Re: [Elecraft] K3-P3 SSB spectrum
He said my signal was very clean and asked me to crank up my Mic gain to the max which I reluctantly did for a short transmission. He said it stayed clean with no splatter. Can that be? The K3 ALC is *very* effective. It does not rely on over driving the final amplifier to produce a feedback voltage to reduce gain; instead it keeps the drive from the DSP modulation process to the level needed for the selected power output based on the results of the TXG (transmit gain) calibration. That means the K3 does not overdrive the transmit IF stages, the low power (driver) amplifier or the KPA3 no matter how high you turn the mic gain or the compression level. Yes, the excess compression/mic gain can cause distortion in the DSP modulator but *will not* generate excess bandwidth. Further, since the DSP generated transmit signal goes through the 2.7 or 2.8 KHz filter before passing through the transmit IF, any spatter if further reduced and - more importantly - no more is generated in the rest of the transmit chain because it is run strictly below clipping level at all stages (unless there is a *device failure* in the LPA or KPA3). Every other transceiver (except, perhaps the Flex 6000 series and ANAN) uses a closed loop ALC which is susceptible to distortion from both overshoot and misalignment of individual stage gains. In the days of tube type transmitters this was not the issue it is now since tubes had a relatively soft clipping point - the transition from gain compression to hard clipping occurred over a large change in input levels - such that ALC feedback (typically grid current in the final amplifiers) started well before the tubes saturated. However, with most transistors and FETs the change in input drive necessary to move from the 1 dB compression point to saturation is very small (as little as 1 dB or 20% increase in drive) and that can occur in any of several places (IF, driver, final). As soon as any single stage is driven even close to saturation the signal goes to crap - one need only look at some of the big signals on the band with a good SDR or the P3 to see many that look like AM signals with no carrier due to the amount of IMD that appears in the other sideband. I thought any radio would splatter if over-driven. To review ... the K3's ALC circuits assure that none of the post filter stages are ever over-driven. While the in-band audio can become badly distorted through a combination of excess drive to the DSP (high mic gain) and excess clipping/compression, once the DSP and IF filter have set the transmit bandwidth, the ALC *prevents* overdrive and assures that the frequency conversion and amplification processes do not allow the signal to become excessively wide. 73, ... Joe, W4TV On 2015-06-08 1:56 PM, Richard Fjeld wrote: Just a comment somewhat related to this thread. Not long ago, a ham with an SDR set-up was comparing signals in a round-table for proper bandwidth. He said my signal was very clean and asked me to crank up my Mic gain to the max which I reluctantly did for a short transmission. He said it stayed clean with no splatter. Can that be? I thought any radio would splatter if over-driven. For me, seeing is believing.Dick, n0ce Date: Sun, 7 Jun 2015 16:58:26 -0400 From: li...@subich.com To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3-P3 SSB spectrum The TX Monitor is a time domain display - not a frequency domain display. If you want to see the frequency domain display of your own signal, temporarily disconnect the RS-232 cable between the two (or connect another SDR to a directional coupler in the antenna line). 73, ... Joe, W4TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
Just a comment somewhat related to this thread. Not long ago, a ham with an SDR set-up was comparing signals in a round-table for proper bandwidth. He said my signal was very clean and asked me to crank up my Mic gain to the max which I reluctantly did for a short transmission. He said it stayed clean with no splatter. Can that be? I thought any radio would splatter if over-driven. For me, seeing is believing.Dick, n0ce Date: Sun, 7 Jun 2015 16:58:26 -0400 From: li...@subich.com To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3-P3 SSB spectrum The TX Monitor is a time domain display - not a frequency domain display. If you want to see the frequency domain display of your own signal, temporarily disconnect the RS-232 cable between the two (or connect another SDR to a directional coupler in the antenna line). 73, ... Joe, W4TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
Exactly what I intended to say! And Joe did it without waving his arms. :-) Thanks. 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On 6/8/2015 11:44 AM, Joe Subich, W4TV wrote: He said my signal was very clean and asked me to crank up my Mic gain to the max which I reluctantly did for a short transmission. He said it stayed clean with no splatter. Can that be? The K3 ALC is *very* effective. It does not rely on over driving the final amplifier to produce a feedback voltage to reduce gain; instead it keeps the drive from the DSP modulation process to the level needed for the selected power output based on the results of the TXG (transmit gain) calibration. That means the K3 does not overdrive the transmit IF stages, the low power (driver) amplifier or the KPA3 no matter how high you turn the mic gain or the compression level. Yes, the excess compression/mic gain can cause distortion in the DSP modulator but *will not* generate excess bandwidth. Further, since the DSP generated transmit signal goes through the 2.7 or 2.8 KHz filter before passing through the transmit IF, any spatter if further reduced and - more importantly - no more is generated in the rest of the transmit chain because it is run strictly below clipping level at all stages (unless there is a *device failure* in the LPA or KPA3). Every other transceiver (except, perhaps the Flex 6000 series and ANAN) uses a closed loop ALC which is susceptible to distortion from both overshoot and misalignment of individual stage gains. In the days of tube type transmitters this was not the issue it is now since tubes had a relatively soft clipping point - the transition from gain compression to hard clipping occurred over a large change in input levels - such that ALC feedback (typically grid current in the final amplifiers) started well before the tubes saturated. However, with most transistors and FETs the change in input drive necessary to move from the 1 dB compression point to saturation is very small (as little as 1 dB or 20% increase in drive) and that can occur in any of several places (IF, driver, final). As soon as any single stage is driven even close to saturation the signal goes to crap - one need only look at some of the big signals on the band with a good SDR or the P3 to see many that look like AM signals with no carrier due to the amount of IMD that appears in the other sideband. I thought any radio would splatter if over-driven. To review ... the K3's ALC circuits assure that none of the post filter stages are ever over-driven. While the in-band audio can become badly distorted through a combination of excess drive to the DSP (high mic gain) and excess clipping/compression, once the DSP and IF filter have set the transmit bandwidth, the ALC *prevents* overdrive and assures that the frequency conversion and amplification processes do not allow the signal to become excessively wide. 73, ... Joe, W4TV On 2015-06-08 1:56 PM, Richard Fjeld wrote: Just a comment somewhat related to this thread. Not long ago, a ham with an SDR set-up was comparing signals in a round-table for proper bandwidth. He said my signal was very clean and asked me to crank up my Mic gain to the max which I reluctantly did for a short transmission. He said it stayed clean with no splatter. Can that be? I thought any radio would splatter if over-driven. For me, seeing is believing.Dick, n0ce Date: Sun, 7 Jun 2015 16:58:26 -0400 From: li...@subich.com To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3-P3 SSB spectrum The TX Monitor is a time domain display - not a frequency domain display. If you want to see the frequency domain display of your own signal, temporarily disconnect the RS-232 cable between the two (or connect another SDR to a directional coupler in the antenna line). 73, ... Joe, W4TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to k6...@foothill.net - No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.5961 / Virus Database: 4355/9975 - Release Date: 06/08/15 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
Perhaps it would be good for understanding to know that the audio processing algorithms in a K3 are entirely digital. Any analog audio input to the K3 is immediately converted to a number soup, and at that point any analog mental pictures of what happens no longer apply. ALC, as understood from older analog circuits, is really not a good description. Clipping is not a good description. Our mental expectation from those processes include the effects of diodes that run those processes as implemented in older analog circuit rigs. Even compression, as we are used to hearing it, does not apply. You simply are not driving diodes anywhere in the audio process. Wayne has devised proprietary algorithms for processing the number soup that is your digitized audio. It is our unconscious analog evaluation of four bars solid and the fifth flickering that makes that smell like overdriving and distortion to us. In the number soup plus algorithm world, that is no big deal. In this day and age there are many solid and verified digital processes in use that simply have no analog circuit equivalent at all. The only reason we have volume controls is the need for analog-minded operators (that is not a dun, just a reality) to be able to intuitively operate the rig. The four double knobs on the front left of the rig each control a potentiometer which has a standard voltage across it. The wipe of the pot goes to a very minimalist analog-digital converter which then sends a number across a multiplexed digital bus to the CPU. The pot+A/D converter sends NUMERICAL ADVICE to the CPU. Contrary to an analog circuit understanding, there is never an audio voltage across the pot. There will never be scratchy audio due to incomplete contact by the pot wiper arm. The four knobs to the right of the concentrics are all encoders. The advice to the CPU from them is I have just been advanced one blip clockwise, or one blip counterclockwise. Every effect from those is entirely programmatic in the firmware. The K3 is made to seem like an analog radio to allow intuitive operation, but it is the firmware that sets the essential behavior of the radio. Analog considerations apply to things like amplifiers in the transmit/amplifier chain, or in physical characteristics of synthesizers, etc, for things like distortion, noise, state changes, etc. Brave new world, digital. When I can't stand it any more, I go turn on my Collins 75A3, Johnson Ranger and Courier, breathe a sign of relief and do things the old way for a while. There everything is simple, all tubes, electronic parts you can see without magnification, what I learned from my Elmers, and doesn't require any non-intuitive thinking to understand. If I don't want to deal with throwing all the RX/TX switches, I turn on the Yaesu FT101ZD, which is a treasured gift from PEARL back in my New York days. But it's mostly transistors, so not strictly legit. I put up with all this digital nonsense in a K3 because I like hearing 20 dB farther down into the soup than with my 75A3. I like being able to have my voice processed into something that carries in all the cr*p on the SSB frequencies. I like the visual graphical display of all the frequencies. I like the digital settings that cancel out key clicks. I like the filter response skirts that go all the way down to somewhere below the water table. I really like my K3 for all kinds of reasons. And the ghost of my WCTT Chief Engineer elmer, who spent his time building exact copies of Gates AM BC 833 tube transmitters, holed up in the transmitter building down at the swamp in Corbin, Ky where I took my first FCC exam, just gave me a good swift kick in the b*tt, and whispered Traitor in my ear. There wasn't a transistor anywhere in that place at the time, and certainly nothing digital except the power switches :) 73, Y'all Guy K2AV On Mon, Jun 8, 2015 at 1:56 PM, Richard Fjeld rpfj...@outlook.com wrote: Just a comment somewhat related to this thread. Not long ago, a ham with an SDR set-up was comparing signals in a round-table for proper bandwidth. He said my signal was very clean and asked me to crank up my Mic gain to the max which I reluctantly did for a short transmission. He said it stayed clean with no splatter. Can that be? I thought any radio would splatter if over-driven. For me, seeing is believing.Dick, n0ce Date: Sun, 7 Jun 2015 16:58:26 -0400 From: li...@subich.com To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3-P3 SSB spectrum The TX Monitor is a time domain display - not a frequency domain display. If you want to see the frequency domain display of your own signal, temporarily disconnect the RS-232 cable between the two (or connect another SDR to a directional coupler in the antenna line). 73, ... Joe, W4TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http
[Elecraft] K3-P3 SSB spectrum
Don't get to phone very often but most of the museum ships seem to be on SSB today. An awful lot of signals seem to have most of their energy in close to the carrier and sound constricted [a technical term]. There are occasional ones that look pretty even and they sound great. I sure wish there was a way to look at my SSB spectrum on the P3. Anybody know if the new TX monitor capability will do that? 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
Hi Fred, I have one on order based on my understanding that it does. If I'm incorrect I'm sure I'll be corrected. 73 ! Ken - K0PP On Jun 7, 2015 1:33 PM, Fred Jensen k6...@foothill.net wrote: Don't get to phone very often but most of the museum ships seem to be on SSB today. An awful lot of signals seem to have most of their energy in close to the carrier and sound constricted [a technical term]. There are occasional ones that look pretty even and they sound great. I sure wish there was a way to look at my SSB spectrum on the P3. Anybody know if the new TX monitor capability will do that? 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to kengk...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
The TX Monitor is a time domain display - not a frequency domain display. If you want to see the frequency domain display of your own signal, temporarily disconnect the RS-232 cable between the two (or connect another SDR to a directional coupler in the antenna line). 73, ... Joe, W4TV On 2015-06-07 3:32 PM, Fred Jensen wrote: Don't get to phone very often but most of the museum ships seem to be on SSB today. An awful lot of signals seem to have most of their energy in close to the carrier and sound constricted [a technical term]. There are occasional ones that look pretty even and they sound great. I sure wish there was a way to look at my SSB spectrum on the P3. Anybody know if the new TX monitor capability will do that? 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to li...@subich.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
The new P3TXMON does not include transmit spectrum monitoring. Although I’ve never tried it, if you unplug the P3 from the K3, you can/might observe your transmit spectrum. But this isn’t a feature. Alan sent an email about this some time ago .. don’t have it, but you can probably find it in the archive. The K3 does not normally provide a transmit spectrum output. There’s only transmit IF “leakage”, which varies by K3, the time of day, phase of the moon, lottery numbers … so it wouldn’t be consistent enough to have a documented “feature”. Grant NQ5T On Jun 7, 2015, at 2:56 PM, Ken G Kopp kengk...@gmail.com wrote: Hi Fred, I have one on order based on my understanding that it does. If I'm incorrect I'm sure I'll be corrected. 73 ! Ken - K0PP On Jun 7, 2015 1:33 PM, Fred Jensen k6...@foothill.net wrote: Don't get to phone very often but most of the museum ships seem to be on SSB today. An awful lot of signals seem to have most of their energy in close to the carrier and sound constricted [a technical term]. There are occasional ones that look pretty even and they sound great. I sure wish there was a way to look at my SSB spectrum on the P3. Anybody know if the new TX monitor capability will do that? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] K3-P3 SSB spectrum
Thanks to all who replied. I now know that the new feature is time domain only which doesn't help me. I tried unplugging the RS-232 cable, and apparently the phase of the moon is not quite right because I really don't see much. I tried running up the gain [SCALE] to no avail, brought the noise up too. I think I'll have a QSO with a local with a P3 and he can do a screen capture and send it to me. Thanks again, 73, Fred K6DGW - Northern California Contest Club - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 - www.cqp.org On 6/7/2015 2:04 PM, GRANT YOUNGMAN wrote: The new P3TXMON does not include transmit spectrum monitoring. Although I’ve never tried it, if you unplug the P3 from the K3, you can/might observe your transmit spectrum. But this isn’t a feature. Alan sent an email about this some time ago .. don’t have it, but you can probably find it in the archive. The K3 does not normally provide a transmit spectrum output. There’s only transmit IF “leakage”, which varies by K3, the time of day, phase of the moon, lottery numbers … so it wouldn’t be consistent enough to have a documented “feature”. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
