Noisy K3 receiver
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Wow. Sounds like as much fun as a cell phone. No thanks.
No DSP is ever going to match my preferences AND your preferences AND everyone else's preferences. Heck, we can't even agree on what "proper" AGC is, so Elecraft has given us the controls to set as we see fit. Different strokes for different folks. Always has been, always will be. 73 -- Joe KB8AP On Dec 18, 2009, at 8:43 AM, Wes Stewart wrote: > If the receiver has a properly designed AGC system then there are > only two variables that are potentially the operator's > responsibility: 1) Preamp On/Off and 2) > Attenuator On/Off. With the smarts built into modern radios, why > can't the radio do, for example upon band switching, a little > routine of turning each of these on and off and measuring the > resulting SNR and then setting them accordingly? If an S9+50 dB > neighbor suddenly pops up, the DSP should know sooner than the > operator that the ADC is being overloaded and act accordingly. If > an antenna is changed or a noise source pops up, a simple macro > executed by a key tap could run the routine automatically and be > done with it. > ______________________________________________________________ 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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This is out of hand.
All I have to say is, Folks, THAT'S WHY THERE ARE MENUS!!! Not everyone likes the same thing!! Now tuning on my mail filter to reject anything with "NOISE" or "noisy" in the subject! That's all I can do, No AGC, PRE or ATT on my email. de K2GN/Larry K3 - S/N 3278 ______________________________________________________________ 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 Joe Planisky
To answer the question of whether the K3 is too noisy - does it have
internal noise that limits its performance, I performed a simple test by turning off the agc and comparing the unclipped audio output level with a 50 ohm resistor connected to ANT2 and my multiband vertical dipole on ANT1; on 10 meters, the external noise was 17 dB greater on the vertical dipole with a greater difference on the lower frequency bands. I also checked for the presence of external noise at the mains/line frequency by inspecting the audio output with a spectrum analyzer in AM mode and didn't find any discernible harmonic series of the mains/line frequency plus I didn't find anything for the blanker to blank. The nearest above ground power line is more than a quarter mile away. While this was a rather casually performed test, it seems safe to conclude that my K3 is not noisy. So much for that non-existent problem. 6 meters, on the other hand, is not limited by external noise; perhaps that's why there's a 6 meter preamp option. I haven't adjusted the agc settings; my K3 agc response seems very flat which is what I prefer. As for not using the RF gain, that seems a rather absurd statement unless you don't care about maximizing the receive performance of the K3 under difficult conditions. One recent example that I've commented on previously is being able to blank a strong local's key clicks plus other noises while receiving weak signals with 200 Hz of his operating frequency. The K3 has a flexible set of tools but it's not a magic; if you don't want to make use of all it's capabilities, that's your choice but it's not a choice that I would make. It does seem like we've beaten this topic to death. 73, Dunc, W5DC > > >> If the receiver has a properly designed AGC system then there are >> only two variables that are potentially the operator's >> responsibility: 1) Preamp On/Off and 2) >> Attenuator On/Off. With the smarts built into modern radios, why >> can't the radio do, for example upon band switching, a little >> routine of turning each of these on and off and measuring the >> resulting SNR and then setting them accordingly? If an S9+50 dB >> neighbor suddenly pops up, the DSP should know sooner than the >> operator that the ADC is being overloaded and act accordingly. If >> an antenna is changed or a noise source pops up, a simple macro >> executed by a key tap could run the routine automatically and be >> done with it. >> >> > > ______________________________________________________________ > 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 Larry - K2GN
For what it's worth, as a new K3 owner....I have learned a lot from this
discussion. Jack W4GRJ -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Larry - K2GN Sent: Friday, December 18, 2009 12:36 PM To: Elecraft - K3 Subject: Re: [Elecraft] Noisy K3 receiver This is out of hand. All I have to say is, Folks, THAT'S WHY THERE ARE MENUS!!! Not everyone likes the same thing!! Now tuning on my mail filter to reject anything with "NOISE" or "noisy" in the subject! That's all I can do, No AGC, PRE or ATT on my email. de K2GN/Larry K3 - S/N 3278 ______________________________________________________________ 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: 8.5.427 / Virus Database: 270.14.111/2570 - Release Date: 12/18/09 07:35:00 ______________________________________________________________ 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 |
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In reply to this post by daleputnam
Wow, Dale! You're a swell guy. Hay, I'm building the KPA100 for my K2 and
it's almost finished. I'll let you know how it goes. Gary, N7HTS On Fri, 18 Dec 2009 05:14:38 -0700 Dale Putnam <[hidden email]> wrote: > > Well... if the noisy rx is just way too much to handle... too much to suffer >with... > > I could be convinced to help you out... by paying the shipping to get it >from there to here. > > Just to help you out you see. Look at all the advantages...... > > You would be free to find a lot less noise.... no wait... that would have >happened already... > > I'd have to put up with the noise... > > oh... well... a deal is a deal.... > > my addresss is easy to find, I'll supply it and the box... even pay for >packing... > > just to let you get outta your misery... > > > > Merry Christmas, > > --... ..--- > > Dale - WC7S in Wy > > *G* > > > _________________________________________________________________ > Hotmail: Trusted email with powerful SPAM protection. > http://clk.atdmt.com/GBL/go/177141665/direct/01/ > ______________________________________________________________ > 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 W4GRJ
Let me throw in a penny please.
Just for comparison: FT1kMP : all controls full gain (except AF of course), antenna connected. Then disconnect antenna and listen: nearly no audio, only the receiver noise. K3: do the same. Difference is that when I disconnect the antenna, the noise coming from the speaker is much louder! So the receiver noise is much louder? I thought that that might come from the dsp design. (I think that that is what Don meant) I am open for enlightenment. 73 Arie ______________________________________________________________ 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: Noisy K3 receiver
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In reply to this post by Larry - K2GN
You're right, Larry! Maybe it's time for Lyle to end this thread? I'm sick an tired of all this "noise"!
I had an FT-1000MP (very nice rig) until recently, comparing the two rigs side by side for over a year, with a coax relay for a quick switchover. Then I sold the FT1K and kept the K3. Enough said. 73, Richard
Richard - HB9ANM
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In reply to this post by Bob Naumann W5OV
I would be interested to know how you arrive at that conclusion.
My perception is a LOT of people have posted genuine concerns about noisy K3 receiver. I will add my voice to those that find the K3 noisy receiver very disturbing. I am a casual user I rarely diddle with settings beyond the factory defaults. This is true for the several other late model rigs of different makes I own and operate. I find the K3 very noisy and fatiguing in comparison to any of the other rigs I have when tuning around a relatively quite band. I Rarely use the preamp mostly have the attenuator in. Bryan, Zl1NI > -----Original Message----- > > Stan, > > Those who are complaining are the exceptions to the rule. > > There are thousands of K3 users that are not complaining. There are > a few, > very vocal complainers here. > > 73 ______________________________________________________________ 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 Ralph Parker
I believe there may be a hardware variation component to this. At least,
my main RX and my sub-RX sound like two different radios (S/N #1595). In summary: the main RX sounds near-perfect. On the other hand, the sub-RX has audio hiss above the DSP bandpass at high AF gain settings, and what appear to be digital artifacts within the bandpass that are noticeable at high AF gain settings and narrow bandwidths. In detail: On the main RX, with no antenna, RF gain set to zero and NR, NB and AGC all off, I can turn the AF gain control all the way to the top and still hear nothing - the receiver is completely quiet regardless of the ATT, PRE, filter and mode settings. As I move the RF gain control up, I start hearing receiver noise within the filter bandpass, as expected. With AGC on, I can hear some in-bandpass receiver noise even with the RF gain control at zero, and the within-bandpass noise level is higher than without AGC up to the point where the S-meter goes to zero, after which levels are the same with and without AGC. So far so good, no surprises other than the excellent performance. Now, with all settings in the sub-RX identical to the main RX, I tried the same experiment and got quite different results. With the RF gain at zero, as the AF gain control is increased beyond about 12 o'clock I start hearing high-pitched hiss (outside the filter bandpass). Even with RF gain at around 1 o'clock, with AF gain all the way up the hiss is louder than the in-band noise. With the sub AF gain all the way up and RF gain down, I also hear other noises, a bit like a poorly-controlled audio oscillator with lots of harmonics and other burbling noises; the dominant frequency appears to be the same as the filter Fc. I can hear this in the internal speaker as well as in my headphones. This junk is most evident at narrow bandwidth settings. The junk decreases when the AF gain is backed off, and is drowned out by normal band noise with normal RF gain settings, although I can imagine that it might still contribute to aural fatigue. Again, none of this is audible at all on the main receiver, only the sub-RX. I can only conclude from this, plus the reports on this reflector, that not all K3 receivers are the same. Certainly the two receivers in my K3 sound different. 73, Rich VE3KI ______________________________________________________________ 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 n7ws
You clearly don't understand how AGC and gain distribution in a rig work if you really believe that automatic settings would properly cover everything from ragchewing to contesting to weak signal DXing, all under various types of noise. The strength of the K3 is it's adaptability to almost any signal environment, but yes ... you do need to make the effort to understand how to use it. What you want is an appliance, not a rig. It's not the K3's fault that you gave up on it. Dave AB7E Wes Stewart wrote: > Bill has linked to and quoted Eric's paper (http://wiki.contesting.com/index.php/Setting_receiver_gain_controls) which quite frankly seems way too complicated to me. IMHO, a modern DSP, microprocessor-controlled receiver should figure all of this stuff out automatically and do it for me. > > Make no mistake, as someone licensed for over 50 years and who has designed and built some receivers "back in the day", I've been through all of this "turn off the AGC and back off the RF gain stuff", before. That made sense when the RF gain control was a rheostat in the cathode of the RF stage and actually adjusted RF gain and radios didn't even have product detectors, but I don't think it makes sense today, except possibly is some rare situation. > > If the receiver has a properly designed AGC system then there are only two variables that are potentially the operator's responsibility: 1) Preamp On/Off and 2) > Attenuator On/Off. With the smarts built into modern radios, why can't the radio do, for example upon band switching, a little routine of turning each of these on and off and measuring the resulting SNR and then setting them accordingly? If an S9+50 dB neighbor suddenly pops up, the DSP should know sooner than the operator that the ADC is being overloaded and act accordingly. If an antenna is changed or a noise source pops up, a simple macro executed by a key tap could run the routine automatically and be done with it. > > We have DXpeditions operating on some chunk of coral that are running wireless networks between stations and uploading their logbooks in near real-time to the Internet via satellite yet their operators are still "riding the RF gain control". Something is wrong with this picture. > > Wes N7WS > > --- On Fri, 12/18/09, Bill W4ZV <[hidden email]> wrote: > > > >> Bill W4ZV wrote: >> >>> >>> > > >>> Ralph Parker wrote: >>> >>>> I'm used to leaving the RF gain wide open on the >>>> >> MkV, leaving the audio >> >>>> gain pretty much alone, and maybe switching >>>> >> between SLOW and FAST >> >>>> occasionally. I don't seem to have any trouble >>>> >> hearing the weak ones >> >>>> under >>>> the strong ones. >>>> Now I have to fiddle with the RF gain (a small >>>> >> knob hidden amongst the >> >>>> others) while running a pileup. Not enough hands >>>> >> (or enough brains). >> >>> If you set up your K3 as you described above, I >>> >> guarantee you will have a >> >>> noisy RX. Furthermore, you are wasting the >>> >> dynamic range of the K3 (or >> >>> your MkV for that matter). In a previous post I >>> >> described how to set up >> >>> the K3. Once set up correctly, you should >>> > seldom > >> need to touch either RF >> >>> or AF gain during an entire contest and can simply let >>> >> the K3's excellent >> >>> AGC and dynamic range do the work for you. IMHO >>> >> good ergonomics doesn't >> >>> mean having access to 24 knobs that need to be >>> >> continually adjusted, it >> >>> means not having to adjust them in the first place. >>> >>> 73, Bill W4ZV >>> >>> >> Several have asked for more info about how to set up the K3 >> gain. The >> following is a simplified version of a comprehensive >> article by K3NA below: >> >> http://wiki.contesting.com/index.php/Setting_receiver_gain_controls >> >> Note that Eric's setup is for AGC Off, which is probably >> not a good idea for >> most casual users. I would start with AGC-F using the >> default AGC Menu >> settings. You can >> > check the defaults for each CONFIG: > >> AGC Menu by tapping >> the DISP button while in the appropriate CONFIG Menu (all >> AGC settings begin >> with CONFIG: AGC xxx, and remember that some are only >> accessible with >> CONFIG: TECH MD On). >> >> 1. Have available your desired antenna and a dummy >> load (both on a coax >> switch is ideal) for each band you want to set up (you'll >> at least need to >> do this for major segments like 80/160, 40-18, 15-10 and 6 >> separately (if >> you have the external preamp). >> >> 2. Set AF GAIN back to about 9 o'clock and RF GAIN to >> MAX (fully >> clockwise). This assumes you have the proper AF GAIN >> menu setting for your >> specific headphones (I use AF GAIN - LO for my 32 ohm >> headphones and still >> have tons of audio). >> >> 3. In the following order (first ATT >> > ON, then ATT > >> OFF, then PRE ON) >> alternately switch between your antenna and the dummy >> load. When you hear >> noise increase when switching to the antenna, use the >> lowest gain setting >> (i.e. ATT will likely be the correct setting on the >> noisy low bands and PRE >> will likely be correct for 10m). Remember that the K3 >> will remember these >> settings for each band. Once you have the correct >> setup on each band it >> will automatically recall that PRE/ATT setting when you >> return to that band. >> >> 4. Now adjust the RF GAIN knob counterclockwise until >> the antenna noise on >> the meter just stops flickering on the meter. This >> will be familiar to OTs >> since this is the way we set RF GAIN many years ago on >> analog radios. >> >> 5. Now adjust your AF GAIN knob for a >> > comfortable > >> listening level (mine is >> normally 9-10 o'clock which may vary depending on what type >> of headphones >> you have). >> >> If you still don't like the amount of background noise >> compared to signal >> levels, adjust CONFIG: AGC THR to a lower setting than the >> default 5. This >> which will reduce the apparent noise level by moving the >> AGC onset point >> down and acting as sort of a noise squelch. >> >> Regarding settings for speakers, I never use them since I'm >> normally >> listening for extremely weak signals on 160m or in contests >> and I don't want >> ANY extraneous noise between my ears and the signals. >> Perhaps someone who >> uses speakers can add comments. >> >> I hope the above helps but please read K3NA's article for >> more comprehensive >> suggestions (remembering that his setup >> > is for AGC Off). > >> My general rule for all gain settings (PRE/OFF/ATT, RF Gain >> knob, AF Gain >> knob, CONFIG: AF GAIN) is LESS IS BETTER (as long as you >> can hear signals). >> This is contrary to the thinking of some but following it >> will ensure that >> you get the ultimate dynamic range performance available >> from the K3. >> >> 73, Bill W4ZV >> > > > > > > ______________________________________________________________ > 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 n7ws
On Fri, Dec 18, 2009 at 11:09 AM, Wes Stewart [via Elecraft] <[hidden email]> wrote:
My S-Meter increases monotonically with reduced RF Gain...from S0 at Max clockwise to S9+55 at Max counterclockwise. I made the assumption that everyone has done the new RF Calibration Utility implemented August 11 beginning with version 3.25 (and subsequent updates). I've also calibrated my S-Meter with an XG1. I'm not sure how current Jack Smith's note is but I see his Test Setup was dated 12 January 2009, so I'm not sure if his comments are still valid for the new RF Calibration Utility. Someone asked about my AGC settings. Here's what I'm presently using but I do vary them from time-to-time: AGC-S = 020 (but I seldom use AGC-S) AGC-F = 100 AGC THR = 006 AGC SLP = 013 AGC PLS = nor AGC HLD = 0.20 (only applies to AGC-S) AGC DCY = Soft To be honest I don't really find the AGC settings to be all that critical for my operating, which is 100% CW on 160m (until 10m opens up again). I can regularly copy weak DX signals that others have trouble hearing and I generally have low error rates in contests, so the K3's AGC can't be all that bad. Sometimes I do try turning AGC off for very weak signals but to be honest I've never been able to notice much difference. I never use NR but do have NB on most of the time (DSP t1-6, IF NAR5) outside of contests since I have some local electric fence noise. I have a variety of headphones (Heil BM-10, 2 old Heil ProSets, Extreme Isolation EX-29 and Etymotic ER6). AF GAIN = LO works well for all of these with tons of gain available. I have excellent hearing (hearing test last September) but I don't hear the 12 kHz artifacts some claim to hear. Perhaps it's because I prefer low pitch settings (300 Hz for DX and 400-450 Hz in contests). I seldom need to touch controls on the K3 in contests except for the VFO and occasionally WIDTH, which makes this rig the easiest I've ever used in contests. I also never use RIT but prefer operating in SPLIT mode simplex so I can use the big VFOA knob. FWIW & 73, Bill W4ZV |
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In reply to this post by n7ws
Wes, thanks for the insight and it's interesting someone else has the same
problem (s meter behaving oddly when rf gain backed off, plus noisy rx). In my case I had calibrated the rf gain using an external sig gen. I asked elecraft support about this and at Dale's suggestion I redid the calibration using factory defaults. This has cleared the problem with the s meter and has also removed the problem whereby the S/N reduced immediately I turned back the rf gain. Quite what the solution is for you, Wes, I'm not sure, except that doing a rf gain calibration with different levels of input signal might allow you to hit the right answer. At others' suggestions, I have also experimented with AGC parameters. I found that the rx sounded better with AGC THR=2 (the minimum), but it could do with being even lower. (I mean a lower number). Graham ----- Original Message ----- From: "Wes Stewart" <[hidden email]> To: <[hidden email]> Sent: Friday, December 18, 2009 4:09 PM Subject: Re: [Elecraft] Noisy K3 receiver "The more you turn RF GAIN back, the higher the S-Meter will read." Well, that's the way it should work, but I can assure you that with my K3 with the factory default RF Gain calibration, turning the control counterclockwise from max would cause the S-meter to increase at first, then *decrease* and then increase again as the control reached minimum gain. That is why I've said repeatedly, NOT ALL K3s BEHAVE THE SAME WAY with respect to RF gain and AGC. ______________________________________________________________ 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 David Gilbert
Thanks for your "vote of confidence."
Since this is a public forum, it's the holiday season and I'm feeling generous, I'm going to give you a pass. --- On Fri, 12/18/09, David Gilbert <[hidden email]> wrote: You clearly don't understand how AGC and gain distribution in a rig work if you really believe that automatic settings would properly cover everything from ragchewing to contesting to weak signal DXing, all under various types of noise.  The strength of the K3 is it's adaptability to almost any signal environment, but yes ... you do need to make the effort to understand how to use it. What you want is an appliance, not a rig.  It's not the K3's fault that you gave up on it. Dave AB7E ______________________________________________________________ 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 G3TCT
This is an excellent suggestion for all having the "noise" problem. Try tuning in a relatively weak signal and then adjust CONGIG: AGC THR from the default of 005 to 002. You may find a setting that keeps the signal and reduces the noise. 73, Bill |
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In reply to this post by Arie Kleingeld PA3A-2
Arie,
As Wayne explained, the K3 has plenty of audio gain, and yes, the audio gain can be advanced sufficiently to hear the internal receiver noise, and even hear it as a mild 'roaring' noise. Gains 'all to the right' is not a good way to compare two receivers - ideally one would have to compare the audio at a level where the same signal produces the same amount of audio for both receivers. You can achieve that by using a steady signal source (a signal generator is ideal) that produces a signal level near S-9 and then connect the FT1kMP audio to a computer running an audio spectrum analyzer application (like Spectrogram) which will display the signal amplitude. Do the same with the K3 and set the AF Gain to produce the same signal amplitude. You will then have the same overall gain set for both receivers. You are attempting to compare the receiver internal noise level and not the receiver gain, so for a valid comparison, the gain of both receivers must be made the same for the test. You indicated that the noise increased on your K2 when you disconnected the antenna. AGC could do that, or too high a setting of the AF Gain. If you have any signals in the receiver passband when you have the antenna connected, the AGC would have held the receiver gain down (how much depends on your AGC SLP and TH menu settings) - then when the antenna is removed, the K3 will go to full gain, and you will be hearing the internal noise at full gain. Actually noise evaluation should be done with the AGC off so its action will not influence the test outcome. My K3 has enough audio gain that I can just barely hear the internal receiver noise with the AF Gain set at about the 8:30 position.on the internal speaker if the menu AG Gain parameter is set to HI, and about the 11:30 position if AG Gain is set to LO. With a dummy load connected (or the antenna disconnected), if I leave the RF Gain at maximum and set the AF Gain to the point where I can barely hear the receiver noise, then connect an antenna, the noise level always increases - this is the reverse of your test, but it should be just as valid. The only way I can get my K3 to have almmost as much noise with the antenna removed as it has with the antenna connected is to set the AGC Threshold to its minimum value (002). My AGC Threshold is normally set at 008. As a side-point, I set my AGC SLP at 002 because that produces a response similar to that of the K2 which I liked - weak signals sound weaker, strong signals stronger and I can judge that without reference to the S-meter. If you wish to try some other tests, let me know and I will try to help. 73, Don W3FPR Arie Kleingeld PA3A wrote: > Let me throw in a penny please. > > Just for comparison: > FT1kMP : all controls full gain (except AF of course), antenna connected. > Then disconnect antenna and listen: nearly no audio, only the receiver > noise. > > K3: do the same. Difference is that when I disconnect the antenna, the noise > coming from the speaker is much louder! So the receiver noise is much > louder? I thought that that might come from the dsp design. (I think that > that is what Don meant) > > I am open for enlightenment. > > 73 > Arie > > 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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Don & all,
I was also besieged with noise. I changed my settings which I acquired, not sure because the memory is failing :-), and tried your minimum settings... my GOSH, a whole new world. I will test further, but so far on a very "noisey" 75, the radio quited right down. We forget about all the internal settings. I do not yet have the DsP upgrade but will once the 144m mod becomes available so there is only one entrance into the radio to accomplish the upgrades. 73, Bill K9YEQ K2 #35; KX1 #35; K3 #1744; mini mods ATS-3B -----Original Message----- ........................................ The only way I can get my K3 to have almmost as much noise with the antenna removed as it has with the antenna connected is to set the AGC Threshold to its minimum value (002). My AGC Threshold is normally set at 008. As a side-point, I set my AGC SLP at 002 because that produces a response similar to that of the K2 which I liked - weak signals sound weaker, strong signals stronger and I can judge that without reference to the S-meter. If you wish to try some other tests, let me know and I will try to help. 73, Don W3FPR ______________________________________________________________ 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 G3TCT
Graham, Wes,
If I have no input signal, my S-meter behaves as normally expected (S-meter increases with reduced RF Gain), BUT if I am receiving an S-9 signal AND my S-meter is in ABS mode, the behavior is similar to that which you described. 73, Don W3FPR Graham Kimbell (G3TCT) wrote: > Wes, thanks for the insight and it's interesting someone else has the same > problem (s meter behaving oddly when rf gain backed off, plus noisy rx). > > <snip> > > Graham > ----- Original Message ----- > From: "Wes Stewart" <[hidden email]> > > "The more you turn RF GAIN back, the higher the S-Meter will read." > > Well, that's the way it should work, but I can assure you that with my K3 > with the factory default RF Gain calibration, turning the control > counterclockwise from max would cause the S-meter to increase at first, then > *decrease* and then increase again as the control reached minimum gain. > > 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 Bill K9YEQ
Yes, AGC can do that. At all settings the AGC will do its job, but if
the settings are agressive, when there is no strong signal, the receiver goes to full gain and any noise becomes loud - the K3 will try to make the noise as loud as the signal you were previously listening to. I personally think the default AGC settings are too agressive, but that is only my opinion - I like my K2 AGC (despite Wayne's preference for the default settings). 73, Don W3FPR Bill K9YEQ wrote: > Don & all, > > I was also besieged with noise. I changed my settings which I acquired, not > sure because the memory is failing :-), and tried your minimum settings... > my GOSH, a whole new world. I will test further, but so far on a very > "noisey" 75, the radio quited right down. We forget about all the internal > settings. I do not yet have the DsP upgrade but will once the 144m mod > becomes available so there is only one entrance into the radio to accomplish > the upgrades. > > > 73, > > Bill > K9YEQ > K2 #35; KX1 #35; K3 #1744; mini mods > ATS-3B > > > -----Original Message----- > ........................................ > The only way I can get my K3 to have almmost as much noise with the > antenna removed as it has with the antenna connected is to set the AGC > Threshold to its minimum value (002). My AGC Threshold is normally set > at 008. As a side-point, I set my AGC SLP at 002 because that produces > a response similar to that of the K2 which I liked - weak signals sound > weaker, strong signals stronger and I can judge that without reference > to the S-meter. > > If you wish to try some other tests, let me know and I will try to help. > > 73, > Don W3FPR > > > ______________________________________________________________ > 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: 270.14.113/2573 - Release Date: 12/18/09 02:35:00 > > 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 |
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In reply to this post by Bill W4ZV
Bill,
My experience is the "other way 'round" - a low threshold makes the AGC active on a weaker signal, and in the extreme the AGC can be activated on antenna noise, and can mask weak signals. Used intelligently with careful operation of the ATT and RF Gain, this would not be a problem (your case), but for more casual operation, a higher AGC Threshold will make the K3 more quiet. 73, Don W3FPR Bill W4ZV wrote: > > Graham Kimbell (G3TCT) wrote: > >> At others' suggestions, I have also experimented with AGC parameters. I >> found that the rx sounded better with AGC THR=2 (the minimum), but it >> could >> do with being even lower. (I mean a lower number). >> >> > > This is an excellent suggestion for all having the "noise" problem. Try > tuning in a relatively weak signal and then adjust CONGIG: AGC THR from the > default of 005 to 002. You may find a setting that keeps the signal and > reduces the noise. > > 73, Bill > > 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: Noisy K3 receiver
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In reply to this post by n7ws
Wes Stewart, N7WS, wrote on Friday December 18, 2009 at 4:43 PM:
<snip> > We have DXpeditions operating on some chunk of coral that are running > wireless networks between stations and uploading their logbooks in near > real-time to the Internet via satellite yet their operators > are still > "riding the RF gain control". Something is wrong with this picture. Wes, What is wrong IMHO is that many if not most commercial receivers designed for the amateur market are designed with too much gain ahead of their roofing filter, followed by a small dynamic range IF "system" - not a good mix which requires several roofing filters of various bandwidths, and in some cases multiple loop AGC systems. A multi loop AGC scheme can cause "noise problems" if any "see-sawing" between the AGC loops takes place as the result of overshoot in any one loop, for example, certainly if the loop time constants are incorrect. No wonder then that "riding the RF gain" is required in some cases. One approach used in the design of high performance downconversion superhets is always to use negative gain ahead of the roofing filter, followed by a low noise large IMDDR3 IF system, with minimnal required AGC applied using "electronic attenuators", not current starvation of an amplifier, to protect the "weakest link", be it the DSP's ADC if used or an audio amp. The HF noise figure of such a receiver without preamp is typically 9 to 10 db. When using these high performance receivers it is not necessary to "ride the RF gain control" when digging out weak signals in the presence of QRM. 73, Geoff GM4ESD ______________________________________________________________ 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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