Re: [Elecraft] K3 Harmonic Distortion
Rich wrote: I am not an audiologist (?) but isn't a harmonic that is 45db below the fundamental tone essentially non-detectable to normal hearing? Kind of why the harmonics of a RF carrier are to be 40dbs down. The transmitter limits are legislative/engineering compromises. They reflect what is achievable at an acceptable price. For most amateur radio operators, at the receiving end, one would want a limit independent of output power and maybe 10dB below sky noise, in 10 Hz, at the boundary of the transmitting site. Even unintentional transmitters are allowed a lot more than that by the legislation. As transmitters, amateurs would not want such limits, as they would make stations prohibitively expensive, or limited to QRPP. Note that amateurs experiment with ultra-low bandwidth transmissions, so in some case, one might want 10dB below sky noise in 10mHz, or even 1mHz (m used correctly). -- 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 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] K3 Harmonic Distortion
This discussion reminds me of some of the design choices I had to make when designing LP-PAN last year. I wound up using the SP-70 MILSPEC xfmrs, each driven by a pair of op-amps in a push pull configuration with zero ohm source. My original goal was to reduce 2nd harmonic distortion and improve response at frequencies approaching 0 Hz without the need for large capacitors in the output. The xfmrs are quite expensive, even in large quantities, but I have been very happy with the results. Larry N8LP Date: Thu, 04 Sep 2008 14:33:19 -0400 From: Jack Smith [EMAIL PROTECTED] Subject: Re: [Elecraft] K3 Harmonic Distortion To: David Cutter [EMAIL PROTECTED] Cc: elecraft@mailman.qth.net, Leigh L. Klotz, Jr WA5ZNU [EMAIL PROTECTED], Julian, G4ILO [EMAIL PROTECTED] Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; charset=ISO-8859-1; format=flowed David: Even a rather poor transformer improves significantly when driven by a zero ohm source such as an op amp. The typical modem line transformers that are spec'd at 0.5% THD, for example, come in one to two orders of magnitude better when driven by a low impedance source. In fact, it's at the point where my lowest distortion audio generator (HP 200CD) isn't good enough to measure a $4 transformer when driven by an op amp. I'm generator limited at -63 dB at the moment. I hope to improve that measurement floor in the next week or so. Driving the same transformer with a 600 ohm source Z brings you back to the 0.5% THD range. It's all quite interesting and reminds me again that it's not what you don't know that's the problem; rather it's what you think you know that bites you in the backside. Jack ___ 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 Harmonic Distortion
As near as I can see from tracing from one sheet to another, U29, a TLV320ACC23 DAC with integrated headphone amplifier drives the TTC-108 LIN OUT transformers directly. Headphone and speaker audio, in contrast, are derived from a second TLV320 DAC driving a LM4950 amplifier for speaker output and an LM4811 for headphone output... Jack, I am coming into this discussion a bit late, so my apologies to all for any redundancy. I believe the device listed as U29 on the K3 schematic may be a mis-print and my best guess is that's it's the Texas Instruments TLV320AIC23 -- as is the case with U7. The device's H/P output (presumably used for the LINE OUT function) is rated to function down to nearly a zero-ohm load. http://focus.ti.com/lit/ds/slws106d/slws106d.pdf By contrast, the device's line-level output (unused on U29) is specified to function into a Z of no less than 10K-ohm. So, absent any large variation in noise level between the two outputs, Elecraft's choice of using the H/P output was a wise one since the transformers can be driven by a very low-Z. However, currently the TI device is coupled to the transformers with 600-ohm built-out resistors. Once you receive your TTC-108 transformers for testing, it would be an interesting exercise to incrementally change the value of the build-out resistors from a low-Z source -- all the way down to zero, and note the effect of THD/IMD sensitivity as a function of driving source Z. It would be an even more interesting exercise to run the identical test using the Triad transformer you mentioned as well as the Holy Grail of all audio line transformers, a Jensen type. Paul, W9AC -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p841653.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
...I believe the device listed as U29 on the K3 schematic may be a mis-print and my best guess is that's it's the Texas Instruments TLV320AIC23 -- as is the case with U7. The schematic is correct, U29 is a TLV320DAC23. 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
Re: [Elecraft] K3 Harmonic Distortion
Hmmmmy schematic shows TLV320ACC23 for U29. Paul, W9AC - Original Message - From: Lyle Johnson [EMAIL PROTECTED] To: P.B. Christensen [EMAIL PROTECTED] Cc: elecraft@mailman.qth.net Sent: Friday, September 05, 2008 1:22 PM Subject: Re: [Elecraft] K3 Harmonic Distortion ...I believe the device listed as U29 on the K3 schematic may be a mis-print and my best guess is that's it's the Texas Instruments TLV320AIC23 -- as is the case with U7. The schematic is correct, U29 is a TLV320DAC23. 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
Re: [Elecraft] K3 Harmonic Distortion
Paul Christensen wrote: Hmmmmy schematic shows TLV320ACC23 for U29. I see that, too. The D is missing. Lyle ___ 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 Harmonic Distortion
I am not an audiologist (?) but isn't a harmonic that is 45db below the fundamental tone essentially non-detectable to normal hearing? Kind of why the harmonics of a RF carrier are to be 40dbs down. Rich -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p842449.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
On Fri, 5 Sep 2008 17:51:42 -0700 (PDT), Rich wrote: I am not an audiologist (?) but isn't a harmonic that is 45db below the fundamental tone essentially non-detectable to normal hearing? It depends on the order of the harmonic. There are studio processors that INTENTIONALLY generate 2nd harmonic and add it to the signal. The control that adjusts the level is called warmth. :) 3rd order distortion is more audible and more objectionable. Higher orders become increasingly more audible and ojectionable, primarily because they are less musical! BTW -- the science of this is called physhochoacoustics -- the study of how we hear and perceive what we hear, and much is known about it. It is one of many disciplines that are part of the Acoustical Society of America, of which I am a member. 73, Jim K9YC ___ 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 Harmonic Distortion
The measurements that have been made seem to suggest that the problem is not regular distortion or clipping. I am wondering if it is some kind of quantisation effect due to the fact that the signal processing is digital or analog? I am thinking of the fact that there are people who claim that vinyl (analog) LPs sound better than CDs, and FM radio sounds better than DAB. Personally I find it hard to understand what the complaints are about. SSB signals usually have quite a lot of distortion in any case, due to compression and ALC and the fact that they are transmitted through an amplifier whose response would certainly not be described as linear by any hi-fi buff, not to mention any multipath distortion effects introduced by the ionosphere. It's hard to imagine what the K3 could be doing to the signal to make it sound worse. I just don't expect hi-fi audio when listening to the ham bands. Perhaps the K3 is allowing you to hear the original signal warts and all, much as a top-end hi-fi would make recordings that were acceptable on average equipment sound unpleasant? I do find the K3 audio to have rather too good a frequency response, and so on mine I have used the RX equalization to cut the topmost frequency by -16dB and the next one down by -8dB, which to my ears gives a much more restful sound. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p838358.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
This may be a glass half full response but being an old hearing impaired guy has it's positives: 1. Ignoring XYL when needed and excusing it by pointing to hearing aids. 2. Sleeping like a baby every night with said hearing aids removed. 3. Not hearing any distortion in my K3. Life is good 73, Bill NZ0T Julian, G4ILO wrote: The measurements that have been made seem to suggest that the problem is not regular distortion or clipping. I am wondering if it is some kind of quantisation effect due to the fact that the signal processing is digital or analog? I am thinking of the fact that there are people who claim that vinyl (analog) LPs sound better than CDs, and FM radio sounds better than DAB. Personally I find it hard to understand what the complaints are about. SSB signals usually have quite a lot of distortion in any case, due to compression and ALC and the fact that they are transmitted through an amplifier whose response would certainly not be described as linear by any hi-fi buff, not to mention any multipath distortion effects introduced by the ionosphere. It's hard to imagine what the K3 could be doing to the signal to make it sound worse. I just don't expect hi-fi audio when listening to the ham bands. Perhaps the K3 is allowing you to hear the original signal warts and all, much as a top-end hi-fi would make recordings that were acceptable on average equipment sound unpleasant? I do find the K3 audio to have rather too good a frequency response, and so on mine I have used the RX equalization to cut the topmost frequency by -16dB and the next one down by -8dB, which to my ears gives a much more restful sound. -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p838581.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
I haven't done the sort of testing that you must do for your applications, but I've used the OEP8000 transformers in several applications with good results for speech only. I've no idea of its high frequency response. They are tiny in comparison. http://www.oep.co.uk/admin/UploadDocuments/OEP8000.pdf David G3UNA I've ordered a couple of TTC-108 transformers today and will run some experiments with them over the next week or so. I've looked at similar transformers developed for modem and telephone line coupling, but not the TTC-108 specifically, when trying to find a cheaper output transformer to use with the Softrock Lite receivers. There, the emphasis was more on high frequency response, up to 100 KHz, but distortion was also a major issue. The solution of choice in my opinion for the Softrock receivers turns out to be a MILSPEC Triad transformer, SP-70, with excellent frequency response and quite low distortion. In single lot prices, an SD-70 costs about four times as much as a TTC-108. Jack ___ 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] [K3] Harmonic Distortion
The problems people are having with harmonics when they listen to CW with a 2.7KHz filter/DSP setting seem to be easily solved by just reducing the DSP bandwidth. If you were paying attention to the spectrogram plots you would have noticed that the IMD and harmonic products are showing up far outside the bandwidth of the DSP filter, very far. The distortion products are being produced in the analog domain after the DSP digital to analog conversion. No amount of DSP tweaking will fix this. Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 ___ 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 Harmonic Distortion
Julian, The measurements that have been made seem to suggest that the problem is not regular distortion or clipping. I disagree. Every set of measurements I have made shows the speaker and headphone amplifiers in the K3 are very clean right up to the point that they begin to clip. Those who can not get sufficient clean audio should be looking for more efficient headphones or higher power external amplifiers. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Julian, G4ILO Sent: Thursday, September 04, 2008 5:20 AM To: elecraft@mailman.qth.net Subject: RE: [Elecraft] K3 Harmonic Distortion The measurements that have been made seem to suggest that the problem is not regular distortion or clipping. I am wondering if it is some kind of quantisation effect due to the fact that the signal processing is digital or analog? I am thinking of the fact that there are people who claim that vinyl (analog) LPs sound better than CDs, and FM radio sounds better than DAB. Personally I find it hard to understand what the complaints are about. SSB signals usually have quite a lot of distortion in any case, due to compression and ALC and the fact that they are transmitted through an amplifier whose response would certainly not be described as linear by any hi-fi buff, not to mention any multipath distortion effects introduced by the ionosphere. It's hard to imagine what the K3 could be doing to the signal to make it sound worse. I just don't expect hi-fi audio when listening to the ham bands. Perhaps the K3 is allowing you to hear the original signal warts and all, much as a top-end hi-fi would make recordings that were acceptable on average equipment sound unpleasant? I do find the K3 audio to have rather too good a frequency response, and so on mine I have used the RX equalization to cut the topmost frequency by -16dB and the next one down by -8dB, which to my ears gives a much more restful sound. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 ___ 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 Harmonic Distortion
VP8NO writes: Perhaps someone suitably qualified and tooled up might like to try and [repeat] and comment upon the view presented by Rob Sherwood at the Dayton convention. According to him the K3 audio amp stage has serious shortcomings. I had to listen to the audio of Sherwood's talk before looking in the right area. First, Rob doesn't say the K3 audio has serious shortcomings, he complains about distortion on the speaker. Sherwood also admits that using a high impedance speaker (e.g., amplified computer speakers) or high impedance headphones resolves the issue! My measurements did not show that distortion but I was measuring at the headphone output with a high impedance load - the lowest impedance headphones I use are 32 Ohms. As Jack Smith points out, the headphones and the speakers have separate audio amplifiers but share a common DAC. Since Sherwood's comments were based on the speaker output and a LOW impedance load, I dragged out an old Optimus XTX25 speaker - an unpowered 8 Ohm speaker I've used with other radios for many years. With the 8 Ohm speaker is was easy to generate harmonic distortion - particularly if the K3 were set to SPKRS = 2 with only one speaker connected - simply by turning up the volume until the amplifier was forced into clipping/saturation! With the 8 Ohm speaker, 1 to 2V peak represents a comfortable to loud listening level for me. At those levels, the harmonics are all down more than 65 dB and any other distortion is very acceptable. The following table shows harmonic levels relative to a 500 Hz reference tone at the given voltage across the speaker. 0 dB is 1V Peak (.707V RMS). +10 dB represents 2.25V RMS (signal + distortion). +13 dB is 3.2V RMS (the speaker amplifier is in the compression region at the threshold of clipping) and +15 dB is 4V RMS (the speaker amplifier is in hard clipping). Reference2nd 3rd 4th 5th 6th 7th 8th 9th +15 dB -37 -15 -45 -26 -60 -43 -51 -37 +13 dB -49 -31 -51 -35 -57 -39 -63 -49 +10 dB -70 -68 -95 -67 -85 -69 -85 -73 0 dB -66 -74 -70 -77 -73 -76 -77 -80 -10 dB -54 -66 -63 -90 -73 -82 -80 -87 -20 dB -50 -78 -68 -74 -73 -74 -74 -78 In order to drive the audio amplifier hard enough to create the distortion, it was necessary to disable the AGC or set AGC SLP to low values (reduce the AGC reduction for strong signals). Again, as in the case of the Line Out, if the audio gain, AGC and RF gain are operated to keep the speaker amplifier out of the clipping range - or away from the compression region just before clipping - the distortion products are entirely acceptable. For those with noisy shacks, impaired hearing or using the internal speaker it may be difficult to find a comfortable listening level without entering the compression region. For those who wish to operate without AGC and with maximum RF gain, I would suggest setting the AF gain to a moderate level and using powered (computer) speakers or a 100 watt per channel stereo amplifier capable of outputs greater than the 1 watt per channel at .1% THD+N specified for the LM4950 with an 8 Ohm load! Note, simply going from 8 to 16 Ohm speakers will improve THD by 8 dB. 73, ... Joe, W4TV ___ 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 Harmonic Distortion
Clearly I must be missing something. In my view, all the reported distortion numbers are beyond expectations. After all you are buying a $2K radio, not a many kilobuck audio system. The problems people are having with harmonics when they listen to CW with a 2.7KHz filter/DSP setting seem to be easily solved by just reducing the DSP bandwidth. The last resort solution is to get a few years older and you won't hear them. Workarounds for other problems seem to given in the postings. I personally hear and see nothing objectional given the above perspective. 73 de Brian/K3KO Joe Subich, W4TV-3 wrote: VP8NO writes: Perhaps someone suitably qualified and tooled up might like to try and [repeat] and comment upon the view presented by Rob Sherwood at the Dayton convention. According to him the K3 audio amp stage has serious shortcomings. I had to listen to the audio of Sherwood's talk before looking in the right area. First, Rob doesn't say the K3 audio has serious shortcomings, he complains about distortion on the speaker. Sherwood also admits that using a high impedance speaker (e.g., amplified computer speakers) or high impedance headphones resolves the issue! My measurements did not show that distortion but I was measuring at the headphone output with a high impedance load - the lowest impedance headphones I use are 32 Ohms. As Jack Smith points out, the headphones and the speakers have separate audio amplifiers but share a common DAC. Since Sherwood's comments were based on the speaker output and a LOW impedance load, I dragged out an old Optimus XTX25 speaker - an unpowered 8 Ohm speaker I've used with other radios for many years. With the 8 Ohm speaker is was easy to generate harmonic distortion - particularly if the K3 were set to SPKRS = 2 with only one speaker connected - simply by turning up the volume until the amplifier was forced into clipping/saturation! With the 8 Ohm speaker, 1 to 2V peak represents a comfortable to loud listening level for me. At those levels, the harmonics are all down more than 65 dB and any other distortion is very acceptable. The following table shows harmonic levels relative to a 500 Hz reference tone at the given voltage across the speaker. 0 dB is 1V Peak (.707V RMS). +10 dB represents 2.25V RMS (signal + distortion). +13 dB is 3.2V RMS (the speaker amplifier is in the compression region at the threshold of clipping) and +15 dB is 4V RMS (the speaker amplifier is in hard clipping). Reference2nd 3rd 4th 5th 6th 7th 8th 9th +15 dB -37 -15 -45 -26 -60 -43 -51 -37 +13 dB -49 -31 -51 -35 -57 -39 -63 -49 +10 dB -70 -68 -95 -67 -85 -69 -85 -73 0 dB -66 -74 -70 -77 -73 -76 -77 -80 -10 dB -54 -66 -63 -90 -73 -82 -80 -87 -20 dB -50 -78 -68 -74 -73 -74 -74 -78 In order to drive the audio amplifier hard enough to create the distortion, it was necessary to disable the AGC or set AGC SLP to low values (reduce the AGC reduction for strong signals). Again, as in the case of the Line Out, if the audio gain, AGC and RF gain are operated to keep the speaker amplifier out of the clipping range - or away from the compression region just before clipping - the distortion products are entirely acceptable. For those with noisy shacks, impaired hearing or using the internal speaker it may be difficult to find a comfortable listening level without entering the compression region. For those who wish to operate without AGC and with maximum RF gain, I would suggest setting the AF gain to a moderate level and using powered (computer) speakers or a 100 watt per channel stereo amplifier capable of outputs greater than the 1 watt per channel at .1% THD+N specified for the LM4950 with an 8 Ohm load! Note, simply going from 8 to 16 Ohm speakers will improve THD by 8 dB. 73, ... Joe, W4TV ___ 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 -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p836355.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
The problems people are having with harmonics when they listen to CW with a 2.7KHz filter/DSP setting seem to be easily solved by just reducing the DSP bandwidth. Reducing the DSP bandwidth will not resolve the harmonics generated in the speaker amplifier and/or Line Out circuits. The solution is simply not pushing the output gain and keeping the output under 1V peak and use high impedance devices. With the speaker amplifier 800 mW into a 16 Ohm speaker shows less than .01% THD+N - if more audio is necessary 1V peak will easily drive a good quality 100 watt per channel stereo system. With Line Out, 1V peak is plenty for good s/n soundcard operation. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of alsopb Sent: Wednesday, September 03, 2008 9:39 AM To: elecraft@mailman.qth.net Subject: RE: [Elecraft] K3 Harmonic Distortion Clearly I must be missing something. In my view, all the reported distortion numbers are beyond expectations. After all you are buying a $2K radio, not a many kilobuck audio system. The problems people are having with harmonics when they listen to CW with a 2.7KHz filter/DSP setting seem to be easily solved by just reducing the DSP bandwidth. The last resort solution is to get a few years older and you won't hear them. Workarounds for other problems seem to given in the postings. I personally hear and see nothing objectional given the above perspective. 73 de Brian/K3KO Joe Subich, W4TV-3 wrote: VP8NO writes: Perhaps someone suitably qualified and tooled up might like to try and [repeat] and comment upon the view presented by Rob Sherwood at the Dayton convention. According to him the K3 audio amp stage has serious shortcomings. I had to listen to the audio of Sherwood's talk before looking in the right area. First, Rob doesn't say the K3 audio has serious shortcomings, he complains about distortion on the speaker. Sherwood also admits that using a high impedance speaker (e.g., amplified computer speakers) or high impedance headphones resolves the issue! My measurements did not show that distortion but I was measuring at the headphone output with a high impedance load - the lowest impedance headphones I use are 32 Ohms. As Jack Smith points out, the headphones and the speakers have separate audio amplifiers but share a common DAC. Since Sherwood's comments were based on the speaker output and a LOW impedance load, I dragged out an old Optimus XTX25 speaker - an unpowered 8 Ohm speaker I've used with other radios for many years. With the 8 Ohm speaker is was easy to generate harmonic distortion - particularly if the K3 were set to SPKRS = 2 with only one speaker connected - simply by turning up the volume until the amplifier was forced into clipping/saturation! With the 8 Ohm speaker, 1 to 2V peak represents a comfortable to loud listening level for me. At those levels, the harmonics are all down more than 65 dB and any other distortion is very acceptable. The following table shows harmonic levels relative to a 500 Hz reference tone at the given voltage across the speaker. 0 dB is 1V Peak (.707V RMS). +10 dB represents 2.25V RMS (signal + distortion). +13 dB is 3.2V RMS (the speaker amplifier is in the compression region at the threshold of clipping) and +15 dB is 4V RMS (the speaker amplifier is in hard clipping). Reference2nd 3rd 4th 5th 6th 7th 8th 9th +15 dB -37 -15 -45 -26 -60 -43 -51 -37 +13 dB -49 -31 -51 -35 -57 -39 -63 -49 +10 dB -70 -68 -95 -67 -85 -69 -85 -73 0 dB -66 -74 -70 -77 -73 -76 -77 -80 -10 dB -54 -66 -63 -90 -73 -82 -80 -87 -20 dB -50 -78 -68 -74 -73 -74 -74 -78 In order to drive the audio amplifier hard enough to create the distortion, it was necessary to disable the AGC or set AGC SLP to low values (reduce the AGC reduction for strong signals). Again, as in the case of the Line Out, if the audio gain, AGC and RF gain are operated to keep the speaker amplifier out of the clipping range - or away from the compression region just before clipping - the distortion products are entirely acceptable. For those with noisy shacks, impaired hearing or using the internal speaker it may be difficult to find a comfortable listening level without entering the compression region. For those who wish to operate without AGC and with maximum RF gain, I would suggest setting the AF gain to a moderate level and using powered (computer) speakers or a 100 watt per channel stereo amplifier capable of outputs greater than the 1 watt per
RE: [Elecraft] K3 Harmonic Distortion
Joe Subich, W4TV-3 wrote: The solution is simply not pushing the output gain and keeping the output under 1V peak and use high impedance devices. With the speaker amplifier 800 mW into a 16 Ohm speaker shows less than .01% THD+N - if more audio is necessary 1V peak will easily drive a good quality 100 watt per channel stereo system. With Line Out, 1V peak is plenty for good s/n soundcard operation. 73, ... Joe, W4TV The problem I have with all of this is that my K2 doesn't exhibit this issue at all. On my K3 I can clearly hear distortion/harmonics on SSB at moderate volumes through the cans in my Heil headset. In spec or not in spec, it simply shouldn't happen. Elecraft sell the Heil headset marketed for their radios and if headphone impedance mismatch is an issue then surely they wouldn't sell it? A local fellow K3 owner does not hear the effects I hear with the same set up so it's down to hearing response. The issue is real, not everyone hears it. The debate about THD etc. is all valid but regardless of this I still hear it and it drives me nuts. The only solution I've found is to run with the AF gain down when listening on cans which might be OK unless I'm in a noisy environment which is why I'm wearing cans and need to run more gain. The irony of this is that I can avoid the problem when it isn't a problem. Sorry if this has appeared to be a rant but I feel that this is very much a real issue that does not affect everyone. That doesn't mean it shouldn't be addressed. Also, solving the problem by getting closer to my maker is not amusing :-D I waited long enough for the radio in the first place. Cheers, Paul M1PAF -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p837016.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
The spectrum display you sent me shows an excessive level of 50 Hz harmonics - some 15 dB above the noise floor and only 40 dB below the desired signal from 150 Hz to above 3 KHz. That strongly indicates serious grounding issues, power supply filtering problems, improper power supply decoupling and/or soundcard instability. I suggest you read K9YC's information on interfacing and RFI www.audiosystemsgroup.com/publish.htm and resolve that noise issue first. I have seen the K3 audio output go spurious when presented a bad load or encountering regeneration (feedback from powered speakers) due to bad grounds. There is another possible cause of this. The VFO could be being modulated by the magnetic field from an adjoining power supply transformer. I had this happen to me (not with the K3) and the result was a rough sounding note. It's easy to check for - just move the radio as far away from the PSU as it will go. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p833328.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
G'day, Perhaps someone suitably qualified and tooled up might like to try and replicate and comment upon the view presented by Rob Sherwood at the Dayton convention. According to him the K3 audio amp stage has serious shortcomings. Regards, Mike VP8NO - Original Message - From: Jim Brown [EMAIL PROTECTED] To: Elecraft List elecraft@mailman.qth.net Sent: Monday, September 01, 2008 11:45 PM Subject: Re: [Elecraft] K3 Harmonic Distortion | On Mon, 01 Sep 2008 18:45:36 -0400, Jack Smith wrote: | | I've found that the LIN OUT port has typical third harmonic levels | around -45 dB from the fundamental, with the LIN OUT level set at 10, | the factory default. The headphone port, under the same conditions, | will | show the third harmonic down about 70 dB or so at levels appropriate | for | my Sony high sensitivity headphones. Cranking the audio level up will | cause higher distortion on the headphone port, but only at levels that | are impossible to listen to as they are so loud as to be unbearable. | | I've also seen some non-harmonic artifacts, particularly when very | strong signals are pumped into the K3's antenna port. | | Jack, | | I assembled the first of the following reports in June after getting my | first K3 running, and sent privately to the guys at Elecraft. That's why | the new default LIN OUT gain is 10 rather than 50. It's also why there's | a note in the new manual about LIN OUT level. | | http://audiosystemsgroup.com/K3FilterStudy.pdf | | A month or two later, I prepared a report on filters in my Yaesu | FT1000MPs (mostly Inrads) and my K3. | | http://audiosystemsgroup.com/FilterTestNotes.pdf | | This second report describes the test methodology use for the earlier | work, which uses rather a high quality pro audio FFT system (EASERA | SysTun). | | My measurements compare pretty well with yours, but use a very different | measurement method that is not dependent on the distortion of a signal | generator. My method also makes the IM stick out like a sore thumb! | | As you can see from the first graph in the first pdf, distortion at the | headphone output (the black curve) is 0.02% 2nd harmonic, 0.014% 3rd | harmonic, and IM on the order of 0.1%. This was done at about 1 VRMS, | and was done after the LIN OUT measurements without changing levels. | | The only difference between Joe's measurements and mine is that my | analyzer has a bit more resolution, but we're all getting the same | result. The headphone out is VERY VERY VERY good, but the LiN Out starts | producing distortion at a rather low level. BUT, that low level is quite | sufficient to drive a sound card. | | As to the setting of 3 or 10. The distortion is mainly caused by the | output transformer, and distortion in an output transformer increases | rapidly at low frequencies when it approaches its amplitude limit. The | data output is MOSTLY intended for decoding digital signals, especially | RTTY, and the distortion at 2 kHz is a LOT less than at 400 Hz for the | same levels. But distortion is excited not only from signal, but from | noise, and impulse noise can get pretty high. | | Taking all of this into account, I run my LIN OUT gain at 3, and | recommend that setting. | | 73, | | Jim K9YC ___ 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 Harmonic Distortion
Anyway, the noise/distortion is still there coming out of the headphone socket. Berni, this is a technical group and as such we need hard data and not subjective descriptions of what you hear coming out of the headphone jack. I don't doubt that you are hearing something. There is very little I can do with your description however. Please download spectrum analysis software such as Spectrum Laboratory which will give you a way to actually show us some hard data. This is freeware but very capable and will allow you to show us something real. The HRD DM780 is a great tool but it isn't designed to analyze harmonic distortion as you can't measure signal amplitude levels. Here is the download link for spectrum labs. http://freenet-homepage.de/dl4yhf/spectra1.html#download Also, you need to run the input to your sound card from your headphone out jack and not line out if you want to discuss artifacts that you are hearing. If you want to discuss artifacts you are seeing on a waterfall for data modes then run the input to your sound card from the line out. So far your discussion is about what you are hearing but your description of waterfall effects is with line out. These are apples and oranges. Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 ___ 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 Harmonic Distortion
It would be nice to see this problem with the the K3IO board addressed at some point. It may be, as Jim K9YC has hinted, related to core saturation from low frequency components that could attenuated before reaching the board. Or it may be that the transformers that fit in the space are as big as they can be, and a third-party outboard audio amplifier and isolation board is necessary, bypassing the transformers in the K3. But whatever the solution is, I'm looking forward to it, as using PSK with a waterfall display on the K3 requires me to ride the AGC, LIN OUT, and filters in a way that I didn't on the K2. Leigh/WA5ZNU I've found that the LIN OUT port has typical third harmonic levels around -45 dB from the fundamental, with the LIN OUT level set at 10, the factory default. The headphone port, under the same conditions, will show the third harmonic down about 70 dB or so at levels appropriate for my Sony high sensitivity headphones. Cranking the audio level up will cause higher distortion on the headphone port, but only at levels that are impossible to listen to as they are so loud as to be unbearable. I've also seen some non-harmonic artifacts, particularly when very strong signals are pumped into the K3's antenna port. Jack K8ZOA Julian, G4ILO wrote: I think it was me who used the term ghost signals when referring to the harmonically related CW traces I could see on the CW Skimmer display. I probably would have been completely unaware of it if I had never tried this program. It was only obvious as I was listening to CW with a narrow filter and the ghost traces were appearing in the part of the waterfall that you would be expect to be dark because it was outside of the passband. I would agree with the suggestion that the harmonics are at a low level relative to the main signal because they are masked by band noise when you open the filter up. I don't think there is much risk of calling someone on the third harmonic by mistake. I don't know what the voltage level of the line output is but the traces disappear if you turn the level down to 2, which unfortunately is too low for most sound card programs. I don't know if those same harmonics are present on the speaker or headphone outputs, as distinct from the computer audio feed. I can only say that I find the K3 audio exceptionally pleasant to listen to. I much prefer it to the K2, or the FT-817, which are the only other radios I have. The only other radio I have had that sounded as clean and low-distortion as the K3 was an IC-756PRO that I had many years ago. If the harmonics are down by the kind of amounts that others have measured then the distortion figure is still within the specification for what after all is not meant to be an audiophile quality hi-fi output stage. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 ___ 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 Harmonic Distortion
Working through the K3's schematic this morning, it seems that both the headphone output port and the LIN OUT port are driven by similar devices, a Texas Instruments DAC with integrated headphone amplifier. (Two DACs, one for LIN OUT and one for headphones and speaker output.) As near as I can see from tracing from one sheet to another, U29, a TLV320ACC23 DAC with integrated headphone amplifier drives the TTC-108 LIN OUT transformers directly. Headphone and speaker audio, in contrast, are derived from a second TLV320 DAC driving a LM4950 amplifier for speaker output and an LM4811 for headphone output. I've ordered a couple of TTC-108 transformers today and will run some experiments with them over the next week or so. I've looked at similar transformers developed for modem and telephone line coupling, but not the TTC-108 specifically, when trying to find a cheaper output transformer to use with the Softrock Lite receivers. There, the emphasis was more on high frequency response, up to 100 KHz, but distortion was also a major issue. The solution of choice in my opinion for the Softrock receivers turns out to be a MILSPEC Triad transformer, SP-70, with excellent frequency response and quite low distortion. In single lot prices, an SD-70 costs about four times as much as a TTC-108. Jack Leigh L. Klotz, Jr WA5ZNU wrote: It would be nice to see this problem with the the K3IO board addressed at some point. It may be, as Jim K9YC has hinted, related to core saturation from low frequency components that could attenuated before reaching the board. Or it may be that the transformers that fit in the space are as big as they can be, and a third-party outboard audio amplifier and isolation board is necessary, bypassing the transformers in the K3. But whatever the solution is, I'm looking forward to it, as using PSK with a waterfall display on the K3 requires me to ride the AGC, LIN OUT, and filters in a way that I didn't on the K2. Leigh/WA5ZNU I've found that the LIN OUT port has typical third harmonic levels around -45 dB from the fundamental, with the LIN OUT level set at 10, the factory default. The headphone port, under the same conditions, will show the third harmonic down about 70 dB or so at levels appropriate for my Sony high sensitivity headphones. Cranking the audio level up will cause higher distortion on the headphone port, but only at levels that are impossible to listen to as they are so loud as to be unbearable. I've also seen some non-harmonic artifacts, particularly when very strong signals are pumped into the K3's antenna port. Jack K8ZOA Julian, G4ILO wrote: I think it was me who used the term ghost signals when referring to the harmonically related CW traces I could see on the CW Skimmer display. I probably would have been completely unaware of it if I had never tried this program. It was only obvious as I was listening to CW with a narrow filter and the ghost traces were appearing in the part of the waterfall that you would be expect to be dark because it was outside of the passband. I would agree with the suggestion that the harmonics are at a low level relative to the main signal because they are masked by band noise when you open the filter up. I don't think there is much risk of calling someone on the third harmonic by mistake. I don't know what the voltage level of the line output is but the traces disappear if you turn the level down to 2, which unfortunately is too low for most sound card programs. I don't know if those same harmonics are present on the speaker or headphone outputs, as distinct from the computer audio feed. I can only say that I find the K3 audio exceptionally pleasant to listen to. I much prefer it to the K2, or the FT-817, which are the only other radios I have. The only other radio I have had that sounded as clean and low-distortion as the K3 was an IC-756PRO that I had many years ago. If the harmonics are down by the kind of amounts that others have measured then the distortion figure is still within the specification for what after all is not meant to be an audiophile quality hi-fi output stage. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 ___ 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 Harmonic Distortion
Jack I have seen postings on the main reflector recommending settings as low as 3 to avoid distortion products that are being attributed to transformer distortion. This did not really make sense to me, especially at such low levels where consumer sound cards tend to get non-linear and nasty. I took a look at the specifications for the TTC-108 audio transformer used in the line out of the K3 Nominally it's specified as having an operating level of -45dBm to +7dBm THD is specified at 0.5% @0dBm 300Hz to 3.5 Khz @ 0dBm this would make the transformer related harmonics worst case at -46dB relative to the fundamental I did some measurements with an s9 CW signal zero beat at various pitch settings I used an old copy of SMAART pro that I have from my Sound engineering days. the sound card is a delta44 Lin = 100 Pitch 300 pitch 550 pitch 800 DR3 47.3dB 51.4dB 54dB Lin = 50Pitch 300 Pitch 550 Pitch 800 DR3 43.1dB 47.6dB 50.6dB Lin = 10Pitch 300 Pitch 550 Pitch 800 DR3 35dB39.7dB 43.1dB Lin = 5 Pitch 300 Pitch 550 Pitch 800 DR3 31.9dB 37.7dB 42.7dB Lin = 3 Pitch 300 Pitch 550 Pitch 800 DR3 31dB40.3db 47.6dB DR3 is the Dynamic range between the fundamental and the 3rd harmonic (the most dominant harmonic by a wide margin) I did a quick look at 5th and 7th orders too, again the best performance here was found with LIN = 100 LIN = 100 is an output level of approximately 700mv for an S9 CW sig on my K3 The Harmonic distortion does not increase with higher line out levels, it actually improves. This does not appear to be a transformer saturation issue With lin = 100 users will see a ghost on the waterfall and may risk over-driving some consumer sound cards. lowering LIN may get rid of the visible ghost by reducing the 3rd Harmonic to below the waterfall threshold ( perhaps the sound card input noise floor ) but also reduces the overall usable dynamic range 73 Brendan EI6IZ -- Don‘t complain. Nobody will understand. Or care. And certainly don‘t try to fix the situation yourself. It‘s dangerous. Leave it to a highly untrained, unqualified, expendable professional. ___ 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 Harmonic Distortion
On Tue, 02 Sep 2008 11:53:23 -0400, Jack Smith wrote: The solution of choice in my opinion for the Softrock receivers turns out to be a MILSPEC Triad transformer, SP-70, with excellent frequency response and quite low distortion. In single lot prices, an SD-70 costs about four times as much as a TTC-108. You should look at Jensen (www.jensen-transformers.com) and Lundahl (www.lundahl.se) which are pretty much THE standard in the pro audio world. Jensen is well known for excellent applicactions engineering support, with real engineers (not salesmen) answering the questions. Bill Whitlock, the owner, is a Fellow of the AES. The guys who work for him are also very good. Both companies make good, better, and best products, depending on the needs of the installation, but Jensen's best is significantly better than Lundahl's best. The old line mfrs like Triad and UTC are dead meat in the world of pro audio. BTW -- there's another problem with the transformers in the K3 -- they're unshielded, so they pick up whatever magnetic fields surround them. Like the fields from the power transformer(s) for your power amp! This can be either a small problem (hum about -35dB carrier) or hum that regenerates to full transmit power! I have the small problem, my neighbor has the big problem. If you have this problem, you can hear the hum with nothing connected to the line input (if the line input is on). IMO, the transformers need to go away. My Ham Interfacing tutorial shows convincingly why they are completely un-necessary if all the gear in your station is properly bonded together. Leigh Klotz said, It may be, as Jim K9YC has hinted, related to core saturation The most important difference between the Line Out and the Headphone Out IS the transformer and the 600 ohm resistors, and it IS the cause of the much higher distortion on the Line Out. BTW -- 600 ohms has not been good engineering practice in audio for at least 40 years (since the days of TUBES). Modern audio stages have LOW source impedances and HIGH input impedances. 73, Jim Brown K9YC ___ 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 Harmonic Distortion
Brendan: You might wish to look at the measurements I made, with LIN OUT settings from 2 to 100. There's an animated GIF that steps through the LIN OUT settings so you can see the effect. The data was taken at 600 Hz. http://www.cliftonlaboratories.com/elecraft_k3_receive_audio.htm about half way down the page Like you, I see a relatively constant 45 dB or so offset between the fundamental and 3rd harmonic for LIN OUT values of 10 and over. However, setting the LIN OUT at 2 results in quite a bit better odd order harmonic suppression, on the order of nearly 70 dB. By the time LIN OUT is set to 5, however, the odd order suppression is reduced to a bit more than 60 dB. At LIN OUT = 10, it's 45 dB or so where it stays at all values of LIN OUT tested between 10 and 100. (For some reason, the 2nd harmonic pops up at certain settings, but not others higher or lower, but that's not of immediate concern.) There's a related issue with the AGC. The audio output is proportional to RF signal level, as the AGC has a slope to it. Hence, even though the LIN OUT might be set to, say, 2, the actual audio level and hence the distortion, will vary as the RF signal level changes. The degree of audio level variation with RF input changes depends on how the user has set the K3's AGC slope and intercept parameters. I'll make the measurements on a couple of TTC-108 parts when they arrive as a matter of trying to understand where the harmonic distortion arises. To duplicate the K3's audio chain, I'll drive the TTC-108s from an op-amp so that it will be hit with a low Z source, instead of the standard audio generators available to me, with 50 or 600 ohm output Z. Jack Brendan Minish wrote: Jack I have seen postings on the main reflector recommending settings as low as 3 to avoid distortion products that are being attributed to transformer distortion. This did not really make sense to me, especially at such low levels where consumer sound cards tend to get non-linear and nasty. I took a look at the specifications for the TTC-108 audio transformer used in the line out of the K3 Nominally it's specified as having an operating level of -45dBm to +7dBm THD is specified at 0.5% @0dBm 300Hz to 3.5 Khz @ 0dBm this would make the transformer related harmonics worst case at -46dB relative to the fundamental I did some measurements with an s9 CW signal zero beat at various pitch settings I used an old copy of SMAART pro that I have from my Sound engineering days. the sound card is a delta44 Lin = 100 Pitch 300 pitch 550 pitch 800 DR3 47.3dB 51.4dB 54dB Lin = 50Pitch 300 Pitch 550 Pitch 800 DR3 43.1dB 47.6dB 50.6dB Lin = 10Pitch 300 Pitch 550 Pitch 800 DR3 35dB39.7dB 43.1dB Lin = 5 Pitch 300 Pitch 550 Pitch 800 DR3 31.9dB 37.7dB 42.7dB Lin = 3 Pitch 300 Pitch 550 Pitch 800 DR3 31dB40.3db 47.6dB DR3 is the Dynamic range between the fundamental and the 3rd harmonic (the most dominant harmonic by a wide margin) I did a quick look at 5th and 7th orders too, again the best performance here was found with LIN = 100 LIN = 100 is an output level of approximately 700mv for an S9 CW sig on my K3 The Harmonic distortion does not increase with higher line out levels, it actually improves. This does not appear to be a transformer saturation issue With lin = 100 users will see a ghost on the waterfall and may risk over-driving some consumer sound cards. lowering LIN may get rid of the visible ghost by reducing the 3rd Harmonic to below the waterfall threshold ( perhaps the sound card input noise floor ) but also reduces the overall usable dynamic range 73 Brendan EI6IZ ___ 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 Harmonic Distortion
There are three distinct audio channels in the K3, and they all have slightly different characteristics. LINE OUT This has its own digital-to-analog converter (DAC) and is transformer isolated. PHONES This shares a DAC with the speaker channel, but has its own amplifier and isolating resistors to help reduce the impact of plugging in two sets of headphones. SPEAKER This shares a DAC with the headphones, but has its own stereo amplifier. We are aware of the discussions regarding harmonic distortion and IMD. While it is easy to just say, The radio meets specs! (it does :-) we are looking at ways to improve the performance of the entire audio system. 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
Re: [Elecraft] K3 Harmonic Distortion
On Tue, 2008-09-02 at 12:28 -0400, Jack Smith wrote: However, setting the LIN OUT at 2 results in quite a bit better odd order harmonic suppression, on the order of nearly 70 dB. This might be due to simply running out of usable bits to represent accurately the harmonics at the low end of the K3 internal D to A side of things. By the time LIN OUT is set to 5, however, the odd order suppression is reduced to a bit more than 60 dB. At LIN OUT = 10, it's 45 dB or so where it stays at all values of LIN OUT tested between 10 and 100. The issue I have with this is that even with a quiet 24Bit semi Pro card but the time you go to Lin = 2 you are some 40dB down on Full scale input on the sound card assuming Consumer line level Leaving aside all other noise sources this only leaves you with 40 to 50dB or so usable dynamic range. On the other hand if you run near flat out your wanted signal (along with the unwanted harmonics ..) are way above soundcard input amp mixer noise, induced magnetic noise due to the unscreened transformer, Noise picked up internally in the PC etc. This is why I suspect that realworld results will in fact be better at the hotter levels. Visible waterfall ghosts can be resolved by setting your waterfall dynamic range and sensitivity appropriately 73 Brendan EI6IZ -- Don‘t complain. Nobody will understand. Or care. And certainly don‘t try to fix the situation yourself. It‘s dangerous. Leave it to a highly untrained, unqualified, expendable professional. ___ 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 Harmonic Distortion
Date: Tue, 02 Sep 2008 09:34:31 -0700 From: Lyle Johnson [EMAIL PROTECTED] There are three distinct audio channels in the K3, and they all have slightly different characteristics. LINE OUT This has its own digital-to-analog converter (DAC) and is transformer isolated. PHONES This shares a DAC with the speaker channel, but has its own amplifier and isolating resistors to help reduce the impact of plugging in two sets of headphones. SPEAKER This shares a DAC with the headphones, but has its own stereo amplifier. We are aware of the discussions regarding harmonic distortion and IMD. While it is easy to just say, The radio meets specs! (it does :-) we are looking at ways to improve the performance of the entire audio system. And you have lots of help, too!!! I'm sure sorting it all out is sometimes difficult, but 73, doug ___ 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 Harmonic Distortion
There are three distinct stereo audio channels in the K3, and they all have slightly different characteristics. LINE OUT This has its own digital-to-analog converter (DAC) and is transformer isolated. PHONES This shares a DAC with the speaker channel, but has its own amplifier and isolating resistors to help reduce the impact of plugging in two sets of headphones. SPEAKER This shares a DAC with the headphones, but has its own stereo amplifier. We are aware of the discussions regarding harmonic distortion in these audio paths. While it is easy to just say, The radio meets specs! (and it does :-) we are looking at ways to improve the performance of the entire audio system. 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
Re: [Elecraft] K3 Harmonic Distortion
I find virtually the same results here using 50uV RF from an Elecraft signal source, and measuring using Wave Spectra. An offset of 43 to 45dB, and below LIN OUT = 5 the harmonics drop rapidly. 73 Stewart G3RXQ On Tue, 02 Sep 2008 12:28:02 -0400, Jack Smith wrote: Brendan: You might wish to look at the measurements I made, with LIN OUT settings from 2 to 100. There's an animated GIF that steps through the LIN OUT settings so you can see the effect. The data was taken at 600 Hz. http://www.cliftonlaboratories.com/elecraft_k3_receive_audio.htm about half way down the page Like you, I see a relatively constant 45 dB or so offset between the fundamental and 3rd harmonic for LIN OUT values of 10 and over. However, setting the LIN OUT at 2 results in quite a bit better odd order harmonic suppression, on the order of nearly 70 dB. By the time LIN OUT is set to 5, however, the odd order suppression is reduced to a bit more than 60 dB. At LIN OUT = 10, it's 45 dB or so where it stays at all values of LIN OUT tested between 10 and 100. (For some reason, the 2nd harmonic pops up at certain settings, but not others higher or lower, but that's not of immediate concern.) There's a related issue with the AGC. The audio output is proportional to RF signal level, as the AGC has a slope to it. Hence, even though the LIN OUT might be set to, say, 2, the actual audio level and hence the distortion, will vary as the RF signal level changes. The degree of audio level variation with RF input changes depends on how the user has set the K3's AGC slope and intercept parameters. I'll make the measurements on a couple of TTC-108 parts when they arrive as a matter of trying to understand where the harmonic distortion arises. To duplicate the K3's audio chain, I'll drive the TTC-108s from an op-amp so that it will be hit with a low Z source, instead of the standard audio generators available to me, with 50 or 600 ohm output Z. Jack Brendan Minish wrote: Jack I have seen postings on the main reflector recommending settings as low as 3 to avoid distortion products that are being attributed to transformer distortion. This did not really make sense to me, especially at such low levels where consumer sound cards tend to get non-linear and nasty. I took a look at the specifications for the TTC-108 audio transformer used in the line out of the K3 Nominally it's specified as having an operating level of -45dBm to +7dBm THD is specified at 0.5% @0dBm 300Hz to 3.5 Khz @ 0dBm this would make the transformer related harmonics worst case at -46dB relative to the fundamental I did some measurements with an s9 CW signal zero beat at various pitch settings I used an old copy of SMAART pro that I have from my Sound engineering days. the sound card is a delta44 Lin = 100 Pitch 300 pitch 550 pitch 800 DR3 47.3dB 51.4dB 54dB Lin = 50Pitch 300 Pitch 550 Pitch 800 DR3 43.1dB 47.6dB 50.6dB Lin = 10Pitch 300 Pitch 550 Pitch 800 DR3 35dB39.7dB 43.1dB Lin = 5 Pitch 300 Pitch 550 Pitch 800 DR3 31.9dB 37.7dB 42.7dB Lin = 3 Pitch 300 Pitch 550 Pitch 800 DR3 31dB40.3db 47.6dB DR3 is the Dynamic range between the fundamental and the 3rd harmonic (the most dominant harmonic by a wide margin) I did a quick look at 5th and 7th orders too, again the best performance here was found with LIN = 100 LIN = 100 is an output level of approximately 700mv for an S9 CW sig on my K3 The Harmonic distortion does not increase with higher line out levels, it actually improves. This does not appear to be a transformer saturation issue With lin = 100 users will see a ghost on the waterfall and may risk over-driving some consumer sound cards. lowering LIN may get rid of the visible ghost by reducing the 3rd Harmonic to below the waterfall threshold ( perhaps the sound card input noise floor ) but also reduces the overall usable dynamic range 73 Brendan EI6IZ ___ 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 Harmonic Distortion
On Tue, 02 Sep 2008 17:06:29 +0100, Brendan Minish wrote: I used an old copy of SMAART pro that I have from my Sound engineering days. I have that software, and have long used it to analyze ham filters. the sound card is a delta44 I don't know this card, but it's own noise floor (or input stage) may be the limiting factor. Look at the first data set in http://audiosystemsgroup.com/K3FilterStudy.pdf The black curve (the Headphone output) and the red curve (Lin Out) are set to produce the SAME output level, but the harmonic distortion is 55 dB stronger at the Line Output! The difference between the LF traces is IM, and is also significantly greater at the Headphone output. Notice also the dynamic range of this measurement, which is 90 dB. The excitation is band noise, so there's another 10 dB or so between the top of the screen and digital clip. My measurement system is EASERA SysTune (considerably more advanced than Smaart Pro), and the input device is the EASRA Gateway, which has a 24-bit A/D and Firewire interface. I'm fairly confident that the noise floor in my measurements is the radio, not the measurement system! That first data screen shows 3rd harmonic at -55 dB for a gain setting of 1 (and that is the noise floor of the radio). At a gain setting of 2, it's -54 dB. At a gain setting of 3, it's -49 dB. At a gain setting of 5, it's -40 dB. For a setting of 10, it's -28 dB, and at 20, it's - 29 dB. Note also the very significant difference in excitation. My test signal is not a CW signal, but broadband noise from an antenna, band- limited by the IF filters. Your test signal is a sine wave. My test signal is somewhat representative of trying to copy a signal in QRN, or pick one signal out of many in a contest. Your signal is representative of a test bench or a signal with little or no noise on it. As I'm sure you know, those of us working in pro audio find pink noise far more useful than sine waves help us hear real world problems in systems. 73, Jim Brown K9YC ___ 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] [K3] Harmonic Distortion
Taking all of this into account, I run my LIN OUT gain at 3, and recommend that setting. Jim B., I also confirm your analysis with my serial number 508 K3. I don't have your equipment but I was able to see the effects that your well-done reports show. The freeware signal analysis software Spectrum Lab is quite good enough to see the effects and that led me to exact same conclusion, above a gain of 3 the Line Out distortion effects become quite noticeable. I know that LIN OUT and AGC settings might interplay, so for what it is worth I run LIN OUT gain at 3, AGC SLP = 10, AGC THR = 6. Other parameters are default. My sound card gain is now set to maximum. I believe it would be a lot happier if there was more drive. I think maximum soundcard gain with low signal drive makes what ever noise pickup that exists on my cables more obvious as I have a lot of spikes (60-hz multiples) showing outside the filter pass band just 18 dB below the general tops of the in-band noise spectrum. Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 ___ 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] Harmonic Distortion
On Tue, 2 Sep 2008 11:36:19 -0700, Mike Scott wrote: I know that LIN OUT and AGC settings might interplay, Yes. so for what it is worth I run LIN OUT gain at 3, AGC SLP = 10, AGC THR = 6. Other parameters are default. I haven't studied what the ideal settings are, but I would follow Lyle's guidelines for strong signal conditions. My sound card gain is now set to maximum. I believe it would be a lot happier if there was more drive. I think maximum soundcard gain with low signal drive makes what ever noise pickup that exists on my cables more obvious as I have a lot of spikes (60-hz multiples) showing outside the filter pass band just 18 dB below the general tops of the in-band noise spectrum. See my Power Point on how to kill this noise by bonding together the chassis of the computer to the chassis of the rig. It's easy, cheap, and very effective. http://audiosystemsgroup.com/HamInterfacing.pdf and the same stuff as text in http://audiosystemsgroup.com/RFI-Ham.pdf 73, Jim K9YC ___ 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 Harmonic Distortion
Hi Lyle, only to be sure - if I have in CONFIG: LINE OUT - PHONES which D/A is used - this one for SP/PHONES ? Then LINE OUT level is controlled by AF knob so I suppose that PH/SP channel is used but not sure. Thanks Lexa, OK1DST Lyle Johnson napsal(a): There are three distinct stereo audio channels in the K3, and they all have slightly different characteristics. LINE OUT This has its own digital-to-analog converter (DAC) and is transformer isolated. PHONES This shares a DAC with the speaker channel, but has its own amplifier and isolating resistors to help reduce the impact of plugging in two sets of headphones. SPEAKER This shares a DAC with the headphones, but has its own stereo amplifier. We are aware of the discussions regarding harmonic distortion in these audio paths. While it is easy to just say, The radio meets specs! (and it does :-) we are looking at ways to improve the performance of the entire audio system. 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 ___ 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 Harmonic Distortion
only to be sure - if I have in CONFIG: LINE OUT - PHONES which D/A is used - this one for SP/PHONES ? LINE OUT is always driven by the LINE OUT DAC. 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
RE: [Elecraft] K3 Harmonic Distortion
The issue isn't the LINE OUT level, it is the voltage level. If you leave the AGC on and AGC SLP 11 the voltage with an S9 (-73 dBm) signal will not exceed 1V peak (.77 V RMS) and you will not see distortion products through the transformer. If you set turn of the AGC an/or set AGC SLP 10, the transformers (or audio amplifier) can be easily overdriven and the distortion products will rise significantly - even to the point that harmonics through the 10th or higher are down less than 10 dB. With the line out the entire issue is keeping LINE OUT below 1V Peak. There are other sues with the headphone and speaker output and I'll address them elsewhere. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stewart Baker Sent: Tuesday, September 02, 2008 12:59 PM To: Jack Smith; Brendan Minish Cc: Elecraft Subject: Re: [Elecraft] K3 Harmonic Distortion I find virtually the same results here using 50uV RF from an Elecraft signal source, and measuring using Wave Spectra. An offset of 43 to 45dB, and below LIN OUT = 5 the harmonics drop rapidly. 73 Stewart G3RXQ On Tue, 02 Sep 2008 12:28:02 -0400, Jack Smith wrote: Brendan: You might wish to look at the measurements I made, with LIN OUT settings from 2 to 100. There's an animated GIF that steps through the LIN OUT settings so you can see the effect. The data was taken at 600 Hz. http://www.cliftonlaboratories.com/elecraft_k3_receive_audio.htm about half way down the page Like you, I see a relatively constant 45 dB or so offset between the fundamental and 3rd harmonic for LIN OUT values of 10 and over. However, setting the LIN OUT at 2 results in quite a bit better odd order harmonic suppression, on the order of nearly 70 dB. By the time LIN OUT is set to 5, however, the odd order suppression is reduced to a bit more than 60 dB. At LIN OUT = 10, it's 45 dB or so where it stays at all values of LIN OUT tested between 10 and 100. (For some reason, the 2nd harmonic pops up at certain settings, but not others higher or lower, but that's not of immediate concern.) There's a related issue with the AGC. The audio output is proportional to RF signal level, as the AGC has a slope to it. Hence, even though the LIN OUT might be set to, say, 2, the actual audio level and hence the distortion, will vary as the RF signal level changes. The degree of audio level variation with RF input changes depends on how the user has set the K3's AGC slope and intercept parameters. I'll make the measurements on a couple of TTC-108 parts when they arrive as a matter of trying to understand where the harmonic distortion arises. To duplicate the K3's audio chain, I'll drive the TTC-108s from an op-amp so that it will be hit with a low Z source, instead of the standard audio generators available to me, with 50 or 600 ohm output Z. Jack Brendan Minish wrote: Jack I have seen postings on the main reflector recommending settings as low as 3 to avoid distortion products that are being attributed to transformer distortion. This did not really make sense to me, especially at such low levels where consumer sound cards tend to get non-linear and nasty. I took a look at the specifications for the TTC-108 audio transformer used in the line out of the K3 Nominally it's specified as having an operating level of -45dBm to +7dBm THD is specified at 0.5% @0dBm 300Hz to 3.5 Khz @ 0dBm this would make the transformer related harmonics worst case at -46dB relative to the fundamental I did some measurements with an s9 CW signal zero beat at various pitch settings I used an old copy of SMAART pro that I have from my Sound engineering days. the sound card is a delta44 Lin = 100 Pitch 300 pitch 550 pitch 800 DR3 47.3dB 51.4dB 54dB Lin = 50Pitch 300 Pitch 550 Pitch 800 DR3 43.1dB 47.6dB 50.6dB Lin = 10Pitch 300 Pitch 550 Pitch 800 DR3 35dB39.7dB 43.1dB Lin = 5 Pitch 300 Pitch 550 Pitch 800 DR3 31.9dB 37.7dB 42.7dB Lin = 3 Pitch 300 Pitch 550 Pitch 800 DR3 31dB40.3db 47.6dB DR3 is the Dynamic range between the fundamental and the 3rd harmonic (the most dominant harmonic by a wide margin) I did a quick look at 5th and 7th orders too, again the best performance here was found with LIN = 100 LIN = 100 is an output level of approximately 700mv for an S9 CW sig on my K3 The Harmonic distortion does not increase with higher line out levels, it actually improves. This does not appear to be a transformer saturation issue With lin = 100 users will see a ghost
Re: [Elecraft] K3 Harmonic Distortion
In my previous posting I referenced to a couple of plots I made of the Line output using a wideband RF noise source I put the 2 plots on my blog here http://ei6iz.com/?p=22 73 Brendan EI6IZ -- Don‘t complain. Nobody will understand. Or care. And certainly don‘t try to fix the situation yourself. It‘s dangerous. Leave it to a highly untrained, unqualified, expendable professional. ___ 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] {K3} Harmonic Distortion
While I appreciate all the deep comments about K3 audio, I do need to report that transformers are an effective way to eliminate hum in a less-than-ideal installation. I have used cheap Radio Shack audio transformers for years to allow my transceivers of all stripes to operate on PSK31 and other computer modes. I APPRECIATE THEIR PRESENCE IN THE K3! I was able to fire up and operate PSK31, SSTV, RTTY with only a couple of cable connections. This is nice. I obviously am a dilettante operator, not a contester. Since my antenna is way suboptimal, I do not worry about a few db in the audio chain. ___ 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] K3 Harmonic Distortion
Hi Everyone, I'm re doing the thread as this time I have some concrete findings to share with you and wail be writing to Elecraft about this problem. My previous thread was about ringing in the audio but now it is harmonic distortion at three times the frequency. I went around M0GJH's house house with my K3 and put it side by side with his. I found the same distortion by listening on his radio too. A CW signal (as well as SSB) sounds a bit distorted and so we put the output into his PC which was running Ham Radio Deluxe DM780 with a waterfall display. Here you could quite clearly see that at 3 times any CW signal a signal was present and was beating with the fundamental causing distortion. The bandwidth was set to 1.5KHz and NR off. In fact with NR in there was no difference of the 3rd harmonic it was still there and very noticeable. Fundamental frequency received = 800Hz, Harmonic on waterfall display = 2400Hz. The RX EQ was set to flat. Mode used was CW. Line out from the back was used. Andrew M0GJH had mainly presumed that signals which sounded a bit rough were due to the station sending but in fact and it is my belief that there is a problem with the K3 be it in the audio section or DSP this I do not know as I don't have the knowledge. I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. Cheers, Berni G0IDA #1474 -- ___ 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 Harmonic Distortion
I will also try two simultaneous signals and see if I can duplicate your mixing observations. Jack K8ZOA Berni G0IDA wrote: Hi Everyone, I'm re doing the thread as this time I have some concrete findings to share with you and wail be writing to Elecraft about this problem. My previous thread was about ringing in the audio but now it is harmonic distortion at three times the frequency. I went around M0GJH's house house with my K3 and put it side by side with his. I found the same distortion by listening on his radio too. A CW signal (as well as SSB) sounds a bit distorted and so we put the output into his PC which was running Ham Radio Deluxe DM780 with a waterfall display. Here you could quite clearly see that at 3 times any CW signal a signal was present and was beating with the fundamental causing distortion. The bandwidth was set to 1.5KHz and NR off. In fact with NR in there was no difference of the 3rd harmonic it was still there and very noticeable. Fundamental frequency received = 800Hz, Harmonic on waterfall display = 2400Hz. The RX EQ was set to flat. Mode used was CW. Line out from the back was used. Andrew M0GJH had mainly presumed that signals which sounded a bit rough were due to the station sending but in fact and it is my belief that there is a problem with the K3 be it in the audio section or DSP this I do not know as I don't have the knowledge. I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. Cheers, Berni G0IDA #1474 ___ 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 Harmonic Distortion
On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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 Harmonic Distortion
Jim None of those things helps. I can reduce my LINE OUT gain to 1 and still see the 3rd harmonic easily on the waterfall. I've had many rigs and this is the first to do this. There was a thread about this not long ago. Do a nabble search on ghost. There is also some distortion in the speaker output but I'm told that this is a separate amplifier. Steve Ellington [EMAIL PROTECTED] - Original Message - From: Jim Brown [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Monday, September 01, 2008 12:05 PM Subject: Re: [Elecraft] K3 Harmonic Distortion On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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 No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.169 / Virus Database: 270.6.14/1645 - Release Date: 9/1/2008 7:19 AM ___ 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 Harmonic Distortion
Jim is entirely correct although we will disagree a bit about the need to keep the line out as low as he suggests. My own measurements say the harmonic distortion is insignificant as long as the Line Out levels stay below .5V RMS. The headphone outputs are exceptionally clean as long as the audio amplifier level is kept below 2V peak (1.4V RMS) and the output impedance is not too low. In fact, noise in the audio amplifier (headphones) is 70 dB below the desired (CW at 500 Hz) signal +/- 250 Hz and 80 dB below the desired signal above that. All harmonics are down more than 60 dB as long as the headphone level is not at levels that could damage hearing ( 1.4V RMS). The headphone output in the K3 is cleaner than any amateur receiver I have seen and certainly better than the current crop from Ikensu or Yaecomwood. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Brown Sent: Monday, September 01, 2008 12:06 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 Harmonic Distortion On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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 Harmonic Distortion
None of those things helps. I can reduce my LINE OUT gain to 1 and still see the 3rd harmonic easily on the waterfall. I've had many rigs and this is the first to do this. Turn on the ACG and make sure the audio level from your Line Out does not exceed .7V RMS. As long as the AGC is on, I can turn my Line Out to 100 and not see any ghost except the 3rd harmonic on the waterfall in Digipan. An AF spectrum analyzer shows the 3rd Harmonic about -50 dB and others below that. If you insist on running with AGC off or low values of SGC SLP, TURN DOWN the RF gain to keep from overdriving the Line Out amp and transformers. Any reasonable soundcard should operate very happily with 200 to 500 mV RMS - well within the linear capability of the Line Out amp and transformers. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of n4lq Sent: Monday, September 01, 2008 12:14 PM To: Jim Brown; elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 Harmonic Distortion Jim None of those things helps. I can reduce my LINE OUT gain to 1 and still see the 3rd harmonic easily on the waterfall. I've had many rigs and this is the first to do this. There was a thread about this not long ago. Do a nabble search on ghost. There is also some distortion in the speaker output but I'm told that this is a separate amplifier. Steve Ellington [EMAIL PROTECTED] - Original Message - From: Jim Brown [EMAIL PROTECTED] To: elecraft@mailman.qth.net Sent: Monday, September 01, 2008 12:05 PM Subject: Re: [Elecraft] K3 Harmonic Distortion On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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 -- -- No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.169 / Virus Database: 270.6.14/1645 - Release Date: 9/1/2008 7:19 AM ___ 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 Harmonic Distortion
On Mon, 1 Sep 2008 12:38:31 -0400, Joe Subich, W4TV wrote: Jim is entirely correct although we will disagree a bit about the need to keep the line out as low as he suggests. My own measurements say the harmonic distortion is insignificant as long as the Line Out levels stay below .5V RMS. Insignificant depends on the decoder, what you are decoding (PSK or RTTY), band conditions, and the operator. If a PSK operator is using the IF with a broadband setting and tries to work a signal that's really a harmonic, it won't work -- he'll be transmitting on a frequency displaced from the signal he thinks he's working (displaced by 2X the audio frequency of the actual signal if it's a third harmonic, 1X if it't the second harmonic). If it's a crowded RTTY contest, there can be lots of big signals creating that IM. Or the operator could be using a narrow roofing filter and those other signals are not there or heavily suppressed, so can't cause IM. The headphone outputs are exceptionally clean as long as the audio amplifier level is kept below 2V peak (1.4V RMS) and the output impedance is not too low. In fact, noise in the audio amplifier (headphones) is 70 dB below the desired (CW at 500 Hz) signal +/- 250 Hz and 80 dB below the desired signal above that. All harmonics are down more than 60 dB as long as the headphone level is not at levels that could damage hearing ( 1.4V RMS). YES! My measurements of the headphone output, taken at about 1 volt RMS, show harmonic distortion at about 0.02% and IM at less than 0.1%. That is VERY VERY good! 1VRMS is LOUD! The headphone output in the K3 is cleaner than any amateur receiver I have seen and certainly better than the current crop from Ikensu or Yaecomwood. Yes. 73, Jim ___ 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 Harmonic Distortion
Thanks everyone for the replies. I just would like to put this thread back onto its tracks. The problem is with CW (although SSB does suffer too) and the main problem is that I can hear the 3rd harmonic which when mixed with the fundamental makes a rough note on CW especially when tuning away going up in frequency. I only used the waterfall program to confirm and to see at which harmonic it occurred and line levels, AGC, PC cards etc...etc... have no baring on this as I'm not measuring anything, just confirming that it is there. I compared 2 K3s and both had the same effect. I'm using a Hiel headset to listen to CW it is also noticeable on the main speaker but less so due to its design. When confirming on the waterfall and indeed with my ears the rig is at default setting no amount of tweaking helps. Even with 1KHz of filtering a 3rd harmonic is present. K9YC: 1) Yes 2) Line level is irrelevant as I'm just confirming that it is there and at which harmonic so as to give feedback to the reflector. 3) as above. N4LQ: I agree with you, nothing seems to help and I've never had this with the FT1000MP or my recent Mk v. W4TV: I envy the K3 you have as there is 3rd product distortion and never had this on any other rig... could there be a bad batch or K3s? Just like to re-iterate that the thread is not about how to set up your PC/LINE OUT or IN not to get distortion, it is about 3rd harmonic distortion present on the headphone socket and speaker with or without default settings! Jim: PSK + RTTY might have its own problems its not part of my discussion, I'm trying to concentrate this thread on just one mode CW where this problem is significant as at times it is unpleasant to listen to. SSB also has this unpleasant distortion. There is one option a friend suggested wait until I get older and the hearing drops off in frequency at the moment it seems the only option..hi..hi..hi.. 73s Berni G0IDA Jim Brown wrote: On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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 Harmonic Distortion
I've made a number of measurements on the K3's audio output a few days ago in CW mode and again today, this time with two close spaced signals inside the SSB filter as well as a single tone. Yes, there are 3rd and other odd-order harmonics and, to a lesser degree, even order harmonics. However, these harmonics are down between 45 and 50 dB from the desired signal in most instances. That's quite a bit of odd order harmonic suppression, well under 1% THD. I can see intermodulation products and in-band artifacts with the AGC on and quite strong signal levels. These are also quite a bit down from the two tones, but certainly differ from the same signal levels applied to a receiver with analog detection stages. I cannot hear an objectionable beat note or rough audio, but I'm afraid that I fall into the category of being old enough to not have great high frequency hearing. I'll put some of the audio spectrum analyzer captures up on my web site later today or tomorrow. Jack K8ZOA Berni G0IDA wrote: Thanks everyone for the replies. I just would like to put this thread back onto its tracks. The problem is with CW (although SSB does suffer too) and the main problem is that I can hear the 3rd harmonic which when mixed with the fundamental makes a rough note on CW especially when tuning away going up in frequency. I only used the waterfall program to confirm and to see at which harmonic it occurred and line levels, AGC, PC cards etc...etc... have no baring on this as I'm not measuring anything, just confirming that it is there. I compared 2 K3s and both had the same effect. I'm using a Hiel headset to listen to CW it is also noticeable on the main speaker but less so due to its design. When confirming on the waterfall and indeed with my ears the rig is at default setting no amount of tweaking helps. Even with 1KHz of filtering a 3rd harmonic is present. K9YC: 1) Yes 2) Line level is irrelevant as I'm just confirming that it is there and at which harmonic so as to give feedback to the reflector. 3) as above. N4LQ: I agree with you, nothing seems to help and I've never had this with the FT1000MP or my recent Mk v. W4TV: I envy the K3 you have as there is 3rd product distortion and never had this on any other rig... could there be a bad batch or K3s? Just like to re-iterate that the thread is not about how to set up your PC/LINE OUT or IN not to get distortion, it is about 3rd harmonic distortion present on the headphone socket and speaker with or without default settings! Jim: PSK + RTTY might have its own problems its not part of my discussion, I'm trying to concentrate this thread on just one mode CW where this problem is significant as at times it is unpleasant to listen to. SSB also has this unpleasant distortion. There is one option a friend suggested wait until I get older and the hearing drops off in frequency at the moment it seems the only option..hi..hi..hi.. 73s Berni G0IDA Jim Brown wrote: On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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 Harmonic Distortion
Berni G0IDA wrote: I just would like to put this thread back onto its tracks. The problem is with CW (although SSB does suffer too) and the main problem is that I can hear the 3rd harmonic which when mixed with the fundamental makes a rough note on CW especially when tuning away going up in frequency. Combining third and fundamental, at AF, should not produce a rough note. It should produce a string-like tone rather than the flute-like done from just the fundamental. If you are getting any low frequency beat, it means the signals are not harmonically related. (I think you would need an awful lot of third harmonic to shift much from flute to string.) -- David Woolley The Elecraft list is a forum for the discussion of topics related to Elecraft products and more general topics related ham radio List Guidelines http://www.elecraft.com/elecraft_list_guidelines.htm ___ 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 Harmonic Distortion
I think it was me who used the term ghost signals when referring to the harmonically related CW traces I could see on the CW Skimmer display. I probably would have been completely unaware of it if I had never tried this program. It was only obvious as I was listening to CW with a narrow filter and the ghost traces were appearing in the part of the waterfall that you would be expect to be dark because it was outside of the passband. I would agree with the suggestion that the harmonics are at a low level relative to the main signal because they are masked by band noise when you open the filter up. I don't think there is much risk of calling someone on the third harmonic by mistake. I don't know what the voltage level of the line output is but the traces disappear if you turn the level down to 2, which unfortunately is too low for most sound card programs. I don't know if those same harmonics are present on the speaker or headphone outputs, as distinct from the computer audio feed. I can only say that I find the K3 audio exceptionally pleasant to listen to. I much prefer it to the K2, or the FT-817, which are the only other radios I have. The only other radio I have had that sounded as clean and low-distortion as the K3 was an IC-756PRO that I had many years ago. If the harmonics are down by the kind of amounts that others have measured then the distortion figure is still within the specification for what after all is not meant to be an audiophile quality hi-fi output stage. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p832695.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
Jim, Insignificant depends on the decoder, what you are decoding (PSK or RTTY), band conditions, and the operator. If a PSK operator is using the IF with a broadband setting and tries to work a signal that's really a harmonic, it won't work -- he'll be transmitting on a frequency displaced from the signal he thinks he's working (displaced by 2X the audio frequency of the actual signal if it's a third harmonic, 1X if it't the second harmonic). If it's a crowded RTTY contest, there can be lots of big signals creating that IM. Or the operator could be using a narrow roofing filter and those other signals are not there or heavily suppressed, so can't cause IM. It would be a sorry situation if an operator can't tell the difference between a desired signal and an audio harmonic down 50 dB. K3_Line_out.jpg shows the line out spectrum of my K3 at 1 KHz, Data_A, 2.8 KHz 1st IF filter and 4 KHz filter. The third harmonic is -62 dB and the fifth harmonic is - 80 dB. See: www.microHAM-USA.com/Downloads/K3_Line_Out.jpg. A typical waterfall does not show the spurious signals at the soundcard input (noise on the cables) which is well below the band noise - typically around -60 dBu. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Brown Sent: Monday, September 01, 2008 1:33 PM To: elecraft@mailman.qth.net Subject: RE: [Elecraft] K3 Harmonic Distortion On Mon, 1 Sep 2008 12:38:31 -0400, Joe Subich, W4TV wrote: Jim is entirely correct although we will disagree a bit about the need to keep the line out as low as he suggests. My own measurements say the harmonic distortion is insignificant as long as the Line Out levels stay below .5V RMS. Insignificant depends on the decoder, what you are decoding (PSK or RTTY), band conditions, and the operator. If a PSK operator is using the IF with a broadband setting and tries to work a signal that's really a harmonic, it won't work -- he'll be transmitting on a frequency displaced from the signal he thinks he's working (displaced by 2X the audio frequency of the actual signal if it's a third harmonic, 1X if it't the second harmonic). If it's a crowded RTTY contest, there can be lots of big signals creating that IM. Or the operator could be using a narrow roofing filter and those other signals are not there or heavily suppressed, so can't cause IM. The headphone outputs are exceptionally clean as long as the audio amplifier level is kept below 2V peak (1.4V RMS) and the output impedance is not too low. In fact, noise in the audio amplifier (headphones) is 70 dB below the desired (CW at 500 Hz) signal +/- 250 Hz and 80 dB below the desired signal above that. All harmonics are down more than 60 dB as long as the headphone level is not at levels that could damage hearing ( 1.4V RMS). YES! My measurements of the headphone output, taken at about 1 volt RMS, show harmonic distortion at about 0.02% and IM at less than 0.1%. That is VERY VERY good! 1VRMS is LOUD! The headphone output in the K3 is cleaner than any amateur receiver I have seen and certainly better than the current crop from Ikensu or Yaecomwood. Yes. 73, Jim ___ 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 Harmonic Distortion
W4TV: I envy the K3 you have as there is 3rd product distortion and never had this on any other rig... could there be a bad batch or K3s? Just like to re-iterate that the thread is not about how to set up your PC/LINE OUT or IN not to get distortion, it is about 3rd harmonic distortion present on the headphone socket and speaker with or without default settings! My point is that my K3 - s/n 622 (factory assembled) has absolutely no measurable harmonics on the headphone output unless I force the gain to a painful level. I use external speakers (two) but have made my measurements from the headphone jack (left) - I have checked with both SPKRS=2 and SPKRS=1 as well as SPKR+PH in both Yes and No. I have also checked with all AFX options and see no difference. Two sample Audio Spectrum plots are attached or may be downloaded at: www.microHAM-USA.com/Downloads/K3_Headphone_No_Signal.jpg and: www.microHAM-USA.com/Downloads/K3_Headphone_out.jpg. The Headphone Out capture is of an S-9 signal (1KHz audio) in DATA_A mode with AGC On, 2.8 KHz 1st IF filter and 2.8 KHz DSP bandwidth. This shows signal at 70 dB above the noise floor, second harmonic at -73 dB and third harmonic at -81 dB with no intermodulation. I made similar measurements at 500 Hz in data mode and again all harmonic and distortion products are down more than 60 dB. To confirm that the issue was not one that was present only in CW mode, I also made measurements at 500 Hz and 800 Hz in CW - again. 2nd, 3rd, 4th, 6th, 8th and 10th harmonics were visible in the I will make similar measurements with a second K3 (s/n 1450) and KRX3 when I finish assembly. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Berni G0IDA Sent: Monday, September 01, 2008 3:20 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 Harmonic Distortion Thanks everyone for the replies. I just would like to put this thread back onto its tracks. The problem is with CW (although SSB does suffer too) and the main problem is that I can hear the 3rd harmonic which when mixed with the fundamental makes a rough note on CW especially when tuning away going up in frequency. I only used the waterfall program to confirm and to see at which harmonic it occurred and line levels, AGC, PC cards etc...etc... have no baring on this as I'm not measuring anything, just confirming that it is there. I compared 2 K3s and both had the same effect. I'm using a Hiel headset to listen to CW it is also noticeable on the main speaker but less so due to its design. When confirming on the waterfall and indeed with my ears the rig is at default setting no amount of tweaking helps. Even with 1KHz of filtering a 3rd harmonic is present. K9YC: 1) Yes 2) Line level is irrelevant as I'm just confirming that it is there and at which harmonic so as to give feedback to the reflector. 3) as above. N4LQ: I agree with you, nothing seems to help and I've never had this with the FT1000MP or my recent Mk v. W4TV: I envy the K3 you have as there is 3rd product distortion and never had this on any other rig... could there be a bad batch or K3s? Just like to re-iterate that the thread is not about how to set up your PC/LINE OUT or IN not to get distortion, it is about 3rd harmonic distortion present on the headphone socket and speaker with or without default settings! Jim: PSK + RTTY might have its own problems its not part of my discussion, I'm trying to concentrate this thread on just one mode CW where this problem is significant as at times it is unpleasant to listen to. SSB also has this unpleasant distortion. There is one option a friend suggested wait until I get older and the hearing drops off in frequency at the moment it seems the only option..hi..hi..hi.. 73s Berni G0IDA Jim Brown wrote: On Mon, 01 Sep 2008 14:30:45 +0100, Berni G0IDA wrote: I hope there is a cure for this as it's frustrating listening to CW with this sort of distortion. There are three things you should do. 1) Make sure that the AGC is on, and that the CONFIG AGC settings are at the defaults. 2) Reduce the LINEOUT GAIN (on the CONFIG menu) to a value less than about 4. This prevents distortion that could occur in the output transformer. 3) Adjust the input gain of your computer so that you have enough signal for the decoder to function, but not enough to cause distortion. This should correct any problems. 73, Jim K9YC ___ 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
Re: [Elecraft] K3 Harmonic Distortion
I've found that the LIN OUT port has typical third harmonic levels around -45 dB from the fundamental, with the LIN OUT level set at 10, the factory default. The headphone port, under the same conditions, will show the third harmonic down about 70 dB or so at levels appropriate for my Sony high sensitivity headphones. Cranking the audio level up will cause higher distortion on the headphone port, but only at levels that are impossible to listen to as they are so loud as to be unbearable. I've also seen some non-harmonic artifacts, particularly when very strong signals are pumped into the K3's antenna port. Jack K8ZOA Julian, G4ILO wrote: I think it was me who used the term ghost signals when referring to the harmonically related CW traces I could see on the CW Skimmer display. I probably would have been completely unaware of it if I had never tried this program. It was only obvious as I was listening to CW with a narrow filter and the ghost traces were appearing in the part of the waterfall that you would be expect to be dark because it was outside of the passband. I would agree with the suggestion that the harmonics are at a low level relative to the main signal because they are masked by band noise when you open the filter up. I don't think there is much risk of calling someone on the third harmonic by mistake. I don't know what the voltage level of the line output is but the traces disappear if you turn the level down to 2, which unfortunately is too low for most sound card programs. I don't know if those same harmonics are present on the speaker or headphone outputs, as distinct from the computer audio feed. I can only say that I find the K3 audio exceptionally pleasant to listen to. I much prefer it to the K2, or the FT-817, which are the only other radios I have. The only other radio I have had that sounded as clean and low-distortion as the K3 was an IC-756PRO that I had many years ago. If the harmonics are down by the kind of amounts that others have measured then the distortion figure is still within the specification for what after all is not meant to be an audiophile quality hi-fi output stage. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 ___ 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 Harmonic Distortion
Yes indeed it would be a sorry situation if an operator can't tell the difference between a desired signal and an audio harmonic, fortunately my thread is not about that. Anyway, the noise/distortion is still there coming out of the headphone socket. Berni Joe Subich, W4TV wrote: Jim, Insignificant depends on the decoder, what you are decoding (PSK or RTTY), band conditions, and the operator. If a PSK operator is using the IF with a broadband setting and tries to work a signal that's really a harmonic, it won't work -- he'll be transmitting on a frequency displaced from the signal he thinks he's working (displaced by 2X the audio frequency of the actual signal if it's a third harmonic, 1X if it't the second harmonic). If it's a crowded RTTY contest, there can be lots of big signals creating that IM. Or the operator could be using a narrow roofing filter and those other signals are not there or heavily suppressed, so can't cause IM. It would be a sorry situation if an operator can't tell the difference between a desired signal and an audio harmonic down 50 dB. K3_Line_out.jpg shows the line out spectrum of my K3 at 1 KHz, Data_A, 2.8 KHz 1st IF filter and 4 KHz filter. The third harmonic is -62 dB and the fifth harmonic is - 80 dB. See: www.microHAM-USA.com/Downloads/K3_Line_Out.jpg. A typical waterfall does not show the spurious signals at the soundcard input (noise on the cables) which is well below the band noise - typically around -60 dBu. 73, ... Joe, W4TV -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Brown Sent: Monday, September 01, 2008 1:33 PM To: elecraft@mailman.qth.net Subject: RE: [Elecraft] K3 Harmonic Distortion On Mon, 1 Sep 2008 12:38:31 -0400, Joe Subich, W4TV wrote: Jim is entirely correct although we will disagree a bit about the need to keep the line out as low as he suggests. My own measurements say the harmonic distortion is insignificant as long as the Line Out levels stay below .5V RMS. Insignificant depends on the decoder, what you are decoding (PSK or RTTY), band conditions, and the operator. If a PSK operator is using the IF with a broadband setting and tries to work a signal that's really a harmonic, it won't work -- he'll be transmitting on a frequency displaced from the signal he thinks he's working (displaced by 2X the audio frequency of the actual signal if it's a third harmonic, 1X if it't the second harmonic). If it's a crowded RTTY contest, there can be lots of big signals creating that IM. Or the operator could be using a narrow roofing filter and those other signals are not there or heavily suppressed, so can't cause IM. The headphone outputs are exceptionally clean as long as the audio amplifier level is kept below 2V peak (1.4V RMS) and the output impedance is not too low. In fact, noise in the audio amplifier (headphones) is 70 dB below the desired (CW at 500 Hz) signal +/- 250 Hz and 80 dB below the desired signal above that. All harmonics are down more than 60 dB as long as the headphone level is not at levels that could damage hearing ( 1.4V RMS). YES! My measurements of the headphone output, taken at about 1 volt RMS, show harmonic distortion at about 0.02% and IM at less than 0.1%. That is VERY VERY good! 1VRMS is LOUD! The headphone output in the K3 is cleaner than any amateur receiver I have seen and certainly better than the current crop from Ikensu or Yaecomwood. Yes. 73, Jim ___ 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 -- ___ 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 Harmonic Distortion
Julian, G4ILO wrote: I think it was me who used the term ghost signals when referring to the harmonically related CW traces I could see on the CW Skimmer display. Julian, About 6 months ago I found a similar situation with another radio and another program. In that case the distortion was definitely caused by the sound card input being overdriven, not by the radio. I am not saying that that is happening for you, only that it CAN happen with certain equipment. Here are the details if you want to know. I was building a new interface that lets me operate PSK-31 and other modes (including pactor 2) with switching between any of two radios and any two hardware modems and soundcard. It is also designed to work with both my desktop computer and my laptop (HP ZT-3000) by manually moving the cable. Serial port was switched along with the modems. The radios were FT-1000D and TS-570, both interfaced through the connector on the back. The 1000D (now sold to finance K3) has a single fixed output level, the 570 three selectable levels. I selected the level most closely matching the 1000D. The software was MixW running on the HP laptop. I found that I could not only see a give station in two places, but copy their PSK-31 in both places! The second frequency was outside (above) the filter cutoff, but the signal was about as strong as the one in the passband. I don't remember the actual frequencies, but there was a big difference in them, such as double or triple. I didn't determine if the ghost was created as a harmonic or by mixing, but it was good copy and strong. (Hmmm,... wonder if PSK would be copiable on a harmonic?) My interface has a volume control for the output (as well as input) of each radio. When I turned down the output at the interface (not touching the radio), the ghost went away. On a tangent topic: I had previously run the 570 with the laptop using a much simpler interface, and somewhat marginal results (did not run into any ghost, was probably using a lower output level selected on the radio). That interface had short audio cables. The new interface has long cables for flexibility in placing the equipment around the shack. When I first tried to transmit, there was a horrible hum on the signal. I had tied together the 3 grounds of the 570 at the aux connector. I solved the problem completely by running separate 3 grounds from the 570 to the interface box with its transformers. The 1000D had no such need, maybe because its PSU was built-in) but I implemented both radio cables with separate grounds to be prepared for future radios. I should be covered for the K3, whether it behaves like a 1000D or like a 570. I wonder though if the K3 is more similar to one or the other in its grounding scheme... 73, Erik K7TV KX-1 T-1 K3 on order -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p832903.html Sent from the Elecraft mailing list archive at Nabble.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 Harmonic Distortion
On Mon, 01 Sep 2008 18:45:36 -0400, Jack Smith wrote: I've found that the LIN OUT port has typical third harmonic levels around -45 dB from the fundamental, with the LIN OUT level set at 10, the factory default. The headphone port, under the same conditions, will show the third harmonic down about 70 dB or so at levels appropriate for my Sony high sensitivity headphones. Cranking the audio level up will cause higher distortion on the headphone port, but only at levels that are impossible to listen to as they are so loud as to be unbearable. I've also seen some non-harmonic artifacts, particularly when very strong signals are pumped into the K3's antenna port. Jack, I assembled the first of the following reports in June after getting my first K3 running, and sent privately to the guys at Elecraft. That's why the new default LIN OUT gain is 10 rather than 50. It's also why there's a note in the new manual about LIN OUT level. http://audiosystemsgroup.com/K3FilterStudy.pdf A month or two later, I prepared a report on filters in my Yaesu FT1000MPs (mostly Inrads) and my K3. http://audiosystemsgroup.com/FilterTestNotes.pdf This second report describes the test methodology use for the earlier work, which uses rather a high quality pro audio FFT system (EASERA SysTun). My measurements compare pretty well with yours, but use a very different measurement method that is not dependent on the distortion of a signal generator. My method also makes the IM stick out like a sore thumb! As you can see from the first graph in the first pdf, distortion at the headphone output (the black curve) is 0.02% 2nd harmonic, 0.014% 3rd harmonic, and IM on the order of 0.1%. This was done at about 1 VRMS, and was done after the LIN OUT measurements without changing levels. The only difference between Joe's measurements and mine is that my analyzer has a bit more resolution, but we're all getting the same result. The headphone out is VERY VERY VERY good, but the LiN Out starts producing distortion at a rather low level. BUT, that low level is quite sufficient to drive a sound card. As to the setting of 3 or 10. The distortion is mainly caused by the output transformer, and distortion in an output transformer increases rapidly at low frequencies when it approaches its amplitude limit. The data output is MOSTLY intended for decoding digital signals, especially RTTY, and the distortion at 2 kHz is a LOT less than at 400 Hz for the same levels. But distortion is excited not only from signal, but from noise, and impulse noise can get pretty high. Taking all of this into account, I run my LIN OUT gain at 3, and recommend that setting. 73, Jim K9YC ___ 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 Harmonic Distortion
Anyway, the noise/distortion is still there coming out of the headphone socket. The spectrum display you sent me shows an excessive level of 50 Hz harmonics - some 15 dB above the noise floor and only 40 dB below the desired signal from 150 Hz to above 3 KHz. That strongly indicates serious grounding issues, power supply filtering problems, improper power supply decoupling and/or soundcard instability. I suggest you read K9YC's information on interfacing and RFI www.audiosystemsgroup.com/publish.htm and resolve that noise issue first. I have seen the K3 audio output go spurious when presented a bad load or encountering regeneration (feedback from powered speakers) due to bad grounds. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Berni G0IDA Sent: Monday, September 01, 2008 7:13 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 Harmonic Distortion Yes indeed it would be a sorry situation if an operator can't tell the difference between a desired signal and an audio harmonic, fortunately my thread is not about that. Anyway, the noise/distortion is still there coming out of the headphone socket. Berni Joe Subich, W4TV wrote: Jim, Insignificant depends on the decoder, what you are decoding (PSK or RTTY), band conditions, and the operator. If a PSK operator is using the IF with a broadband setting and tries to work a signal that's really a harmonic, it won't work -- he'll be transmitting on a frequency displaced from the signal he thinks he's working (displaced by 2X the audio frequency of the actual signal if it's a third harmonic, 1X if it't the second harmonic). If it's a crowded RTTY contest, there can be lots of big signals creating that IM. Or the operator could be using a narrow roofing filter and those other signals are not there or heavily suppressed, so can't cause IM. It would be a sorry situation if an operator can't tell the difference between a desired signal and an audio harmonic down 50 dB. K3_Line_out.jpg shows the line out spectrum of my K3 at 1 KHz, Data_A, 2.8 KHz 1st IF filter and 4 KHz filter. The third harmonic is -62 dB and the fifth harmonic is - 80 dB. See: www.microHAM-USA.com/Downloads/K3_Line_Out.jpg. A typical waterfall does not show the spurious signals at the soundcard input (noise on the cables) which is well below the band noise - typically around -60 dBu. 73, ... Joe, W4TV ___ 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
