Re: : K3 receiver noise questionable test results
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Re: : K3 receiver noise questionable test results
 
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Kudos to Al for supplying these settings that make my K3 #3192 sound almost
identical to my TS570D (albeit, into different speakers, but lets not open up THAT can of worms)! -Lu-W4LT- From: "Al Lorona" <[hidden email]> Cc: <[hidden email]> Sent: Saturday, December 19, 2009 3:40 AM Subject: Re: [Elecraft] K3 receiver noise questionable test results > But a few of the K3 owners that have pro-audio > instrumentation have reported that the K3 audio > response is more like 'white noise' (a flat response), >as opposed to other receivers which have a 'pink > noise' audio spectrum. If that's the case, then the K3's receiver equalizer can be set up to mimic a pink rolloff which is -3 dB per octave. 50 Hz : + 9 dB 100 : + 6 200 : + 3 400 : 0 800 : - 3 1600 : - 6 3200 : - 9 No virus found in this outgoing message Checked by PC Tools AntiVirus (6.1.0.25 - 6.13950). http://www.pctools.com/free-antivirus/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise questionable test results
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> If that's the case, then the K3's receiver equalizer can be set up > to mimic a pink rolloff which is -3 dB per octave. > > 50 Hz : + 9 dB > 100 : + 6 > 200 : + 3 > 400 : 0 > 800 : - 3 > 1600 : - 6 > 3200 : - 9 If one is going to attempt to mimic the "pink noise" behavior, there is no need to bother with the low frequency boost. It simply puts more strain on the audio amplifier, increasing the amount of IMD products, with little or no aural benefit. A better RX EQ configuration with essentially the same perceived sound: 50: -16 dB (reduce sub-vocal noise and hum) 100: 0 dB 200: 0 dB 400: 0 dB 800: 0 dB 1600: -3 dB 2400: -5 dB 3200: -6 dB Note: the K3 RX EQ would be more useful (and more intuitive to adjust) if the 8 bands had a constant Q response and were based on 2/3 octave frequencies - specifically: 1 100 Hz 2 160 Hz 3 250 Hz 4 400 Hz 5 630 Hz 6 1000 Hz 7 1600 Hz 8 2500 Hz Additional controls at 63 and 4000 Hz would be worthwhile if a 10 band configuration were possible. However, since audio below 100 Hz and above 3000 Hz is generally not used for communications purposes and the K3 DSP response is limited to 4200 Hz, making bands 1 and 8 "shelving" instead of peaking responses would be a usable alternative to the additional bands. 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Luis V. Romero > Sent: Saturday, December 19, 2009 12:50 PM > To: [hidden email] > Subject: Re: [Elecraft] : K3 receiver noise questionable test results > > > Kudos to Al for supplying these settings that make my K3 > #3192 sound almost identical to my TS570D (albeit, into > different speakers, but lets not open up THAT can of worms)! > > -Lu-W4LT- > > From: "Al Lorona" <[hidden email]> > Cc: <[hidden email]> > Sent: Saturday, December 19, 2009 3:40 AM > Subject: Re: [Elecraft] K3 receiver noise questionable test results > > > > But a few of the K3 owners that have pro-audio > instrumentation have > >reported that the K3 audio response is more like 'white > noise' (a flat > >response), as opposed to other receivers which have a 'pink > > noise' audio spectrum. > > If that's the case, then the K3's receiver equalizer can be set up > to mimic a pink rolloff which is -3 dB per octave. > > 50 Hz : + 9 dB > 100 : + 6 > 200 : + 3 > 400 : 0 > 800 : - 3 > 1600 : - 6 > 3200 : - 9 > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise questionable test results
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I agree the 50Hz boost adds nothing useful, but I find to increase the 100, 200 and 400 values make the audio sound more balanced and easier on the ears. This is not boosting the bass so much as trying to compensate for the bass roll-off inherent in the K3. I will agree that low frequencies have no benefit when trying to copy weak signals but surely it is the role of the filtering to cut out those frequencies by manual adjustment when trying to receive a weak signal? The purpose of equalization is to achieve a pleasant and balanced audio response for general use.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: : K3 receiver noise questionable test results
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Is this for voice or cw reception? The consonant sounds in voice, are
mainly contained in the 1600 to 3200 Hz range; rolling this range off is likely to reduce voice readability. Are there or will there be mode dependent settings for the receive equalizer? I've tried using an external high/low/bandpass filter with the K3 on cw and it's not beneficial for me but then my hearing is damaged with midrange loss and distortion in one ear as a result of having meniere's disease. 73, Dunc, W5DC Julian, G4ILO wrote: > > Joe Subich, W4TV-4 wrote: > >> >> If one is going to attempt to mimic the "pink noise" behavior, >> there is no need to bother with the low frequency boost. It >> simply puts more strain on the audio amplifier, increasing the >> amount of IMD products, with little or no aural benefit. A >> better RX EQ configuration with essentially the same perceived >> sound: >> >> 50: -16 dB (reduce sub-vocal noise and hum) >> 100: 0 dB >> 200: 0 dB >> 400: 0 dB >> 800: 0 dB >> 1600: -3 dB >> 2400: -5 dB >> 3200: -6 dB >> >> >> > > I agree the 50Hz boost adds nothing useful, but I find to increase the 100, > 200 and 400 values make the audio sound more balanced and easier on the > ears. This is not boosting the bass so much as trying to compensate for the > bass roll-off inherent in the K3. > > I will agree that low frequencies have no benefit when trying to copy weak > signals but surely it is the role of the filtering to cut out those > frequencies by manual adjustment when trying to receive a weak signal? The > purpose of equalization is to achieve a pleasant and balanced audio response > for general use. > > ----- > Julian, G4ILO. K2 #392 K3 #222. > * G4ILO's Shack - http://www.g4ilo.com > * KComm - http://www.g4ilo.com/kcomm.html > * KTune - http://www.g4ilo.com/ktune.html > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise questionable test results
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In reply to this post by Julian, G4ILO
> I agree the 50Hz boost adds nothing useful, but I find to > increase the 100, 200 and 400 values make the audio sound > more balanced and easier on the ears. This is not boosting > the bass so much as trying to compensate for the bass > roll-off inherent in the K3. My tests with an audio spectrum analyzer using both broadband noise and internally generated receiver noise show that the K3 is flat from 100 Hz to 4100 Hz when using the 6 or 13 KHz roofing filters with FC=2.10 and BW=4.00 to either speakers or Line Out. Headphone response is another issue that can be addressed with the Rev C/Rev D DSP assemblies or replacing the 10 uF headphone coupling capacitors with 100 uF caps and/or using high impedance headphones. I find that boosting the bass results in a muddy and distorted sound when using quality external speakers. The bass boost makes the amplifier work too hard to overcome the issues at the output and 9 dB of gain at 100 Hz is effectively pushing the 100 mW headphone amplifier to over 750 mW - well beyond its capabilities. If you absolutely must have more "low end" the way to accomplish that is by further cutting the high end. 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Julian, G4ILO > Sent: Saturday, December 19, 2009 3:02 PM > To: [hidden email] > Subject: Re: [Elecraft] : K3 receiver noise questionable test results > > > > > > Joe Subich, W4TV-4 wrote: > > > > > > > > If one is going to attempt to mimic the "pink noise" behavior, > > there is no need to bother with the low frequency boost. It > > simply puts more strain on the audio amplifier, increasing the > > amount of IMD products, with little or no aural benefit. A > > better RX EQ configuration with essentially the same perceived > > sound: > > > > 50: -16 dB (reduce sub-vocal noise and hum) > > 100: 0 dB > > 200: 0 dB > > 400: 0 dB > > 800: 0 dB > > 1600: -3 dB > > 2400: -5 dB > > 3200: -6 dB > > > > > > I agree the 50Hz boost adds nothing useful, but I find to > increase the 100, 200 and 400 values make the audio sound > more balanced and easier on the ears. This is not boosting > the bass so much as trying to compensate for the bass > roll-off inherent in the K3. > > I will agree that low frequencies have no benefit when trying > to copy weak signals but surely it is the role of the > filtering to cut out those frequencies by manual adjustment > when trying to receive a weak signal? The purpose of > equalization is to achieve a pleasant and balanced audio > response for general use. > > ----- > Julian, G4ILO. K2 #392 K3 #222. > * G4ILO's Shack - http://www.g4ilo.com > * KComm - http://www.g4ilo.com/kcomm.html > * KTune - http://www.g4ilo.com/ktune.html > > -- > View this message in context: > http://n2.nabble.com/Re-K3-receiver-noise-questionable-test-re Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise - my test results (long)
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In reply to this post by Joe Subich, W4TV-4
Joe,
I think you may have hit on some major part of the "problem" here. I measured the passband (and out of passband) response of my K3 and my K2, Yaesu FT-900 and Yaesu FT-817. All measurements were with the SSB filter in all transceivers, and the K3 DSP width was set to maximum. My K2 has the 2.4 kHz filter and the Yaesu transceivers have the stock SSB filter. The test setup consisted of an Elecraft broadband noise generator feeding that receiver and the output was observed with Spectrogram. The receiver gain controls were adjusted to place the peak in-passband response at -30 dB. I also connected an antenna and listened to several signals participating in a 40 meter roundtable, and made my own 'quality of sound' assessment. Several things became apparent as a result of these tests. 1) the K3 in-passband response is almost flat - from 500 Hz to 2500 Hz it showed less than 1 dB variation. 2) All the other passband responses were down about 5 dB at 500 Hz and essentially flat from 1 kHz to 1600 Hz, then began a gradual falloff, being down 3 dB at 2 kHz, down 8 dB at 2.5 kHz, the Yaesus were down 17 dB while the K2 was down 36 dB (this is the effective high end of the passband). So within the passband, there is a rolloff similar to that which you suggested for the receive EQ settings on all but the K3. 3) The response outside the passband on the low end was also interesting. The K3 at 200 Hz was only down 3 dB, but dropped steeply at lower frequencies (I do not have the low frequency mod on my K3). The K2 was down 26 dB at 200 Hz while the Yaesus were down 20 dB. 4) On he high frequency side out of the passband, the K2 and K3 had almost no audio response that showed on Spectrogram - in other words greater than 60 dB down from the passband peak. The Yaesu FT-900 had audio artifacts that were only 44 dB down at 4 kHz and for the FT-817 were only 35 dB down. At 5 kHz the FT-900 had audio content at -50 dB and the FT-817 had content only 40 dB down. Summary of my observations - the in-passband response of both Yaesu filters and the K2 filter tapered off above 1800 Hz, similar to a "pink noise" response, while the K3 response was remarkably flat with very steep filter skirts. The skirt slope of the other filter passbands were more gentle. On the high frequency end, both Yaesu transceivers had considerable audio content while the K2 and K3 content was much lower. My conclusions: I am not certain what K3 owners are perceiving as noise any more than I had been before these tests. The flatter passband of the K3 may be sub-consciously perceived as being more 'harsh', but I could not equate that to 'noise'. The other filters with a high end in-passband response that drops off similar to a "pink noise" response *could* be causing a perception of additional noise *if* their local noise has significant content in the 2 kHz to 3 kHz range - yes, the K3 will make this section of the audio spectrum louder than the other receiver I measured. The "audio hiss" is not coming from the high frequency spectrum outside the passband because in that area, the K3 and the K2 are much more quiet than the others measured. It would be interesting (at least to me) for someone to make similar measurements on an FT-1000 - perhaps with the INRAD filter. I am especially interested to know if the in-passband response shows a similar taper at 2 kHz and above, and what is the response for the FT-1000 above the filter passband. For those trying the "pink noise rolloff", my measurements suggest that you should set the RX EQ bands from 100 Hz through 1600 Hz at 0 dB, 2400 at -3 dB, and 3200 at -5 dB. The 50 Hz band can be set at -16 dB for the reasons Joe has stated. 73, Don W3FPR Joe Subich, W4TV wrote: > If one is going to attempt to mimic the "pink noise" behavior, > there is no need to bother with the low frequency boost. It > simply puts more strain on the audio amplifier, increasing the > amount of IMD products, with little or no aural benefit. A > better RX EQ configuration with essentially the same perceived > sound: > > 50: -16 dB (reduce sub-vocal noise and hum) > 100: 0 dB > 200: 0 dB > 400: 0 dB > 800: 0 dB > 1600: -3 dB > 2400: -5 dB > 3200: -6 dB > > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise questionable test results
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In reply to this post by Dunc Carter - W5DC
We're talking about SSB here but I also like the same kind of sound when receiving CW with the filter wide open. The idea is not to make the audio sound muffled and lose intelligibility. Personally I think the bass boost is more important to improving the sound than the treble cut. But a lot depends on what you are listening on. The K3 internal speaker has a lot more bass than headphones or many external speakers. I can't fault the audio on the internal speaker or on computer headphones plugged in round the back, using the settings given below, but two pairs of hi-fi stereo headphones and some external passive speakers (all of which probably 8 ohm impedance) are lacking in bass and tiring to listen to. The settings I'm currently using are: 50Hz +0 100Hz +3 200Hz +6 400Hz +6 800Hz +3 1600Hz +0 2400Hz -3 3200Hz -9 I do hope there will be mode dependent settings eventually because FM, in particular, doesn't need equalization like this.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: : K3 receiver noise questionable test results
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In reply to this post by Joe Subich, W4TV-4
I agree the line output is pretty flat which is why the MP3 files I tried to make didn't demonstrate the problem. I think that rather than replace the DSP board I'll look for some high impedance headphones. But even with them, I still feel the sound on SSB needs some bass/mid range boost and a bit of extreme treble cut. I doubt if the headphones need anywhere near 100mW of output to drive them so overloading the amplifier should not be a problem.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: : K3 receiver noise - my test results (long)
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In reply to this post by Don Wilhelm-4
I used Spectran rather than Spectrogram which has the advantage that it can also be used interactively as an audio filter. I found that decreasing the bass content by increasing the frequency of the high pass filter made the audio seem more noisy. I presume this is because high frequency noise components then comprised a greater proportion of the signal and were emphasized. I think that if people were using low impedance headphones and the original DSP board with small value coupling capacitors then they would find the audio over-bright and harsh, as I did. I tried different AGC settings and agree that lower AGC THR settings make the radio sound more noisy, so that may also be a factor. I am now using AGC THR = 8 which is the maximum and might well use a higher setting if it was available. I am also using AGC SLP = 1. Having identified the problems and made some adjustments to settings the K3 sounds really good now on high impedance phones and on the internal speaker.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: : K3 receiver noise - my test results (long)
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In reply to this post by Don Wilhelm-4
> It would be interesting (at least to me) for someone to make similar > measurements on an FT-1000 - perhaps with the INRAD filter. I am > especially interested to know if the in-passband response shows a > similar taper at 2 kHz and above, and what is the response for the > FT-1000 above the filter passband. Here are some measurements using Spectrogram and broadband noise: FT-2000 --- MK V --- IC-706 ------ K3 ------ Analog DSP MKIIG Norm BW=4 EQ 50 -34 -44 -49 -46 -35 -7 -35 100 -31 -24 -27 -40 -18 -6 -18 200 -17 -10 -9 -21 -5 -2 -5 300 -6 -4 -4 -11 -1 0 -1 400 -3 -2 -1 -5 0 0 0 600 -2 -1 0 -1 0 0 2 800 -1 -1 0 0 0 0 1 1000 -1 -1 0 -1 0 0 0 1200 0 -1 0 -2 0 0 0 1400 0 0 0 -1 0 0 -2 1600 -1 -2 -1 -2 0 0 -3 1800 -2 -3 -2 -3 0 0 -4 2000 -5 -5 -2 -4 -1 0 -5 2200 -7 -6 -3 -6 -2 0 -7 2400 -8 -8 -4 -8 -2 0 -8 2600 -10 -10 -6 -15 -3 0 -9 2700 -23 -13 -7 -27 -4 0 -10 2800 -34 -19 -11 -31 -8 0 -14 2900 -41 -32 -24 -33 -18 0 -24 3000 -50 -43 -36 -35 -58 0 -60 3100 -42 -67 0 3200 -58 0 3300 0 3400 0 3500 0 3600 -1 3700 -2 3800 -4 3900 -5 4000 -13 4100 -34 4150 -66 All measurements were made at the speaker output for consistency. All measurements were made in USB mode with the default filter settings. FT-1000MP Mark V was measured with both the analog and DSP (100-3100 Hz setting) detectors. The two additional K3 measurements are 1) FM filter, BW=4.00 and FC=2.00 and 2) "NORM" using the "pink EQ" settings (1.60=-3, 2.40=-5, 3.20=-6). Note the K3 audio amplifier is the cleanest hands down. The other transceivers had noise floors at about -120 dBV (IC-706 mkIIg was -100 dBV). Except for what appear to be artifacts of the ADC clock at 4, 8, 12, 16, 18 and 20 KHz the K3 out of band audio noise is <140 dBV. 73, ... Joe, W4TV > -----Original Message----- > From: Don Wilhelm [mailto:[hidden email]] > Sent: Saturday, December 19, 2009 5:14 PM > To: [hidden email] > Cc: [hidden email] > Subject: Re: [Elecraft] : K3 receiver noise - my test results (long) > > > Joe, > > I think you may have hit on some major part of the "problem" here. I > measured the passband (and out of passband) response of my K3 > and my K2, > Yaesu FT-900 and Yaesu FT-817. All measurements were with the SSB > filter in all transceivers, and the K3 DSP width was set to > maximum. My > K2 has the 2.4 kHz filter and the Yaesu transceivers have the > stock SSB > filter. > > The test setup consisted of an Elecraft broadband noise generator > feeding that receiver and the output was observed with > Spectrogram. The > receiver gain controls were adjusted to place the peak in-passband > response at -30 dB. > I also connected an antenna and listened to several signals > participating in a 40 meter roundtable, and made my own 'quality of > sound' assessment. > > Several things became apparent as a result of these tests. > 1) the K3 in-passband response is almost flat - from 500 Hz > to 2500 Hz > it showed less than 1 dB variation. > 2) All the other passband responses were down about 5 dB at > 500 Hz and > essentially flat from 1 kHz to 1600 Hz, then began a gradual falloff, > being down 3 dB at 2 kHz, down 8 dB at 2.5 kHz, the Yaesus > were down 17 > dB while the K2 was down 36 dB (this is the effective high end of the > passband). So within the passband, there is a rolloff > similar to that > which you suggested for the receive EQ settings on all but the K3. > 3) The response outside the passband on the low end was also > interesting. The K3 at 200 Hz was only down 3 dB, but > dropped steeply > at lower frequencies (I do not have the low frequency mod on my K3). > The K2 was down 26 dB at 200 Hz while the Yaesus were down 20 dB. > 4) On he high frequency side out of the passband, the K2 and K3 had > almost no audio response that showed on Spectrogram - in other words > greater than 60 dB down from the passband peak. The Yaesu FT-900 had > audio artifacts that were only 44 dB down at 4 kHz and for the FT-817 > were only 35 dB down. At 5 kHz the FT-900 had audio content > at -50 dB > and the FT-817 had content only 40 dB down. > > Summary of my observations - the in-passband response of both Yaesu > filters and the K2 filter tapered off above 1800 Hz, similar > to a "pink > noise" response, while the K3 response was remarkably flat with very > steep filter skirts. The skirt slope of the other filter > passbands were > more gentle. > > On the high frequency end, both Yaesu transceivers had considerable > audio content while the K2 and K3 content was much lower. > > My conclusions: I am not certain what K3 owners are > perceiving as noise > any more than I had been before these tests. The flatter > passband of > the K3 may be sub-consciously perceived as being more 'harsh', but I > could not equate that to 'noise'. The other filters with a high end > in-passband response that drops off similar to a "pink noise" > response > *could* be causing a perception of additional noise *if* their local > noise has significant content in the 2 kHz to 3 kHz range - > yes, the K3 > will make this section of the audio spectrum louder than the other > receiver I measured. The "audio hiss" is not coming from the high > frequency spectrum outside the passband because in that area, > the K3 and > the K2 are much more quiet than the others measured. > > It would be interesting (at least to me) for someone to make similar > measurements on an FT-1000 - perhaps with the INRAD filter. I am > especially interested to know if the in-passband response shows a > similar taper at 2 kHz and above, and what is the response for the > FT-1000 above the filter passband. > > For those trying the "pink noise rolloff", my measurements > suggest that > you should set the RX EQ bands from 100 Hz through 1600 Hz at > 0 dB, 2400 > at -3 dB, and 3200 at -5 dB. The 50 Hz band can be set at -16 dB for > the reasons Joe has stated. > > 73, > Don W3FPR > > Joe Subich, W4TV wrote: > > If one is going to attempt to mimic the "pink noise" behavior, > > there is no need to bother with the low frequency boost. It > > simply puts more strain on the audio amplifier, increasing the > > amount of IMD products, with little or no aural benefit. A > > better RX EQ configuration with essentially the same perceived > > sound: > > > > 50: -16 dB (reduce sub-vocal noise and hum) > > 100: 0 dB > > 200: 0 dB > > 400: 0 dB > > 800: 0 dB > > 1600: -3 dB > > 2400: -5 dB > > 3200: -6 dB > > > > > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise - my test results (long)
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Joe,
Fine business on those measurements, and thank you for providing the data. I note that all except the K3 show the taper from 1600 Hz to the upper passband edge that follows something similar to a "pink noise" spectrum. The K3 is flat without EQ. It is interesting that the K3 Norm does show some falloff, but not nearly as much as either the FT-2000 or the MK V or IC-706. I am ready to conclude that the K3's ultra-flat in-passband response is the cause of several of the "noisy" responses. That can be easily handled by shaping with the RX EQ if one desires. I do data modes frequently, and prefer the flat response of the K3. The audio response above the filter passband apparently has less influence than I had originally expected. 73, Don W3FPR Joe Subich, W4TV wrote: >> It would be interesting (at least to me) for someone to make similar >> measurements on an FT-1000 - perhaps with the INRAD filter. I am >> especially interested to know if the in-passband response shows a >> similar taper at 2 kHz and above, and what is the response for the >> FT-1000 above the filter passband. >> > > Here are some measurements using Spectrogram and broadband noise: > > FT-2000 --- MK V --- IC-706 ------ K3 ------ > > Analog DSP MKIIG Norm BW=4 EQ > > 50 -34 -44 -49 -46 -35 -7 -35 > 100 -31 -24 -27 -40 -18 -6 -18 > 200 -17 -10 -9 -21 -5 -2 -5 > 300 -6 -4 -4 -11 -1 0 -1 > 400 -3 -2 -1 -5 0 0 0 > 600 -2 -1 0 -1 0 0 2 > 800 -1 -1 0 0 0 0 1 > 1000 -1 -1 0 -1 0 0 0 > 1200 0 -1 0 -2 0 0 0 > 1400 0 0 0 -1 0 0 -2 > 1600 -1 -2 -1 -2 0 0 -3 > 1800 -2 -3 -2 -3 0 0 -4 > 2000 -5 -5 -2 -4 -1 0 -5 > 2200 -7 -6 -3 -6 -2 0 -7 > 2400 -8 -8 -4 -8 -2 0 -8 > 2600 -10 -10 -6 -15 -3 0 -9 > 2700 -23 -13 -7 -27 -4 0 -10 > 2800 -34 -19 -11 -31 -8 0 -14 > 2900 -41 -32 -24 -33 -18 0 -24 > 3000 -50 -43 -36 -35 -58 0 -60 > 3100 -42 -67 0 > 3200 -58 0 > 3300 0 > 3400 0 > 3500 0 > 3600 -1 > 3700 -2 > 3800 -4 > 3900 -5 > 4000 -13 > 4100 -34 > 4150 -66 > > All measurements were made at the speaker output for consistency. > All measurements were made in USB mode with the default filter > settings. FT-1000MP Mark V was measured with both the analog > and DSP (100-3100 Hz setting) detectors. > > The two additional K3 measurements are 1) FM filter, BW=4.00 > and FC=2.00 and 2) "NORM" using the "pink EQ" settings (1.60=-3, > 2.40=-5, 3.20=-6). > > Note the K3 audio amplifier is the cleanest hands down. The other > transceivers had noise floors at about -120 dBV (IC-706 mkIIg was > -100 dBV). Except for what appear to be artifacts of the ADC > clock at 4, 8, 12, 16, 18 and 20 KHz the K3 out of band audio > noise is <140 dBV. > > 73, > > ... Joe, W4TV > > > > > > > > > >> -----Original Message----- >> From: Don Wilhelm [mailto:[hidden email]] >> Sent: Saturday, December 19, 2009 5:14 PM >> To: [hidden email] >> Cc: [hidden email] >> Subject: Re: [Elecraft] : K3 receiver noise - my test results (long) >> >> >> Joe, >> >> I think you may have hit on some major part of the "problem" here. I >> measured the passband (and out of passband) response of my K3 >> and my K2, >> Yaesu FT-900 and Yaesu FT-817. All measurements were with the SSB >> filter in all transceivers, and the K3 DSP width was set to >> maximum. My >> K2 has the 2.4 kHz filter and the Yaesu transceivers have the >> stock SSB >> filter. >> >> The test setup consisted of an Elecraft broadband noise generator >> feeding that receiver and the output was observed with >> Spectrogram. The >> receiver gain controls were adjusted to place the peak in-passband >> response at -30 dB. >> I also connected an antenna and listened to several signals >> participating in a 40 meter roundtable, and made my own 'quality of >> sound' assessment. >> >> Several things became apparent as a result of these tests. >> 1) the K3 in-passband response is almost flat - from 500 Hz >> to 2500 Hz >> it showed less than 1 dB variation. >> 2) All the other passband responses were down about 5 dB at >> 500 Hz and >> essentially flat from 1 kHz to 1600 Hz, then began a gradual falloff, >> being down 3 dB at 2 kHz, down 8 dB at 2.5 kHz, the Yaesus >> were down 17 >> dB while the K2 was down 36 dB (this is the effective high end of the >> passband). So within the passband, there is a rolloff >> similar to that >> which you suggested for the receive EQ settings on all but the K3. >> 3) The response outside the passband on the low end was also >> interesting. The K3 at 200 Hz was only down 3 dB, but >> dropped steeply >> at lower frequencies (I do not have the low frequency mod on my K3). >> The K2 was down 26 dB at 200 Hz while the Yaesus were down 20 dB. >> 4) On he high frequency side out of the passband, the K2 and K3 had >> almost no audio response that showed on Spectrogram - in other words >> greater than 60 dB down from the passband peak. The Yaesu FT-900 had >> audio artifacts that were only 44 dB down at 4 kHz and for the FT-817 >> were only 35 dB down. At 5 kHz the FT-900 had audio content >> at -50 dB >> and the FT-817 had content only 40 dB down. >> >> Summary of my observations - the in-passband response of both Yaesu >> filters and the K2 filter tapered off above 1800 Hz, similar >> to a "pink >> noise" response, while the K3 response was remarkably flat with very >> steep filter skirts. The skirt slope of the other filter >> passbands were >> more gentle. >> >> On the high frequency end, both Yaesu transceivers had considerable >> audio content while the K2 and K3 content was much lower. >> >> My conclusions: I am not certain what K3 owners are >> perceiving as noise >> any more than I had been before these tests. The flatter >> passband of >> the K3 may be sub-consciously perceived as being more 'harsh', but I >> could not equate that to 'noise'. The other filters with a high end >> in-passband response that drops off similar to a "pink noise" >> response >> *could* be causing a perception of additional noise *if* their local >> noise has significant content in the 2 kHz to 3 kHz range - >> yes, the K3 >> will make this section of the audio spectrum louder than the other >> receiver I measured. The "audio hiss" is not coming from the high >> frequency spectrum outside the passband because in that area, >> the K3 and >> the K2 are much more quiet than the others measured. >> >> It would be interesting (at least to me) for someone to make similar >> measurements on an FT-1000 - perhaps with the INRAD filter. I am >> especially interested to know if the in-passband response shows a >> similar taper at 2 kHz and above, and what is the response for the >> FT-1000 above the filter passband. >> >> For those trying the "pink noise rolloff", my measurements >> suggest that >> you should set the RX EQ bands from 100 Hz through 1600 Hz at >> 0 dB, 2400 >> at -3 dB, and 3200 at -5 dB. The 50 Hz band can be set at -16 dB for >> the reasons Joe has stated. >> >> 73, >> Don W3FPR >> >> Joe Subich, W4TV wrote: >> >>> If one is going to attempt to mimic the "pink noise" behavior, >>> there is no need to bother with the low frequency boost. It >>> simply puts more strain on the audio amplifier, increasing the >>> amount of IMD products, with little or no aural benefit. A >>> better RX EQ configuration with essentially the same perceived >>> sound: >>> >>> 50: -16 dB (reduce sub-vocal noise and hum) >>> 100: 0 dB >>> 200: 0 dB >>> 400: 0 dB >>> 800: 0 dB >>> 1600: -3 dB >>> 2400: -5 dB >>> 3200: -6 dB >>> >>> >>> >>> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.717 / Virus Database: 270.14.114/2575 - Release Date: 12/19/09 03:33:00 > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise - my test results (long)
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So do I. RX EQ is now (thanks, Wayne) disabled in data modes, so you can shape the response any way you want for SSB without interfering with digi operation. It needs to be flat for FM, especially if you want to do packet / APRS using the new 2m module, so hopefully per-mode EQ is still on the to-do list somewhere.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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In reply to this post by Don Wilhelm-4
Guys,
Thanks for all the measurements. It is clear that "noisy" is a integrated perception-- kind of like what "good audio" is. It all depends upon your nearly impossible to quantify reference for "good" is. It kind of reminds me of when I switched over from a CRT monitor which had a convex face to one with a flat screen. All of a sudden the "straight" lines displayed as curved. The mind had been correcting for the curvature and was still trying to do so with the flat screen. After a period of use the "curved straight lines" became flat again. "Noisy" is more than likely just different from what one is used to. "Noisy" thus varies lots from individual to individual. On a check ride for an IFR instrument license, the examiner deducted points because I was not using squelch on the radio. All of the years of listening to radios with noise present was what I found "normal". Extracting the signal from the noise was no burden. Besides, in critical stages of flight, I wanted to know if my radio had died. To him, the noise was an terrible distraction. Once this was explained to him, it all made sense. What is a manufacturer of a radio to do? It seems to me that the K3 approach of providing a flat response, which the user can alter with other controls, is the most universal solution. It is not as if these settings have to be changed often. As a narrow filter CW user, all of this disucssion seems totally irrelevant. What sounds noisy here is SSB. 73 de Brian/K3KO Don Wilhelm wrote: > Joe, > > Fine business on those measurements, and thank you for providing the > data. I note that all except the K3 show the taper from 1600 Hz to the > upper passband edge that follows something similar to a "pink noise" > spectrum. The K3 is flat without EQ. It is interesting that the K3 > Norm does show some falloff, but not nearly as much as either the > FT-2000 or the MK V or IC-706. > > I am ready to conclude that the K3's ultra-flat in-passband response is > the cause of several of the "noisy" responses. That can be easily > handled by shaping with the RX EQ if one desires. I do data modes > frequently, and prefer the flat response of the K3. > > The audio response above the filter passband apparently has less > influence than I had originally expected. > > 73, > Don W3FPR > > Joe Subich, W4TV wrote: >>> It would be interesting (at least to me) for someone to make similar >>> measurements on an FT-1000 - perhaps with the INRAD filter. I am >>> especially interested to know if the in-passband response shows a >>> similar taper at 2 kHz and above, and what is the response for the >>> FT-1000 above the filter passband. >>> >> Here are some measurements using Spectrogram and broadband noise: >> >> FT-2000 --- MK V --- IC-706 ------ K3 ------ >> >> Analog DSP MKIIG Norm BW=4 EQ >> >> 50 -34 -44 -49 -46 -35 -7 -35 >> 100 -31 -24 -27 -40 -18 -6 -18 >> 200 -17 -10 -9 -21 -5 -2 -5 >> 300 -6 -4 -4 -11 -1 0 -1 >> 400 -3 -2 -1 -5 0 0 0 >> 600 -2 -1 0 -1 0 0 2 >> 800 -1 -1 0 0 0 0 1 >> 1000 -1 -1 0 -1 0 0 0 >> 1200 0 -1 0 -2 0 0 0 >> 1400 0 0 0 -1 0 0 -2 >> 1600 -1 -2 -1 -2 0 0 -3 >> 1800 -2 -3 -2 -3 0 0 -4 >> 2000 -5 -5 -2 -4 -1 0 -5 >> 2200 -7 -6 -3 -6 -2 0 -7 >> 2400 -8 -8 -4 -8 -2 0 -8 >> 2600 -10 -10 -6 -15 -3 0 -9 >> 2700 -23 -13 -7 -27 -4 0 -10 >> 2800 -34 -19 -11 -31 -8 0 -14 >> 2900 -41 -32 -24 -33 -18 0 -24 >> 3000 -50 -43 -36 -35 -58 0 -60 >> 3100 -42 -67 0 >> 3200 -58 0 >> 3300 0 >> 3400 0 >> 3500 0 >> 3600 -1 >> 3700 -2 >> 3800 -4 >> 3900 -5 >> 4000 -13 >> 4100 -34 >> 4150 -66 >> >> All measurements were made at the speaker output for consistency. >> All measurements were made in USB mode with the default filter >> settings. FT-1000MP Mark V was measured with both the analog >> and DSP (100-3100 Hz setting) detectors. >> >> The two additional K3 measurements are 1) FM filter, BW=4.00 >> and FC=2.00 and 2) "NORM" using the "pink EQ" settings (1.60=-3, >> 2.40=-5, 3.20=-6). >> >> Note the K3 audio amplifier is the cleanest hands down. The other >> transceivers had noise floors at about -120 dBV (IC-706 mkIIg was >> -100 dBV). Except for what appear to be artifacts of the ADC >> clock at 4, 8, 12, 16, 18 and 20 KHz the K3 out of band audio >> noise is <140 dBV. >> >> 73, >> >> ... Joe, W4TV >> >> >> >> >> >> >> >> >> >>> -----Original Message----- >>> From: Don Wilhelm [mailto:[hidden email]] >>> Sent: Saturday, December 19, 2009 5:14 PM >>> To: [hidden email] >>> Cc: [hidden email] >>> Subject: Re: [Elecraft] : K3 receiver noise - my test results (long) >>> >>> >>> Joe, >>> >>> I think you may have hit on some major part of the "problem" here. I >>> measured the passband (and out of passband) response of my K3 >>> and my K2, >>> Yaesu FT-900 and Yaesu FT-817. All measurements were with the SSB >>> filter in all transceivers, and the K3 DSP width was set to >>> maximum. My >>> K2 has the 2.4 kHz filter and the Yaesu transceivers have the >>> stock SSB >>> filter. >>> >>> The test setup consisted of an Elecraft broadband noise generator >>> feeding that receiver and the output was observed with >>> Spectrogram. The >>> receiver gain controls were adjusted to place the peak in-passband >>> response at -30 dB. >>> I also connected an antenna and listened to several signals >>> participating in a 40 meter roundtable, and made my own 'quality of >>> sound' assessment. >>> >>> Several things became apparent as a result of these tests. >>> 1) the K3 in-passband response is almost flat - from 500 Hz >>> to 2500 Hz >>> it showed less than 1 dB variation. >>> 2) All the other passband responses were down about 5 dB at >>> 500 Hz and >>> essentially flat from 1 kHz to 1600 Hz, then began a gradual falloff, >>> being down 3 dB at 2 kHz, down 8 dB at 2.5 kHz, the Yaesus >>> were down 17 >>> dB while the K2 was down 36 dB (this is the effective high end of the >>> passband). So within the passband, there is a rolloff >>> similar to that >>> which you suggested for the receive EQ settings on all but the K3. >>> 3) The response outside the passband on the low end was also >>> interesting. The K3 at 200 Hz was only down 3 dB, but >>> dropped steeply >>> at lower frequencies (I do not have the low frequency mod on my K3). >>> The K2 was down 26 dB at 200 Hz while the Yaesus were down 20 dB. >>> 4) On he high frequency side out of the passband, the K2 and K3 had >>> almost no audio response that showed on Spectrogram - in other words >>> greater than 60 dB down from the passband peak. The Yaesu FT-900 had >>> audio artifacts that were only 44 dB down at 4 kHz and for the FT-817 >>> were only 35 dB down. At 5 kHz the FT-900 had audio content >>> at -50 dB >>> and the FT-817 had content only 40 dB down. >>> >>> Summary of my observations - the in-passband response of both Yaesu >>> filters and the K2 filter tapered off above 1800 Hz, similar >>> to a "pink >>> noise" response, while the K3 response was remarkably flat with very >>> steep filter skirts. The skirt slope of the other filter >>> passbands were >>> more gentle. >>> >>> On the high frequency end, both Yaesu transceivers had considerable >>> audio content while the K2 and K3 content was much lower. >>> >>> My conclusions: I am not certain what K3 owners are >>> perceiving as noise >>> any more than I had been before these tests. The flatter >>> passband of >>> the K3 may be sub-consciously perceived as being more 'harsh', but I >>> could not equate that to 'noise'. The other filters with a high end >>> in-passband response that drops off similar to a "pink noise" >>> response >>> *could* be causing a perception of additional noise *if* their local >>> noise has significant content in the 2 kHz to 3 kHz range - >>> yes, the K3 >>> will make this section of the audio spectrum louder than the other >>> receiver I measured. The "audio hiss" is not coming from the high >>> frequency spectrum outside the passband because in that area, >>> the K3 and >>> the K2 are much more quiet than the others measured. >>> >>> It would be interesting (at least to me) for someone to make similar >>> measurements on an FT-1000 - perhaps with the INRAD filter. I am >>> especially interested to know if the in-passband response shows a >>> similar taper at 2 kHz and above, and what is the response for the >>> FT-1000 above the filter passband. >>> >>> For those trying the "pink noise rolloff", my measurements >>> suggest that >>> you should set the RX EQ bands from 100 Hz through 1600 Hz at >>> 0 dB, 2400 >>> at -3 dB, and 3200 at -5 dB. The 50 Hz band can be set at -16 dB for >>> the reasons Joe has stated. >>> >>> 73, >>> Don W3FPR >>> >>> Joe Subich, W4TV wrote: >>> >>>> If one is going to attempt to mimic the "pink noise" behavior, >>>> there is no need to bother with the low frequency boost. It >>>> simply puts more strain on the audio amplifier, increasing the >>>> amount of IMD products, with little or no aural benefit. A >>>> better RX EQ configuration with essentially the same perceived >>>> sound: >>>> >>>> 50: -16 dB (reduce sub-vocal noise and hum) >>>> 100: 0 dB >>>> 200: 0 dB >>>> 400: 0 dB >>>> 800: 0 dB >>>> 1600: -3 dB >>>> 2400: -5 dB >>>> 3200: -6 dB >>>> >>>> >>>> >>>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> ------------------------------------------------------------------------ >> >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com >> Version: 9.0.717 / Virus Database: 270.14.114/2575 - Release Date: 12/19/09 03:33:00 >> >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: : K3 receiver noise - my test results (long)
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In reply to this post by Don Wilhelm-4
> I note that all except the K3 show the taper from 1600 Hz to > the upper passband edge that follows something similar to a > "pink noise" spectrum. That's fairly clear but since 1600 Hz to the top edge of the passband is less than one octave it is difficult to determine if the roll-off is "pink" (-3dB/octave) or "brown" (-6db/octave). > It is interesting that the K3 Norm does show some falloff, but > not nearly as much as either the FT-2000 or the MK V or IC-706. I should not that the roll-off in the "Norm" setting for this K3 (S/N 622) is due entirely to the roofing filter. If I make the same measurements in LSB, the LF end of the spectrum will be similarly effected and if I run the tests on my other K3 there will be a slight (<1 dB) valley in the midrange. Roofing filters are never absolutely flat but a 1 dB ripple is nothing to be concerned about. Even the "wide" setting has some ripple but not enough to be numerically significant given the resolution of Spectrogram. > I am ready to conclude that the K3's ultra-flat in-passband > response is the cause of several of the "noisy" responses. I don't know if it is the cause of the "noisy" responses but it is probably to blame (along with the headphone response) for the perception that the K3 is "harsh" sounding. Since the human ear is most sensitive in the 2000 - 4000 Hz octave, the flat response of the K3 is perceived as "more noise" by someone using SSB or CW with wide filters. > That can be easily handled by shaping with the RX EQ if one > desires. The most critical RX EQ band is 2400 Hz. Even setting it to -4 or -5 dB without any change at 1600 and 3200 Hz does a lot to "warm up" the audio and make it sound more like other rigs. > I do data modes frequently, and prefer the flat response of > the K3. RX EQ is disabled in DATA mode. If you use DATA A instead of USB you can adjust RX EQ at will for SSB and not effect data mode response. > The audio response above the filter passband apparently has less > influence than I had originally expected. I don't know about that. I can clearly hear several of the ADC clock products even though they are 40 dB or more below audio in the voice passband. They stand out clearly ... as much as 20 dB above the "out of band" noise level. There is also considerable dynamic "program related" noise in the stopband that I'm looking to clean up with the lowpass filter. However, I suspect the audio response is only marginally related to the "noisy receiver" complaints. 73, ... Joe, W4TV > -----Original Message----- > From: Don Wilhelm [mailto:[hidden email]] > Sent: Sunday, December 20, 2009 12:42 AM > To: [hidden email] > Cc: [hidden email] > Subject: Re: [Elecraft] : K3 receiver noise - my test results (long) > > > Joe, > > Fine business on those measurements, and thank you for providing the > data. I note that all except the K3 show the taper from 1600 > Hz to the > upper passband edge that follows something similar to a "pink noise" > spectrum. The K3 is flat without EQ. It is interesting that the K3 > Norm does show some falloff, but not nearly as much as either the > FT-2000 or the MK V or IC-706. > > I am ready to conclude that the K3's ultra-flat in-passband > response is > the cause of several of the "noisy" responses. That can be easily > handled by shaping with the RX EQ if one desires. I do data modes > frequently, and prefer the flat response of the K3. > > The audio response above the filter passband apparently has less > influence than I had originally expected. > > 73, > Don W3FPR > > Joe Subich, W4TV wrote: > >> It would be interesting (at least to me) for someone to > make similar > >> measurements on an FT-1000 - perhaps with the INRAD filter. I am > >> especially interested to know if the in-passband response shows a > >> similar taper at 2 kHz and above, and what is the response for the > >> FT-1000 above the filter passband. > >> > > > > Here are some measurements using Spectrogram and broadband noise: > > > > FT-2000 --- MK V --- IC-706 ------ K3 ------ > > Analog DSP MKIIG Norm BW=4 EQ > > > > 50 -34 -44 -49 -46 -35 -7 -35 > > 100 -31 -24 -27 -40 -18 -6 -18 > > 200 -17 -10 -9 -21 -5 -2 -5 > > 300 -6 -4 -4 -11 -1 0 -1 > > 400 -3 -2 -1 -5 0 0 0 > > 600 -2 -1 0 -1 0 0 2 > > 800 -1 -1 0 0 0 0 1 > > 1000 -1 -1 0 -1 0 0 0 > > 1200 0 -1 0 -2 0 0 0 > > 1400 0 0 0 -1 0 0 -2 > > 1600 -1 -2 -1 -2 0 0 -3 > > 1800 -2 -3 -2 -3 0 0 -4 > > 2000 -5 -5 -2 -4 -1 0 -5 > > 2200 -7 -6 -3 -6 -2 0 -7 > > 2400 -8 -8 -4 -8 -2 0 -8 > > 2600 -10 -10 -6 -15 -3 0 -9 > > 2700 -23 -13 -7 -27 -4 0 -10 > > 2800 -34 -19 -11 -31 -8 0 -14 > > 2900 -41 -32 -24 -33 -18 0 -24 > > 3000 -50 -43 -36 -35 -58 0 -60 > > 3100 -42 -67 0 > > 3200 -58 0 > > 3300 0 > > 3400 0 > > 3500 0 > > 3600 -1 > > 3700 -2 > > 3800 -4 > > 3900 -5 > > 4000 -13 > > 4100 -34 > > 4150 -66 > > > > All measurements were made at the speaker output for consistency. > > All measurements were made in USB mode with the default filter > > settings. FT-1000MP Mark V was measured with both the analog > > and DSP (100-3100 Hz setting) detectors. > > > > The two additional K3 measurements are 1) FM filter, BW=4.00 > > and FC=2.00 and 2) "NORM" using the "pink EQ" settings (1.60=-3, > > 2.40=-5, 3.20=-6). > > > > Note the K3 audio amplifier is the cleanest hands down. The other > > transceivers had noise floors at about -120 dBV (IC-706 mkIIg was > > -100 dBV). Except for what appear to be artifacts of the ADC > > clock at 4, 8, 12, 16, 18 and 20 KHz the K3 out of band audio > > noise is <140 dBV. > > > > 73, > > > > ... Joe, W4TV > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Hi,
Is it just me that have two fairly strong audio spurs at 3.9 and 7.8kHz? By "strong" I mean about 70dB below an AGC saturated CW tone. This is on the line out. The level of these tones are independent on RF gain setting and also independent of the CONFIG:LINE OUT setting. My line out is set at "nor 016" which is low enough that transformer distortion is fairly minimal. I do not hear these tones on the front headphone output which is where I do all my listening, but I have made no attempt to perform any measurements on this output. The tones are definitely from the K3 as they disappear when I turn it off. Look here for a spectral display of my line out with an XG1 generating 50uV: http://ab2tc:82/pictures/k3_line_out_50uv_lev016.png Don't get me wrong. This is fairly clean and I am not of those who perceive the K3 RX audio as "harsh" or "noisy". But I would like the ability set the AGC threshold higher. Even the 008 setting is a little too lively for me on 20m and below (Preamp off of course). BTW 15m is starting to come back to life, but there is disappointingly little ham activity on it. Knut - AB2TC
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Hi again,
Sorry, that link will only work from inside my LAN. Here is a correction: http://ab2tc.getmyip.com:82/pictures/k3_line_out_50uv_lev016.png Knut - AB2TC
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Re: : K3 receiver noise - my test results (long)
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Knut,
No you are not the only one, but there are remedies. See Jack Smith's information at http://www.cliftonlaboratories.com/elecraft_k3_receive_audio.htm. Then install the resistors as indicated in the Elecraft K3 AF Stage Upgrade Instructions. 73, Don W3FPR ab2tc wrote: > Hi again, > > Sorry, that link will only work from inside my LAN. Here is a correction: > > http://ab2tc.getmyip.com:82/pictures/k3_line_out_50uv_lev016.png > > Knut - AB2TC > > > ab2tc wrote: > >> Hi, >> >> Is it just me that have two fairly strong audio spurs at 3.9 and 7.8kHz? >> By "strong" I mean about 70dB <snipP> >> > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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