KAT3 antenna tuner
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I've recently installed the KAT3 in my K3. The instructions are quite
vague and I'm not sure mine is operating correctly. First, the manual says there are 30 memories/band for the ATU settings. These seem to change automatically as I tune around. The question is, does the unit switch settings at the points at which I tuned or half way between? IOW, if I tuned at 1820 and 1860, and tune up from the bottom of the band, the tuner should start with the 1820 settings. Ideally, when I get to 1840 it should switch to the 1860 settings. Is this what happens? When I go to the LC set menu, I see the value of C and L. The manual says I can change C by turning the VFO A knob. When I do, the relays click but the display doesn't change. If I turn the VFO B knob to change L nothing happens. After turning VFO B, VFO A stops working! If I then tap ATU TUNE, it goes to another part of the menu entirely! I started on this topic because the tuner failed to find a good match at 1800. My VNA shows the impedance at the TX connector as 22+j8 which should be well within the proper range. 73, Roger -- Remember the USS Liberty (AGTR-5) http://ussliberty.org/ ______________________________________________________________ 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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After another interesting round of CQ 160 I would like to beat
the K3 drum a little also, I found myself feeling guilty many times, I had the width set down under 400HZ and tuning the band would work DX and not even realize there was a 10 over 9 station less than a half KC up or down from me. Had no problem with klix etc with most stations. Had one /KH6 out here that would be at times 10 KHZ wide with strange buzz on his signal, raspy and wide. Be interested to know what type or radio that was. Can say bar none that the K3 performs better than any radio I have owned or used under these type of conditions. I have my pet peeves about a few items but they are over ridden at present by its performance in crowded conditions. Worked about 5 new ones even so was a nice contest for me. One question I have, when the band is wall to wall with strong signals the CW note seems to have a raspy quality on receive, not a real pure DC note, is this some side effect of DSP or what? Maybe its just my ears. Tuned 20 meters this morning and all sounds fine, its just when there are many many strong signals on the band, I hear this, have heard it before but figured it is my ears. This is slight and most may not even hear it. No blanker on, no NR on, just standard settings. 73 Merv KH7C ______________________________________________________________ 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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Merv,
I noticed some of the "raspy" or "buzzy" quality you heard, but for me it was not on all signals. I have also noted that quality on signals for the past week or so; perhaps it is atmospheric. For the first time, I turned on the K3's ATT and found that I was even better able to separate callers, particularly when trying to pick out relatively weaker EU signals from stronger NA signals responding to my CQ. This, of course, was all going on in the midst of many strong signals spaced very close together. Brian K1LI On Sun, Jan 31, 2010 at 1:53 PM, Merv Schweigert <[hidden email]> wrote: > > One question I have, when the band is wall to wall with strong signals > the CW note seems to have a raspy quality on receive, not a real > pure DC note, is this some side effect of DSP or what? Maybe its > just my ears. Tuned 20 meters this morning and all sounds fine, > its just when there are many many strong signals on the band, I hear > this, have heard it before but figured it is my ears. This is > slight and most may not even hear it. > No blanker on, no NR on, just standard settings. > 73 Merv KH7C 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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In reply to this post by Merv Schweigert
Merv, I agree with all that except feeling guilty. I think some of the raspyness comes from a very loud signal with the audio gain set too high. I notice it in contests when the heat is on, but not so much otherwise. I turn the gain up to pick out a weak one then don't turn it back down until the raspy distortion gets to me. I enjoyed my K3 more this time than before because of the "NOISE" thread that went on and on to the distress of some. This thread helped me to understand the fine points of the AGC and NB much better and increased the considerable ability of the K3 by using these features better than before.
It was a great contest with great propagation in spite of some local noise (that the NB handled superbly) and S8 to S9 atomospheric noise for a lot of the time. Great contest, great transceiver, but how did we miss each other Merv? You are a frequent contest contact, but not this time! Willis 'Cookie' Cooke K5EWJ ________________________________ From: Merv Schweigert <[hidden email]> Cc: [hidden email] Sent: Sun, January 31, 2010 12:53:22 PM Subject: [Elecraft] Beat the drum a little After another interesting round of CQ 160 I would like to beat the K3 drum a little also, I found myself feeling guilty many times, I had the width set down under 400HZ and tuning the band would work DX and not even realize there was a 10 over 9 station less than a half KC up or down from me. Had no problem with klix etc with most stations. Had one /KH6 out here that would be at times 10 KHZ wide with strange buzz on his signal, raspy and wide. Be interested to know what type or radio that was. Can say bar none that the K3 performs better than any radio I have owned or used under these type of conditions. I have my pet peeves about a few items but they are over ridden at present by its performance in crowded conditions. Worked about 5 new ones even so was a nice contest for me. One question I have, when the band is wall to wall with strong signals the CW note seems to have a raspy quality on receive, not a real pure DC note, is this some side effect of DSP or what? Maybe its just my ears. Tuned 20 meters this morning and all sounds fine, its just when there are many many strong signals on the band, I hear this, have heard it before but figured it is my ears. This is slight and most may not even hear it. No blanker on, no NR on, just standard settings. 73 Merv KH7C ______________________________________________________________ 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 |
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In reply to this post by Merv Schweigert
> One question I have, when the band is wall to wall with strong signals > the CW note seems to have a raspy quality on receive, Please see the firmware release notes for MCU 3.03/DSP 2.10 from 17 March 2009. Especially the topic "New AGC features especially for use in pileups" 73, Lyle KK7P PS- Firmware release notes are available for viewing in K3 Utility Help. LJ ______________________________________________________________ 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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In reply to this post by Roger D Johnson
On Jan 31, 2010, at 1/31 10:34 AM, Roger D Johnson wrote: > I started on this topic because the tuner failed to find a good > match at > 1800. To see the approximate range of the internal K3 antenna tuner at 1800 kc, take a look here http://homepage.mac.com/chen/Technical/Tuner/tuner1.8.pdf (warning, it is a very large 9 MB PDF file (lots of points), if you download as PDF and view with a PDF reader, you can rescale, etc faster than viewing from a web browser). Each dot indicates the impedance at the antenna port when the radio port of the tuner is set to 50 ohms. So the tuner should tune an antenna that is the conjugate of where a dot lands on the Smith Chart. The green points are for the case trx > series L : shunt C > antenna, and the blue points are when the tuner switches to trx > shunt C > series L > antenna. > My VNA shows the impedance at the TX connector as 22+j8 which should > be well within the proper range. The conjugate of 22 + j8 ohms appears as 0.44 - j0.16 ohm on the normalized Smith Chart in the PDF file. That is just barely inside the coverage region of the tuner. You might try manually setting the tuner to the trx > shunt C > series L > antenna position, turn C to the max (1200+600+300+...) and then manually adjusting around the small values of L for lowest SWR. From my fiddling with the values, a 50 ohm source appears to prefer large shunt C followed by a small series L on the way to a 22 + j8 ohms antenna . It could be possible that other circuitry is preventing you from reaching precisely that area of the tuner. One thing you can do is to move the impedance of what you see at the end of your current transmission line. Since you have a VNA, you might want to play with changing the line length of the 50 ohm transmission line (or use a short length of a different impedance line to transform the impedance that you are currently seeing) so that its conjugate is more inside the dotted region of the PDF file. Also, since you have a VNA, why not temporarily disconnect the transceiver output from the tuner, replace it with a 50 ohm resistor and look at antenna port of the tuner with the VNA? You can then see the conjugate of the impedances which your tuner can transform into 50 ohms. 73 Chen, W7AY P.S. Anyone who wants to run this program for other frequencies just send me a note and I can either send you the app or the Xcode project. You need to be running at least Mac OS X 10.5 (also works fine on 10.6). If you want to modify it for the KAT100 L and C values, you will need to change the component tables in the source, and recompile under the Xcode IDE. Some caveats: the chart shows the combinations of C and L values without taking into consideration any strays. It also does not take into consideration the effects of the KBPF3. ______________________________________________________________ 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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In reply to this post by K1LI
On Sun, 31 Jan 2010 14:23:33 -0500, Brian Machesney wrote:
>For the first time, I turned on the K3's ATT and found that I was even >better able to separate callers, particularly when trying to pick out >relatively weaker EU signals from stronger NA signals responding to my CQ. Those of us with lots of grey hair learned 50 years ago that the most important control on our receiver was the RF Gain. They didn't come with attenuators or preamps in those days, but we also learned to switch them to a shorter antenna when they got overloaded. With a modern radio, on bands below 20M, the ATTenuator should almost always be ON and the PREamp should almost always be OFF for the greatest ability to separate weak signals from strong ones. On 20M you can usually turn off the ATTenuator, but you may not need the preamp until you go to higher bands. Another hint -- to pull really weak ones out from between strong signals, turn down the RF gain to the point where you are just hearing the weak one. During the 160M contest this weekend, preamp was off, ATT was on, and my RF gains were at about 2'o'clock. 73, Jim K9YC ______________________________________________________________ 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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In reply to this post by Kok Chen
>From what I calculate, 22 +j8 ought to be relatively easy to match, if the KAT3 schematic is correct. A low-pass L with series L = 1.48 uH, C = 1967 pF gets it to 1.009:1, assuming no strays and Qc = 1000, Ql = 200.
If my paper and pencil addition is correct, the available C ~ 2600 pF allows a match to a load of ~16 +j20. (with L ~ 0) Since I prefer matching at the antenna, I don't have a KAT3, so this is all a paper guess. Wes N7WS --- On Sun, 1/31/10, Kok Chen <[hidden email]> wrote: > From: Kok Chen <[hidden email]> > Subject: Re: [Elecraft] KAT3 antenna tuner > To: "Elecraft Reflector" <[hidden email]> > Date: Sunday, January 31, 2010, 1:27 PM > > On Jan 31, 2010, at 1/31 10:34 AM, Roger D > Johnson wrote: > > > I started on this topic because the tuner failed to > find a good > > match at > > 1800. > > To see the approximate range of the internal K3 antenna > tuner at 1800 > kc, take a look here > > http://homepage.mac.com/chen/Technical/Tuner/tuner1.8.pdf > > (warning, it is a very large 9 MB PDF file (lots of > points), if you > download as PDF and view with a PDF reader, you can > rescale, etc > faster than viewing from a web browser). > > Each dot indicates the impedance at the antenna port when > the radio > port of the tuner is set to 50 ohms. So the tuner > should tune an > antenna that is the conjugate of where a dot lands on the > Smith Chart. > > The green points are for the case trx > series L : shunt > C > antenna, > and the blue points are when the tuner switches to trx > > shunt C > > series L > antenna. > > > My VNA shows the impedance at the TX connector as > 22+j8 which should > > be well within the proper range. > > > The conjugate of 22 + j8 ohms appears as 0.44 - j0.16 ohm > on the > normalized Smith Chart in the PDF file. That is just > barely inside > the coverage region of the tuner. > > You might try manually setting the tuner to the trx > > shunt C > series > L > antenna position, turn C to the max > (1200+600+300+...) and then > manually adjusting around the small values of L for lowest > SWR. > > From my fiddling with the values, a 50 ohm source appears > to prefer > large shunt C followed by a small series L on the way to a > 22 + j8 > ohms antenna . It could be possible that other > circuitry is > preventing you from reaching precisely that area of the > tuner. > > One thing you can do is to move the impedance of what you > see at the > end of your current transmission line. Since you have > a VNA, you > might want to play with changing the line length of the 50 > ohm > transmission line (or use a short length of a different > impedance line > to transform the impedance that you are currently seeing) > so that its > conjugate is more inside the dotted region of the PDF > file. > > Also, since you have a VNA, why not temporarily disconnect > the > transceiver output from the tuner, replace it with a 50 ohm > resistor > and look at antenna port of the tuner with the VNA? > You can then see > the conjugate of the impedances which your tuner can > transform into 50 > ohms. > > 73 > Chen, W7AY > > P.S. Anyone who wants to run this program for other > frequencies just > send me a note and I can either send you the app or the > Xcode project. > You need to be running at least Mac OS X 10.5 (also works > fine on > 10.6). If you want to modify it for the KAT100 L and > C values, you > will need to change the component tables in the source, and > recompile > under the Xcode IDE. > > Some caveats: the chart shows the combinations of C and L > values > without taking into consideration any strays. It also > does not take > into consideration the effects of the KBPF3. ______________________________________________________________ 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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In reply to this post by Jim Brown-10
I am 61 years old and more than 40 as a ham and always since I started on hamradio with the tube type receivers has used the volumen control almost to the maximun and then control the signal with the RF gain control,no matter which radio you will be using,this is the best way to cut down band noise and close freq QRM,,without a doubt the K3 is the highest performer in the market and doing this it will work even better,I have never used my preamp,not even on 10M,the K3 has enough sensitivity not to use it,on 40 and 80M I always have my ATT engaged and I am able to pull any weak dx station no matter how weak it is and even with a strong one at 2Khz away my freq.
My two cents. AD4C "For a refined ham it is compulsory to own a k3" --- On Sun, 1/31/10, Jim Brown <[hidden email]> wrote: From: Jim Brown <[hidden email]> Subject: [Elecraft] Attenuator and RF Gain Settings To: "[hidden email]" <[hidden email]> Date: Sunday, January 31, 2010, 10:09 PM On Sun, 31 Jan 2010 14:23:33 -0500, Brian Machesney wrote: >For the first time, I turned on the K3's ATT and found that I was even >better able to separate callers, particularly when trying to pick out >relatively weaker EU signals from stronger NA signals responding to my CQ. Those of us with lots of grey hair learned 50 years ago that the most important control on our receiver was the RF Gain. They didn't come with attenuators or preamps in those days, but we also learned to switch them to a shorter antenna when they got overloaded. With a modern radio, on bands below 20M, the ATTenuator should almost always be ON and the PREamp should almost always be OFF for the greatest ability to separate weak signals from strong ones. On 20M you can usually turn off the ATTenuator, but you may not need the preamp until you go to higher bands. Another hint -- to pull really weak ones out from between strong signals, turn down the RF gain to the point where you are just hearing the weak one. During the 160M contest this weekend, preamp was off, ATT was on, and my RF gains were at about 2'o'clock. 73, Jim K9YC ______________________________________________________________ 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： Attenuator and RF Gain Settings
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Hello Hector,
I concur your view. I always lower the RF gain to a point equal to the band noise in the s meter. I find many operators just let the RF gain always fully clockwise. Of course, 6m will need a bit more sensitivity. 73 Johnny VR2XMC ----- 郵件原件 ---- 寄件人﹕ Hector Padron <[hidden email]> 收件人﹕ Jim Brown <[hidden email]> 副本(CC) [hidden email] 傳送日期﹕ 2010/2/1 (一) 10:09:07 PM 主題： Re: [Elecraft] Attenuator and RF Gain Settings I am 61 years old and more than 40 as a ham and always since I started on hamradio with the tube type receivers has used the volumen control almost to the maximun and then control the signal with the RF gain control,no matter which radio you will be using,this is the best way to cut down band noise and close freq QRM,,without a doubt the K3 is the highest performer in the market and doing this it will work even better,I have never used my preamp,not even on 10M,the K3 has enough sensitivity not to use it,on 40 and 80M I always have my ATT engaged and I am able to pull any weak dx station no matter how weak it is and even with a strong one at 2Khz away my freq. My two cents. AD4C "For a refined ham it is compulsory to own a k3" --- On Sun, 1/31/10, Jim Brown <[hidden email]> wrote: From: Jim Brown <[hidden email]> Subject: [Elecraft] Attenuator and RF Gain Settings To: "[hidden email]" <[hidden email]> Date: Sunday, January 31, 2010, 10:09 PM On Sun, 31 Jan 2010 14:23:33 -0500, Brian Machesney wrote: >For the first time, I turned on the K3's ATT and found that I was even >better able to separate callers, particularly when trying to pick out >relatively weaker EU signals from stronger NA signals responding to my CQ. Those of us with lots of grey hair learned 50 years ago that the most important control on our receiver was the RF Gain. They didn't come with attenuators or preamps in those days, but we also learned to switch them to a shorter antenna when they got overloaded. With a modern radio, on bands below 20M, the ATTenuator should almost always be ON and the PREamp should almost always be OFF for the greatest ability to separate weak signals from strong ones. On 20M you can usually turn off the ATTenuator, but you may not need the preamp until you go to higher bands. Another hint -- to pull really weak ones out from between strong signals, turn down the RF gain to the point where you are just hearing the weak one. During the 160M contest this weekend, preamp was off, ATT was on, and my RF gains were at about 2'o'clock. 73, Jim K9YC ______________________________________________________________ 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 Yahoo!香港提供網上安全攻略，教你如何防範黑客! 請前往 http://hk.promo.yahoo.com/security/ 了解更多! ______________________________________________________________ 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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Thanks Johny,that's the best way to operate any radio,unfortunately it has a small negative part and is that the S meter will move up been out of calibration when you turn the RF gain counterclockwise but that's not a big deal after all.Only radio I remember will read always the same S level no matter where you set the RF gain is the TT Orion that I owned for a year.
So we all are waiting still for the P4 right ? AD4C "For a refined ham it is compulsory to own a k3" --- On Mon, 2/1/10, Johnny Siu <[hidden email]> wrote: From: Johnny Siu <[hidden email]> Subject: Re： [Elecraft] Attenuator and RF Gain Settings To: "Hector Padron" <[hidden email]>, "Jim Brown" <[hidden email]> Cc: [hidden email] Date: Monday, February 1, 2010, 2:56 PM Hello Hector, I concur your view. I always lower the RF gain to a point equal to the band noise in the s meter. I find many operators just let the RF gain always fully clockwise. Of course, 6m will need a bit more sensitivity. 73 Johnny VR2XMC ----- 郵件原件 ---- 寄件人﹕ Hector Padron <[hidden email]> 收件人﹕ Jim Brown <[hidden email]> 副本(CC) [hidden email] 傳送日期﹕ 2010/2/1 (一) 10:09:07 PM 主題： Re: [Elecraft] Attenuator and RF Gain Settings I am 61 years old and more than 40 as a ham and always since I started on hamradio with the tube type receivers has used the volumen control almost to the maximun and then control the signal with the RF gain control,no matter which radio you will be using,this is the best way to cut down band noise and close freq QRM,,without a doubt the K3 is the highest performer in the market and doing this it will work even better,I have never used my preamp,not even on 10M,the K3 has enough sensitivity not to use it,on 40 and 80M I always have my ATT engaged and I am able to pull any weak dx station no matter how weak it is and even with a strong one at 2Khz away my freq. My two cents. AD4C "For a refined ham it is compulsory to own a k3" --- On Sun, 1/31/10, Jim Brown <[hidden email]> wrote: From: Jim Brown <[hidden email]> Subject: [Elecraft] Attenuator and RF Gain Settings To: "[hidden email]" <[hidden email]> Date: Sunday, January 31, 2010, 10:09 PM On Sun, 31 Jan 2010 14:23:33 -0500, Brian Machesney wrote: >For the first time, I turned on the K3's ATT and found that I was even >better able to separate callers, particularly when trying to pick out >relatively weaker EU signals from stronger NA signals responding to my CQ. Those of us with lots of grey hair learned 50 years ago that the most important control on our receiver was the RF Gain. They didn't come with attenuators or preamps in those days, but we also learned to switch them to a shorter antenna when they got overloaded. With a modern radio, on bands below 20M, the ATTenuator should almost always be ON and the PREamp should almost always be OFF for the greatest ability to separate weak signals from strong ones. On 20M you can usually turn off the ATTenuator, but you may not need the preamp until you go to higher bands. Another hint -- to pull really weak ones out from between strong signals, turn down the RF gain to the point where you are just hearing the weak one. During the 160M contest this weekend, preamp was off, ATT was on, and my RF gains were at about 2'o'clock. 73, Jim K9YC ______________________________________________________________ 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 Yahoo!香港提供網上安全攻略，教你如何防範黑客! 請前往 http://hk.promo.yahoo.com/security/ 了解更多! ______________________________________________________________ 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: Attenuator and RF Gain Settings
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In reply to this post by Jim Brown-10
My experience jibes well with Jim's. Gain throttling is imperative to get more than mediocre results using the K3: http://n1eu.com/K3/K3_agcgain.htm
73, Barry N1EU
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Re: Attenuator and RF Gain Settings
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Re: Attenuator and RF Gain Settings
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Lance,
CW or SSB? Similar conditions do not exist here on SSB. I can't say anything about CW performance right now. Right now, I am listening to a net on 80 meter SSB with both strong and weak signals in the mix. The Preamp is off and ATT is on - and the RF Gain is backed off to about 2 o'clock. The RF Gain position was determined by listening with no signals and reduced until the atmospheric noise was not bothersome. All signals are quite clear, including the weak ones. My AGC settings are THR = 008 and I have moved the SLP up to 004 for listening to a net - I normally run it at 002 which makes a greater difference in audio volume between strong and weak signals. With those settings at this particular time, it is almost (but not quite) like having squelch on when there is no signal present. 73, Don W3FPR Lance Wilson wrote: > This is a very interesting thread. I am seeing a similar RF gain/AGC issue on > my K3 (I posted a description of this effect on 1/31). While I have also > defaulted to presetting the AFG and use the RF gain to control receiver > performance, I have noticed issues with the AGC on the K3 that make it > behave differently than other radios that I have tried. The K3 has both > hardware and DSP/firmware AGC. > > Strong signals (over S9) cause the AGC to behave normally but weak signals > (DSP/firmware) behave oddly with an apparent, and I say apparent, noise > issue. Audio quality of weak signals with the AGC on also seems to be > slightly compromised as compared to operation with the AGC off. > > Perhaps weak signal performance of the K3 with AGC on needs some > DSP/firmware modification. In the meantime, I am using the rig in a similar > fashion as Barry and other have described. > > Lance, NR7N > > 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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In reply to this post by Lance Wilson
Lance and All,
I don't think this is so much an "issue" (as in rig specific) as it is a fact of life. In other words, this technique works with just about any receiver. While each rig I own has somewhat different characteristics, they all benefit from not over-relying on AGC and RF gain. A long time ago I sort of stumbled onto the fact that running the RF gain relatively low was a good thing. I've been more reticent to disengage my AGC because I use headphones a lot, and there always seems to be someone out there who will suddenly pop up on a frequency running mucho power! However, I did go through the process as described by Barry, N1EU, and it does work extremely well. Furthermore, I tried it on a couple of other rigs, and got the same beneficial result. It was an improvement over my more simplistic process of just running both gain controls at minimum, or at least running the RF gain at minimum. I rarely use the pre-amp, and now I'm experimenting with the attenuator. Obviously I've been underutilizing this tool. Anyway, I'm enjoying the comments in this thread, and hopefully learning something! Dave W7AQK ----- Original Message ----- From: "Lance Wilson" <[hidden email]> To: <[hidden email]> Sent: Tuesday, February 02, 2010 7:42 AM Subject: Re: [Elecraft] Attenuator and RF Gain Settings > > This is a very interesting thread. I am seeing a similar RF gain/AGC issue > on > my K3 (I posted a description of this effect on 1/31). While I have also > defaulted to presetting the AFG and use the RF gain to control receiver > performance, I have noticed issues with the AGC on the K3 that make it > behave differently than other radios that I have tried. The K3 has both > hardware and DSP/firmware AGC. > > Strong signals (over S9) cause the AGC to behave normally but weak signals > (DSP/firmware) behave oddly with an apparent, and I say apparent, noise > issue. Audio quality of weak signals with the AGC on also seems to be > slightly compromised as compared to operation with the AGC off. > > Perhaps weak signal performance of the K3 with AGC on needs some > DSP/firmware modification. In the meantime, I am using the rig in a > similar > fashion as Barry and other have described. > > Lance, NR7N > -- > View this message in context: > http://n2.nabble.com/KAT3-antenna-tuner-tp4490403p4501164.html > Sent from the [K3] mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[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: Attenuator and RF Gain Settings
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This post was updated on .
In reply to this post by Don Wilhelm-4
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Re: Attenuator and RF Gain Settings
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Lance,
Both the AF Gain setting and the AGC on/off condition will modify the S-meter response. As a result, comparing S-meter readings with AGC on vs. off is not a valid comparison. All I can say is that "yes" the S-meter reading will change. Some combination of that behavior is present on each receiver I have ever owned or operated. Each one is different. How the S-meter changes with each condition depends on where the particular receiver picks off the S-meter signal. 73, Don W3FPR Lance Wilson wrote: > Don, > > Given how you have set up your K3 I am in agreement with the performance > you've noted. I'm experimenting on 20M, RF gain full on, preamp and att off. > I am also listening under SSB conditions. I have the RF gain fully on only > to experiment with the AGC. > > Here is an example, with the AGC off my noise level on the S-meter is S2 to > S3. With the AGC on it is S6 to S7 with no signal present. If I listen to a > S8 signal with the AGC on my noise level is still S6. With AGC off that same > signal is S7 with a noise level again of S2 to S3. This is not normal AGC > behavior and perhaps there are some issues between the DSP and hardware AGC. > Changing AGC parameters has no effect on what I am seeing. > > Lance, NR7N > > 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: Attenuator and RF Gain Settings
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This post was updated on .
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In reply to this post by Don Wilhelm-4
Since Barry posted his settings some time ago,I have been using them every day on SSB or CW,always with the ATT ON and the preamp OFF and the RFG set around 12 o'clock and I can tell that the weak stations sounds crystal clear as the strong ones,I can't hear any bad audio os minimun distorsion at all,I normally has the 2.8 Khz roofer and the SHIFT set at 1.2 and flat audio at the RX EQ.My band noise under these settings is very low always.
AD4C "For a refined ham it is compulsory to own a k3" --- On Tue, 2/2/10, Don Wilhelm <[hidden email]> wrote: From: Don Wilhelm <[hidden email]> Subject: Re: [Elecraft] Attenuator and RF Gain Settings To: "Lance Wilson" <[hidden email]> Cc: [hidden email] Date: Tuesday, February 2, 2010, 3:10 PM Lance, CW or SSB? Similar conditions do not exist here on SSB. I can't say anything about CW performance right now. Right now, I am listening to a net on 80 meter SSB with both strong and weak signals in the mix. The Preamp is off and ATT is on - and the RF Gain is backed off to about 2 o'clock. The RF Gain position was determined by listening with no signals and reduced until the atmospheric noise was not bothersome. All signals are quite clear, including the weak ones. My AGC settings are THR = 008 and I have moved the SLP up to 004 for listening to a net - I normally run it at 002 which makes a greater difference in audio volume between strong and weak signals. With those settings at this particular time, it is almost (but not quite) like having squelch on when there is no signal present. 73, Don W3FPR Lance Wilson wrote: > This is a very interesting thread. I am seeing a similar RF gain/AGC issue on > my K3 (I posted a description of this effect on 1/31). While I have also > defaulted to presetting the AFG and use the RF gain to control receiver > performance, I have noticed issues with the AGC on the K3 that make it > behave differently than other radios that I have tried. The K3 has both > hardware and DSP/firmware AGC. > > Strong signals (over S9) cause the AGC to behave normally but weak signals > (DSP/firmware) behave oddly with an apparent, and I say apparent, noise > issue. Audio quality of weak signals with the AGC on also seems to be > slightly compromised as compared to operation with the AGC off. > > Perhaps weak signal performance of the K3 with AGC on needs some > DSP/firmware modification. In the meantime, I am using the rig in a similar > fashion as Barry and other have described. > > Lance, NR7N > > 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 |
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