Simple is good; it's often easier and elegant too. We're basically saying the same thing but coming in from different points. Chassis to chassis bonding is wanted, whenever possible. It's not always possible. My old shack laptop has a two wire (ungrounded) mid line wart power connection and bonding the laptop chassis to the station is an exercise in futility (no grounding point on the laptop; the third wire if any, grounds the power supply not the laptop). A desktop chassis should be bonded to the station (yes, as required by code but one size doesn't always fit). And yes, audio 'ground' (return) is rarely chassis ground these days. We agree again though I may have phrased it poorly or used the wrong terms (floating ground) or examples, it was something I was trying to point out. But that is a very common mistake to make too. The two 'grounds' aren't the same and connecting one to the other can cause huge problems, balanced or not. Don't assume that audio ground is chassis ground, it's not that way anymore. Considering the floating pin one problem, that makes many 'ground' wires, (audio return, power, chassis and 'pin 1') each with a different meaning. It'd be easy to presume they're all the same, but they aren't. It makes noise reduction even more difficult. To the original problem of serial data noise: With so much electronics generated RF crud floating around a shack from numerous sources, it's often difficult to find the cause(s) or cure(s) for that noise. Better cables, ferrites, common bonding and similar help but it's a long process to have a quiet shack. A product may meet FCC spec, but be ham lousy with noise. What is working for noise reduction for me (K3, bonded to P3 bonded to KPA500) was moving the antenna farther from the shack and using common mode chokes to keep as much crud off of the feed as I could (reduced by more than 75%). Next was finding quieter laptop power supplies or running off of batteries. I'm still chipping away at the rest (mostly Ethernet CAT 5 wires radiating, switching to WiFi). It has limited success with noise sources not on my property, but its better. And lastly, (then I'll go back to lurking since I'm no expert) when bonding a station to ground (or at least to each other per NEC for those of us in upper stories, not close to dirt or plumbing in the shack), while solid wire meets the NEC code, we're also talking about RF. So braid is best, followed by multi-strand wire, and if nothing else at least a solid #10 wire. Guess what; if you bond for high RF environments, it works to help keep RF in its place and meets the code too (you've exceeded the code with wide braid). Hopefully I was more clear this time. I get the code, concepts and means though I may not state it clearly. Comments, if any, can be made off group, I'm sure the others are tired of this thread. 73, Rick WA6NHC -Original Message- From: Don Wilhelm I will only comment on the part reproduced below - audio return is NOT audio ground. In the case of the Motorola amp cited, I suspect the audio amp output is a bridged amplifier, and for those, neither speaker lead should be grounded (it shorts half of the audio amplifier. BUT, Jim Brown was talking about unbalanced audio inputs, not speaker outputs. In the ham world and the world of consumer audio, most audio inputs are unbalanced, with one conductor (the shield) connected to "ground". That ground used to be the equipment enclosure, but more recent implementations circumvent that and put the connection to the shield onto the PC board rather than the enclosure - and often the enclosure is plastic which creates yet another set of potential problems. We used to connect our audio (and RF) jacks directly to the enclosure and then inside the enclosure, we would route that connection to the circuit contained in that enclosure - no "pin 1" problems because the shield of connected cables were connected first to the outside of the enclosure.. In today's implementations, pin 1 problems abound because jacks for any and every purpose are designed to connect to the PC board and may or may not have any connection to the equipment enclosure. That allows noise and other undesired signals to be introduced onto the device circuit board without being first stripped off by the (grounded) metallic enclosure for the device in question. We have come a long way in convenience for manufacturers, but several problems have occurred along the way, and they are not easy to correct. 73, Don W3FPR __ Elecraft mailing list Home: http:
Re: [Elecraft] [K3] Serial interface noise issues
I will only comment on the part reproduced below - audio return is NOT audio ground. In the case of the Motorola amp cited, I suspect the audio amp output is a bridged amplifier, and for those, neither speaker lead should be grounded (it shorts half of the audio amplifier. BUT, Jim Brown was talking about unbalanced audio inputs, not speaker outputs. In the ham world and the world of consumer audio, most audio inputs are unbalanced, with one conductor (the shield) connected to "ground". That ground used to be the equipment enclosure, but more recent implementations circumvent that and put the connection to the shield onto the PC board rather than the enclosure - and often the enclosure is plastic which creates yet another set of potential problems. We used to connect our audio (and RF) jacks directly to the enclosure and then inside the enclosure, we would route that connection to the circuit contained in that enclosure - no "pin 1" problems because the shield of connected cables were connected first to the outside of the enclosure.. In today's implementations, pin 1 problems abound because jacks for any and every purpose are designed to connect to the PC board and may or may not have any connection to the equipment enclosure. That allows noise and other undesired signals to be introduced onto the device circuit board without being first stripped off by the (grounded) metallic enclosure for the device in question. We have come a long way in convenience for manufacturers, but several problems have occurred along the way, and they are not easy to correct. 73, Don W3FPR On 11/1/2011 9:58 PM, Rick Bates wrote: > In the case of Motorola radios, you'd have to ask them why, but never assume > that either side of a speaker (for example) is chassis grounded, or you'll > blow up a very expensive audio amp (like on the popular GM300). A careful > resistance test should be done before connecting audio ground to chassis. > __ 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] Serial interface noise issues
On 11/1/2011 6:58 PM, Rick Bates wrote: > Not always. It may be considered poor design but if the in/output goes > directly to a differential amp with little or no 'padding' to chassis > (creating the comparison to 'different'), it may have a floating ground and > actually cause problems if connected to ground. You have described a BALANCED input. I'm specifically talking about UNBALANCED inputs and outputs. > In the case of Motorola radios, you'd have to ask them why, but never assume > that either side of a speaker (for example) is chassis grounded, I'm talking about UNBALANCED outputs and inputs for line level interconnects, not loudspeakers. > or you'll > blow up a very expensive audio amp (like on the popular GM300). A careful > resistance test should be done before connecting audio ground to chassis. Such an output should NOT be used to interconnect equipment. > In general, we agree that chassis to chassis bonding SHOULD be encouraged to > reduce noise (and is electrically safer having everything at the same ground > potential). But it does NOT always solve problems. You are badly mistaken. Indeed, NEC REQUIRES that every chassis connected to mains power be bonded to ground, and that ALL grounds be bonded together. > I've seen cases where one (presume a computer to radio) chassis-chassis > connection made the problem worse (ground looped hum), because it introduced > more noise into the radio, even if plugged into the same power source > (should have been equal grounding already). I suggest that you study my tutorial on audio interfacing that is part of my RFI tutorial, and also the Power Point on Ham Interfacing, both of which show WHY power-related noise is coupled into unbalanced interfaces, and WHY chassis-to-chassis bonding kills it, and without the need for a transformer. > Audio isolation transformers > were the solution, pass only the audio. They were YOUR solution, but they are not the only solution, they are not the simplest solution, and they are not the lowest cost solution. > It might be against common practice, but reality trumps theory. Chassis to > chassis grounding may have any range of results (but certainly try it). Not if you do it thoroughly. > And in the case of RF, remember what may be good DC ground isn't always RF > ground. It is a MAJOR mistake to treat audio, RF, and power differently. It is this fuzzy thinking that CAUSES the Pin One Problem, and fails to get to the heart of what is really going on. Again, I suggest that you study my tutorials on this. I'm not just "some guy with an opinion," I'm chair of the Tech Committee on EMC of the Audio Engineering Society, vice-chair of the AES Standards Committee WG on EMC, and principal author of all existing AES Standards on EMC. I had my first job in broadcasting in 1959, and I've designed and used a very wide variety of audio systems, from the very large to the very small, in a wide variety of situations, including VERY high RF environments. In other words, I know quite a bit about the real world. 73, Jim Brown 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
Re: [Elecraft] [K3] Serial interface noise issues
Not always. It may be considered poor design but if the in/output goes directly to a differential amp with little or no 'padding' to chassis (creating the comparison to 'different'), it may have a floating ground and actually cause problems if connected to ground. In the case of Motorola radios, you'd have to ask them why, but never assume that either side of a speaker (for example) is chassis grounded, or you'll blow up a very expensive audio amp (like on the popular GM300). A careful resistance test should be done before connecting audio ground to chassis. In general, we agree that chassis to chassis bonding SHOULD be encouraged to reduce noise (and is electrically safer having everything at the same ground potential). But it does NOT always solve problems. I've seen cases where one (presume a computer to radio) chassis-chassis connection made the problem worse (ground looped hum), because it introduced more noise into the radio, even if plugged into the same power source (should have been equal grounding already). Audio isolation transformers were the solution, pass only the audio. It might be against common practice, but reality trumps theory. Chassis to chassis grounding may have any range of results (but certainly try it). And in the case of RF, remember what may be good DC ground isn't always RF ground. Ask any mobile HF operator (striving to get very low RF resistance to ground to improve antenna efficiency). ;-) With RF, more grounding (overkill) is often MUCH better and always use plenty of low RF resistant metal because of skin effect (braid or at least multi-strand, not solid wire). A lot of the crud generated by electronics is actually low level RF so it should be treated as such. Fortunately, it also works well at DC to audio frequencies as well. Rick WA6NHC -Original Message- From: Jim Brown On 11/1/2011 4:57 PM, Rick Bates wrote: > Note that on some computers, chassis ground is NOT audio ground and I'd > suspect the same is true of some radios (true for at least one of my > Batwings). It SHOULD be. If it is not, the mfr goofed. THAT'S what a Pin One Problem is! Further, unless the audio interface is BALANCED, audio return will always be referenced to the chassis, but it may be a lousy path. > Chassis to chassis bonding may increase noise in that case. WRONG. This is another of those widely held misconceptions that is WRONG. Chassis to chassis bonding is ALWAYS good practice, and ALWAYS minimizes buzz and RFI. __ 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] Serial interface noise issues
On 11/1/2011 4:57 PM, Rick Bates wrote: > Note that on some computers, chassis ground is NOT audio ground and I'd > suspect the same is true of some radios (true for at least one of my > Batwings). It SHOULD be. If it is not, the mfr goofed. THAT'S what a Pin One Problem is! Further, unless the audio interface is BALANCED, audio return will always be referenced to the chassis, but it may be a lousy path. > Chassis to chassis bonding may increase noise in that case. WRONG. This is another of those widely held misconceptions that is WRONG. Chassis to chassis bonding is ALWAYS good practice, and ALWAYS minimizes buzz and RFI. 73, Jim Brown 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
Re: [Elecraft] [K3] Serial interface noise issues
Wall wart power supplies are notorious for creating RF noise (and audible hum). My stock HP laptop power supply generates a vast spectrum of noise but the triple source (wall, 12v, aircraft) replacement is mute on all frequencies, same brand. So part of the test should be removing ALL power sources, not just a shut down or power off. With all the remote controls used these days, it is rare that electronics are really off unless unplugged [also stops parasitic consumption of energy if folks are sensitive about that]. Note that on some computers, chassis ground is NOT audio ground and I'd suspect the same is true of some radios (true for at least one of my Batwings). Chassis to chassis bonding may increase noise in that case. Rick WA6NHC -Original Message- From: Jim Brown On 11/1/2011 3:33 PM, tomb18 wrote: > Do you think that this issuee could still occur with the computer off but the > cable still attached? I have some issues with noise but have attributed > them so far to the power lines. I mean if the cable is picking up > interference from somewhere else, then perhaps this could be an issue? Unlikely, but not impossible. Do the chassis bonding that I recommended -- this is good engineering practice that never hurts, is well known to drastically reduce hum and buzz, and to minimize RFI issues. 73, Jim Brown 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
Re: [Elecraft] [K3] Serial interface noise issues
On 11/1/2011 3:33 PM, tomb18 wrote: > Do you think that this issuee could still occur with the computer off but the > cable still attached? I have some issues with noise but have attributed > them so far to the power lines. I mean if the cable is picking up > interference from somewhere else, then perhaps this could be an issue? Unlikely, but not impossible. Do the chassis bonding that I recommended -- this is good engineering practice that never hurts, is well known to drastically reduce hum and buzz, and to minimize RFI issues. 73, Jim Brown 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
Re: [Elecraft] [K3] Serial interface noise issues
Do you think that this issuee could still occur with the computer off but the cable still attached? I have some issues with noise but have attributed them so far to the power lines. I mean if the cable is picking up interference from somewhere else, then perhaps this could be an issue? I'll have to try disconnecting the cable during a noise spell. -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Serial-interface-noise-issues-tp6951387p6953491.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] Serial interface noise issues
On 11/1/2011 9:54 AM, Jim Brown wrote: > On 11/1/2011 4:51 AM, Thomas Horsten wrote: >> I guess both of these problems could be down to bad/no screening of the >> little chip in the dongle, I tried enclosing it and the cable in kitchen >> foil but with no discernible difference. Any suggestions, > > The more likely cause is a Pin One Problem on one or both ends of the > cable. The only proper termination of a cable shield is to the shielding > enclosure at both ends. I had the same problem when using my K2/100 for RTTY. I had the headphones bridged across the audio output feeding the sound card and I could hear the polling. It sounded like a low pitched "rush ... rush ... rush ..." sort of similar to the ET signal in the movie "Contact" -- only not in prime numbers :-) It was louder when I powered the laptop from the mains, almost disappeared on the battery. It did not show up on the transmitted signal. I switched to the K3 for RTTY, and don't have the problem anymore. 73, Fred K6DGW - Northern California Contest Club - CU in the 2012 Cal QSO Party 6-7 Oct 2012 - www.cqp.org __ 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] Serial interface noise issues
On 11/1/2011 4:51 AM, Thomas Horsten wrote: > I guess both of these problems could be down to bad/no screening of the > little chip in the dongle, I tried enclosing it and the cable in kitchen > foil but with no discernible difference. Any suggestions, The more likely cause is a Pin One Problem on one or both ends of the cable. The only proper termination of a cable shield is to the shielding enclosure at both ends. A Pin One problem, first acknowledged and described in the world of pro audio by Neil Muncy, ex-W3WJE, occurs when the cable shield goes PAST the shielding enclosure to wiring inside the box. This causes any common mode current flowing on the shield to wander around inside the box until it eventually finds a path to the chassis, and from there to "ground." The Problem with this is that, as the current wanders around circuit common inside the box, voltage is dropped across the inductance of the conductors (usually circuit traces) that make up circuit common, and that voltage is injected into the signal path, detected, and amplified. THAT is the Pin One Problem, and it is the most common cause of RFI in today's world. One solution is to FIX the improper wiring, and sometimes that is possible, but often it is not. The other solution is to "put a band-aid" on the Pin One Problem by killing the current that excites it. In the case you describe, the solution is to form a common mode choke by winding 4-6 turns of the serial cable around a #31 or #43 ferrite core made by Fair-Rite. This forms a low-Q parallel resonance in series with the common mode circuit, which looks like a high resistance near resonance. Like any other coil, we put the resonance where we want it by using the "right" number of turns (which sets the inductance) and the "right" spacing between them (which sets the capacitance). The nature of the two ferrite materials I've recommended is that a lot of RESISTANCE is coupled from the lossy ferrite core, so the resonance is VERY low Q (typically about 0.5), and thus very broad. You should also bond between the computer chassis and the K3 chassis using a short conductor. In the US, I would recommend #10 AWG, which is 0.1 inch diameter. This minimizes the hum and buzz produced by leakage currents in the mains power system that also excite the Pin One Problem. The chassis of most laptop computers can be accessed at the retaining screws of a D-connector. For (much) more information on these issues see my various tutorials at http://audiosystemsgroup.com/publish.htm 73, Jim Brown 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
Re: [Elecraft] [K3] Serial interface noise issues
I noticed some noise from the KUSB as well but after playing around a bit discovered that it was being picked up by my nearby temporary antenna setup rather than being conducted or radiated into the K3 directly. Disconnecting the antenna coax killed the noise completely. YMMV Jim ab3cv __ 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] Serial interface noise issues
I use a KUSB from Elecraft and have an increase in noise of 2-3 s-units when used on my lap top. Keith -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Serial-interface-noise-issues-tp6951387p6951837.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 Serial Interface
Hi, Dave! I put this text into the K3 Utility Help on the topic of RS-232 cable requirements: The cable must have a minimum of three wires: Transmit Data, Receive Data, and Ground. Other RS-232 lines (e.g., Request to Send, Clear to Send, Data Set Ready, Data Terminal Ready) are not required to send firmware. The DTR and RTS lines may be used during normal K3 operation for PTT and CW keying. See the Rear Panel and the CONFIG:PTT_KEY sections of the Elecraft K3 Owner's Manual for details. 73 de Dick, K6KR -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Robertson Sent: Friday, May 16, 2008 10:48 AM To: Elecraft Subject: [Elecraft] K3 Serial Interface K3 Owners, In order to download and install new firmware do I need only pin 2 (RXD), Pin 3 (TXD), and Pin 5 (Common or SER C) connected in my serial interface cable from the computer? The schematic shows, in addition to the above, some handshake connections: Pin 7 (RTS) and Pin 4 (DTR). The reason I am asking is I plan to use the Rigblaster Pro to interface with my K3 and Not sure that the serial pass through connection contains the Pin 7 and 4 connections. I have already got successful remote operation with my K2 using the Rigblaster Pro. I am aware that the K2 doesn't use any handshake (Pin 4 and 7) connections for serial interface. Thanks in advance. 73 Dave KD1NA ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 Serial Interface
In order to download and install new firmware do I need only pin 2 (RXD), Pin 3 (TXD), and Pin 5 (Common or SER C) connected in my serial interface cable from the computer? Yes, only these. The schematic shows, in addition to the above, some handshake connections: Pin 7 (RTS) and Pin 4 (DTR). These are for KEY and PTT inputs supported by some programs. They are not used in firmware downloading. 73, Lyle kK7P ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
