Re: [Elecraft] K3 Sensitivity
Hi, Frankly I'd be skeptical about all those numbers. They are way better than those measured by ARRL and Sherwood and some are a physical impossibility. The thermal noise floor (kTB) at 400Hz is -148dBm so any number at or below this is physically impossible. To me it looks like all your numbers are off by 10dB or so for whatever reason. I am not sure how you used Spectrogram to measure SNR. All you really need is the dBV meter built into the K3. Assuming it's well designed it should be ideal for measuring RMS power ratios which is what you need. The manual sheets for the XG3 generator from Elecraft has excellent instructions on how to calculate MDS using nothing more than the XG3 and the K3 itself. Of course replacing the XG3 with a professional grade HP generator will not hurt the accuracy of the results. Anyway, this doesn't really explain why you think the K3 has lost sensitivity since the installation of the general coverage bandpass filter board. When I installed mine, I noticed no such effect. If anything this filter ought to have lower loss than the per band RF filters used for in ham-band reception. AB2TC - Knut briancom wrote > Jay, > > As promised, I went ahead and measured my K3 sensitivity. It is really > a K3S-. It doesn't have the USB I/O board but has the rest of the K3 -> > K3S upgrades. There general coverage bandpass filter board is installed. > > Here are the results on 20-6M. > > The sensitivities are as expected and comparable to other rigs' > published results. They also seem to agree reasonably well with more > well equipped lab K3 results. I don't claim well equipped lab accuracy. > > Condx: > 1) SubRX off, attenuator off > 2) CW mode > 3) 400 Hz filter in > 4) Measured the S/N with Spectrogram. These numbers are based upon a 10 > db S/N ratio. That also happens to be the MDS I can hear +/- a few dB. > > On the 12,10,6M bands a 20 db S/N was measured and then subtracted 10 dB > from the result. This is to eliminate possible signal generator leakage > effects. The K3 audio output is very linear with RF signal level input > so this is a reasonable thing to do. > > BAND no preamp preamp1 preamp2 > 20-144 dBm -147 x > 17-143 -145 x > 15-143 -147 x > 12-144 -144 -154 > 10-143 -145 -156 > 6 -136 -141 -151 > > I'm not sure I believe the -15x numbers. Elecraft does say preamp 2 is > ultra low noise. > > Measurement setup: > HP-8657B signal generator with additional internal shielding. > 20 db attenuator at the generator output. > double shielded RG-400 coax to K3 antenna. > HP-8657B output verified with an HP-3586C up to 30 MHz down to -122 dBm. > Spectrogram on a Delta 44 sound card to measure S/N. > Signal measured from K3 line out. > > YMMV > > 73 de Brian/K3KO > > P.S. Switching in the second RX reduces these numbers about 3 dB. > -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Sensitivity-tp7626210p7626238.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto: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 Sensitivity
Jay, As promised, I went ahead and measured my K3 sensitivity. It is really a K3S-. It doesn't have the USB I/O board but has the rest of the K3 -> K3S upgrades. There general coverage bandpass filter board is installed. Here are the results on 20-6M. The sensitivities are as expected and comparable to other rigs' published results. They also seem to agree reasonably well with more well equipped lab K3 results. I don't claim well equipped lab accuracy. Condx: 1) SubRX off, attenuator off 2) CW mode 3) 400 Hz filter in 4) Measured the S/N with Spectrogram. These numbers are based upon a 10 db S/N ratio. That also happens to be the MDS I can hear +/- a few dB. On the 12,10,6M bands a 20 db S/N was measured and then subtracted 10 dB from the result. This is to eliminate possible signal generator leakage effects. The K3 audio output is very linear with RF signal level input so this is a reasonable thing to do. BAND no preamp preamp1 preamp2 20-144 dBm -147 x 17-143 -145 x 15-143 -147 x 12-144 -144 -154 10-143 -145 -156 6 -136 -141 -151 I'm not sure I believe the -15x numbers. Elecraft does say preamp 2 is ultra low noise. Measurement setup: HP-8657B signal generator with additional internal shielding. 20 db attenuator at the generator output. double shielded RG-400 coax to K3 antenna. HP-8657B output verified with an HP-3586C up to 30 MHz down to -122 dBm. Spectrogram on a Delta 44 sound card to measure S/N. Signal measured from K3 line out. YMMV 73 de Brian/K3KO P.S. Switching in the second RX reduces these numbers about 3 dB. On 1/29/2017 3:55 AM, jay Miller wrote: I assembled my K3/100 with the second receiver in December of 2010. The weak signal performance was much better than my original IC-756 rig. I did not install the automatic antenna tuner. I have continued to download the software changes since then. Two years ago I installed the general coverage receiver modification. I thought it was my imagination at the time but I thought had experienced a slight decrease in the primary and secondary receiver sensitivity. Today I put my Kenwood TS-480 that I had been using as a mobile in the shack. I was listing to a couple of weak strength SSB QSOs using the K3. Out of curiosity I switched over to the TS-480 and was surprised that the weak signals were more "copy-able" on the inexpensive Kenwood than on the K3. Does this indicate a problem with the RX in the K3 or is the apparent difference in the TS-480 RF gain come at the price of the definitely poorer adjacent signal rejection? __ 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 als...@comcast.net __ 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
[Elecraft] K3 Sensitivity
I assembled my K3/100 with the second receiver in December of 2010. The weak signal performance was much better than my original IC-756 rig. I did not install the automatic antenna tuner. I have continued to download the software changes since then. Two years ago I installed the general coverage receiver modification. I thought it was my imagination at the time but I thought had experienced a slight decrease in the primary and secondary receiver sensitivity. Today I put my Kenwood TS-480 that I had been using as a mobile in the shack. I was listing to a couple of weak strength SSB QSOs using the K3. Out of curiosity I switched over to the TS-480 and was surprised that the weak signals were more "copy-able" on the inexpensive Kenwood than on the K3. Does this indicate a problem with the RX in the K3 or is the apparent difference in the TS-480 RF gain come at the price of the definitely poorer adjacent signal rejection? __ 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 Sensitivity problem on 75/80 and 160 meters
Joe, Bill, and Buzz: Check RX ANT selection on 80 Meters? Of course I che Never mind. Thank the three of you for fixing the problem that has plagued me for two months. 73, Jan, KX2A __ 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 Sensitivity problem on 75/80 and 160 meters
Jan, Check your antenna selections - ANT1 vs. ANT2 or RX ANT on vs. off. The amount of attenuation you hear is about the same as the isolation between the antenna selection in the K3 (40 to 50 dB). The antenna selection is on a per band basis. 73, Don W3FPR On 3/15/2015 8:41 PM, Jan wrote: I have a K3 that works fine on all bands except 75/80 and 160. I have a backup rig, an IC-730 from the 1980's, that has 75/80 but not 160. I did an A/B with the two rigs on 80 meters, and both the S-meter and my ears tell me that signals are 5-7 S-units weaker on the the K3. S/N is clearly worse on the K3 than on the 730. Can someone clue me as to how to chase this down? Even if I have to send a board back to Elecraft, I would like to do that rather than send the radio. __ 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
[Elecraft] K3 Sensitivity problem on 75/80 and 160 meters
I have a K3 that works fine on all bands except 75/80 and 160. I have a backup rig, an IC-730 from the 1980's, that has 75/80 but not 160. I did an A/B with the two rigs on 80 meters, and both the S-meter and my ears tell me that signals are 5-7 S-units weaker on the the K3. S/N is clearly worse on the K3 than on the 730. Can someone clue me as to how to chase this down? Even if I have to send a board back to Elecraft, I would like to do that rather than send the radio. Thank you, Jan, KX2A __ 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 Sensitivity problem on 75/80 and 160 meters
Can someone clue me as to how to chase this down? The easiest, most accurate way is to actually measure sensitivity using an XG-2 or XG-3 signal generator. You can check the S-meter on 80 and 160 compared to 20 meters and calculate the MDS on each band following the method in the signal generator manual. Have you calibrated the RF gain of the rig and checked the antenna settings (ANT 1/ANT 2 if you have the KAT3 or Main/RX if you have a KXV3 installed)? Both antenna settings are saved per band as is the preamp and attenuator. 73, ... Joe, W4TV On 2015-03-15 8:41 PM, Jan wrote: I have a K3 that works fine on all bands except 75/80 and 160. I have a backup rig, an IC-730 from the 1980's, that has 75/80 but not 160. I did an A/B with the two rigs on 80 meters, and both the S-meter and my ears tell me that signals are 5-7 S-units weaker on the the K3. S/N is clearly worse on the K3 than on the 730. Can someone clue me as to how to chase this down? Even if I have to send a board back to Elecraft, I would like to do that rather than send the radio. Thank you, Jan, KX2A __ 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 sensitivity below 40 meters
I'm glad there are people like you Scott. I'll take back the term 'resonant antenna' and change it to 'good antenna' to keep folks happy. I should have included the word 'system' also. Let's end this before Eric does. Rich, n0ce - Original Message - From: Scott Manthe scott.man...@gmail.com To: elecraft@mailman.qth.net Sent: Wednesday, November 14, 2012 12:02 AM Subject: Re: [Elecraft] K3 sensitivity below 40 meters The real problem is that N0CE made his comment about resonant antennas to protect the feelings of his insecure buddies, at least one of whom reads this list, so they wouldn't be offended by the fact that his K3 hears better on 40 meters than the good equipment (read: high dollar rigs) that the rest of his group uses. To each his own. If it were up to me, I'd get a more secure group to hang out with. I tell people I know every day how well my K3 works, even if they own rigs that cost more than twice as much as the K3 does. Of course, I'm not terribly popular with those guys, either... ;) 73, Scott, N9AA On 11/14/12 12:35 AM, David Gilbert wrote: Well ... you made your statement (that even a good receiver needs a resonant antenna, and you were talking about how you could hear stations breaking in that nobody else could, remember?) to the list so I replied to the list. How is that wrong? If I reply to you offline others on the list won't realize that you are wrong and the erroneous impressions about resonant antennas never die as they should. __ 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 __ 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
[Elecraft] K3 sensitivity below 40 meters
Conventional wisdom historically has been that a receiver preamp is not used at 40 meters and below primarily because it is not needed, indeed it would typically degrade receiver performance. So why is it necessary to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
The original question was *NOT* about the K3, but the KX3 which is different than the K3 due to a different design architecture. 73, Don W3FPR On 11/13/2012 9:39 AM, k...@charter.net wrote: Conventional wisdom historically has been that a receiver preamp is not used at 40 meters and below primarily because it is not needed, indeed it would typically degrade receiver performance. So why is it necessary to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
On my FTDX-5000MP I never had the preamp on for anything below 40m all it did was increase noise. All that was ever done was to use the DNR to bring the signal up out of the noise floor a lot of the time for a signal only saw on a spot you had to bring it find it with the DNR on that frequency. As I have said this is a point that the 5000 does better than my K3's about the only one though. -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of k...@charter.net Sent: Tuesday, November 13, 2012 8:39 AM To: elecraft@mailman.qth.net Subject: [Elecraft] K3 sensitivity below 40 meters Conventional wisdom historically has been that a receiver preamp is not used at 40 meters and below primarily because it is not needed, indeed it would typically degrade receiver performance. So why is it necessary to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? __ 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 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
I think it may be due to my final comment, but first, some info. My pre-amp is off and the ATT is on 90% of the time. I seldom turn on the pre-amp. With the pre-amp off, and the ATT on, I consistently hear guys breaking in that the others in the group do not hear, and they run good equipment. They comment on it, and believe it is due to my antenna. The apex of my antenna is only 40 feet high. One of them has a 100 foot tower. I believe it is due to resonance. Read on. I would suspect antenna not resonant, or working with a swr that is not optimum for the frequency. (You need both.) Emphasis is given to swr for transmit out of concern for the finals, but I discovered years ago how important a 1.0:1 swr is for receive. Anything less is a compromise in receive performance. You say to 'hear' an S9 signal. That has me curious. S9 is RF, hearing is AF. Still pondering The K3 is calibrated for S9 at -50 uV with the pre-amp on. This may be the answer to your question. It could also be that you need to calibrate your S-meter. The XG-2 works well for that. Good luck, Rich, n0ce - Original Message - From: k...@charter.net To: elecraft@mailman.qth.net Sent: Tuesday, November 13, 2012 8:39 AM Subject: [Elecraft] K3 sensitivity below 40 meters Conventional wisdom historically has been that a receiver preamp is not used at 40 meters and below primarily because it is not needed, indeed it would typically degrade receiver performance. So why is it necessary to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? __ 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 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Preamp on K3 is 11 dB, not 20. The range, using preamp or ATT, is 20 dB. I always run the attenuator on 160 and 80 TX antennas, and the preamp on some of my listening antennas. 73, Guy On Tue, Nov 13, 2012 at 9:39 AM, k...@charter.net wrote: Conventional wisdom historically has been that a receiver preamp is not used at 40 meters and below primarily because it is not needed, indeed it would typically degrade receiver performance. So why is it necessary to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? __ 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 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
The K3 S-meter can be calibrated with either the preamp on or off. I run with SMTR MD set to ABS, and I calibrate the S-meter with the preamp off because of that. 73, Don W3FPR On 11/13/2012 12:39 PM, Richard Fjeld wrote: I think it may be due to my final comment, but first, some info. My pre-amp is off and the ATT is on 90% of the time. I seldom turn on the pre-amp. With the pre-amp off, and the ATT on, I consistently hear guys breaking in that the others in the group do not hear, and they run good equipment. They comment on it, and believe it is due to my antenna. The apex of my antenna is only 40 feet high. One of them has a 100 foot tower. I believe it is due to resonance. Read on. I would suspect antenna not resonant, or working with a swr that is not optimum for the frequency. (You need both.) Emphasis is given to swr for transmit out of concern for the finals, but I discovered years ago how important a 1.0:1 swr is for receive. Anything less is a compromise in receive performance. You say to 'hear' an S9 signal. That has me curious. S9 is RF, hearing is AF. Still pondering The K3 is calibrated for S9 at -50 uV with the pre-amp on. This may be the answer to your question. It could also be that you need to calibrate your S-meter. The XG-2 works well for 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
Re: [Elecraft] K3 sensitivity below 40 meters
In all fairness, I have to append this. I held off saying what I wanted to because I knew of someone who would be watching this reflector, and I didn't want my comments out to 'the group'. I said I believe it is due to resonance and it is as far as the antenna is concerned. I also believe it is due to the K3. I bought it for my last sun cycle, and it has been a pure enjoyment for me. I'm not a 'nectar' drinker, if you get the connection. It just wouldn't be right to not acknowledge the excellent receiver. The NR is effective for man-made noise. I would like to see it better on atmospheric noise, but I don't know if that will be possible. I bought the K3 for it's operating conveniences, and it's reputation as a good receiver which I have found to be accurate. I am especially pleased with the filtering. Since I got the P3 and can see the signals beside my passband that I am not hearing, I have been amazed. In summary, even a good radio needs a resonant antenna. Rich, n0ce - Original Message - From: Richard Fjeld rpfj...@embarqmail.com To: k...@charter.net Cc: elecraft posting elecraft@mailman.qth.net Sent: Tuesday, November 13, 2012 11:39 AM Subject: Re: [Elecraft] K3 sensitivity below 40 meters I think it may be due to my final comment, but first, some info. My pre-amp is off and the ATT is on 90% of the time. I seldom turn on the pre-amp. With the pre-amp off, and the ATT on, I consistently hear guys breaking in that the others in the group do not hear, and they run good equipment. They comment on it, and believe it is due to my antenna. The apex of my antenna is only 40 feet high. One of them has a 100 foot tower. I believe it is due to resonance. Read on. I would suspect antenna not resonant, or working with a swr that is not optimum for the frequency. (You need both.) Emphasis is given to swr for transmit out of concern for the finals, but I discovered years ago how important a 1.0:1 swr is for receive. Anything less is a compromise in receive performance. You say to 'hear' an S9 signal. That has me curious. S9 is RF, hearing is AF. Still pondering The K3 is calibrated for S9 at -50 uV with the pre-amp on. This may be the answer to your question. It could also be that you need to calibrate your S-meter. The XG-2 works well for that. Good luck, Rich, n0ce - Original Message - From: k...@charter.net To: elecraft@mailman.qth.net Sent: Tuesday, November 13, 2012 8:39 AM Subject: [Elecraft] K3 sensitivity below 40 meters Conventional wisdom historically has been that a receiver preamp is not used at 40 meters and below primarily because it is not needed, indeed it would typically degrade receiver performance. So why is it necessary to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? __ 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 __ 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 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Yes, good point. I assumed when I should have been more specific. With the P3, I have the best of both worlds. I 'presume' most K3's are adjusted from the factory per the manual with the pre-amp on, at -50 uV = S9. Rich, n0ce - Original Message - From: Don Wilhelm w3...@embarqmail.com To: elecraft@mailman.qth.net Sent: Tuesday, November 13, 2012 12:05 PM Subject: Re: [Elecraft] K3 sensitivity below 40 meters The K3 S-meter can be calibrated with either the preamp on or off. I run with SMTR MD set to ABS, and I calibrate the S-meter with the preamp off because of that. 73, Don W3FPR __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
On Tue, Nov 13, 2012 at 1:13 PM, Richard Fjeld rpfj...@embarqmail.comwrote: ...even a good radio needs a resonant antenna. = It's true that reception is often better if the antenna is matched, but this doesn't mean that the antenna has to be resonant. An antenna's resonance or non-resonance does not determine its gain or directivity. It only determines whether or not it presents a reactive load at its input terminals. If an antenna does present a reactive load, a tuner can match it so that the receiver sees the correct resistive impedance. You will hear a lot more with a non-resonant curtain, rhombic or log-periodic aimed in the right direction than you will with a resonant ground-plane. A half-hour spent with EZNec looking at the gain and radiation patterns of long-wire antennas of various lengths will dispel many misconceptions. Tony KT0NY -- http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
In summary, even a good radio needs a resonant antenna. Nah. Rick K2XT __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Particularly as far as receiving goes, that's a totally erroneous statement that has been dispelled many, many times. There is nothing magical or beneficial about a resonant antenna short of the fact that it sometimes makes it easier to match. Check out how (and how well) a Beverage antenna or one of the flag/pennant antennas work for receiving to see the fallacy of your comment. The key to a good receive antenna is having a pattern that discriminates against QRM or QRN as the case may be. As long as there is enough low noise gain after the antenna all else is misconception. Dave AB7E On 11/13/2012 12:13 PM, Richard Fjeld wrote: In summary, even a good radio needs a resonant antenna. Rich, n0ce __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Yes, I agree. Given a bit of benefit of doubt, I would think the poster would have better said, an antenna tuned to resonance rather than a resonant antenna. Many very good antennas are not inherently resonant, but resonance (and therefore good power transfer) is achieved by means of some kind of tuning mechanism. 73, Don W3FPR On 11/13/2012 6:21 PM, David Gilbert wrote: Particularly as far as receiving goes, that's a totally erroneous statement that has been dispelled many, many times. There is nothing magical or beneficial about a resonant antenna short of the fact that it sometimes makes it easier to match. Check out how (and how well) a Beverage antenna or one of the flag/pennant antennas work for receiving to see the fallacy of your comment. The key to a good receive antenna is having a pattern that discriminates against QRM or QRN as the case may be. As long as there is enough low noise gain after the antenna all else is misconception. Dave AB7E On 11/13/2012 12:13 PM, Richard Fjeld wrote: In summary, even a good radio needs a resonant antenna. Rich, n0ce __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Even that misses the point, I'm afraid. Remember that the original comment referred to the receive capability of an antenna. The only thing that matching or tuning to resonance does is improve the amplitude of the combined signal and noise feeding the rig ... it does not improve the signal to noise ratio. A good receiving antenna, however, has some pattern to it that captures the desired signal while discriminating against unwanted noise, whether the noise is man made or atmospheric. A Beverage antenna, for example, has quite a strong pattern in one direction so it has a good signal to noise ratio feeding the rig. A Beverage is pretty inefficient, though, and the desired signal is pretty weak, so typically a matching transformer (9:1 or so) is used to optimize the signal transfer and a low noise preamp (either in the rig or external) is also used ... but the signal to noise ratio is determined by the antenna independent of whether it is matched or not. I guarantee that an unmatched Beverage with enough low noise gain after it will outperform any practical resonant or matched (tuned to resonance) antenna available to hams. 73, Dave AB7E On 11/13/2012 4:29 PM, Don Wilhelm wrote: Yes, I agree. Given a bit of benefit of doubt, I would think the poster would have better said, an antenna tuned to resonance rather than a resonant antenna. Many very good antennas are not inherently resonant, but resonance (and therefore good power transfer) is achieved by means of some kind of tuning mechanism. 73, Don W3FPR On 11/13/2012 6:21 PM, David Gilbert wrote: Particularly as far as receiving goes, that's a totally erroneous statement that has been dispelled many, many times. There is nothing magical or beneficial about a resonant antenna short of the fact that it sometimes makes it easier to match. Check out how (and how well) a Beverage antenna or one of the flag/pennant antennas work for receiving to see the fallacy of your comment. The key to a good receive antenna is having a pattern that discriminates against QRM or QRN as the case may be. As long as there is enough low noise gain after the antenna all else is misconception. Dave AB7E On 11/13/2012 12:13 PM, Richard Fjeld wrote: In summary, even a good radio needs a resonant antenna. Rich, n0ce __ 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 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Okay, digest this; my budget allows an 80 meter delta loop fed with open wire and I tune it with a manual tuner. As far as my radio is concerned, it looks at a resonant antenna system allowing a maximum transfer of power on both transmit and receive. Any fault with that statement? We are way off the original post which was asking why he had to to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? Now I know why people reply off line. Rich, n0ce - Original Message - From: David Gilbert xda...@cis-broadband.com To: elecraft@mailman.qth.net Sent: Tuesday, November 13, 2012 6:12 PM Subject: Re: [Elecraft] K3 sensitivity below 40 meters Even that misses the point, I'm afraid. Remember that the original comment referred to the receive capability of an antenna. The only thing that matching or tuning to resonance does is improve the amplitude of the combined signal and noise feeding the rig ... it does not improve the signal to noise ratio. A good receiving antenna, however, has some pattern to it that captures the desired signal while discriminating against unwanted noise, whether the noise is man made or atmospheric. A Beverage antenna, for example, has quite a strong pattern in one direction so it has a good signal to noise ratio feeding the rig. A Beverage is pretty inefficient, though, and the desired signal is pretty weak, so typically a matching transformer (9:1 or so) is used to optimize the signal transfer and a low noise preamp (either in the rig or external) is also used ... but the signal to noise ratio is determined by the antenna independent of whether it is matched or not. I guarantee that an unmatched Beverage with enough low noise gain after it will outperform any practical resonant or matched (tuned to resonance) antenna available to hams. 73, Dave AB7E On 11/13/2012 4:29 PM, Don Wilhelm wrote: Yes, I agree. Given a bit of benefit of doubt, I would think the poster would have better said, an antenna tuned to resonance rather than a resonant antenna. Many very good antennas are not inherently resonant, but resonance (and therefore good power transfer) is achieved by means of some kind of tuning mechanism. 73, Don W3FPR On 11/13/2012 6:21 PM, David Gilbert wrote: Particularly as far as receiving goes, that's a totally erroneous statement that has been dispelled many, many times. There is nothing magical or beneficial about a resonant antenna short of the fact that it sometimes makes it easier to match. Check out how (and how well) a Beverage antenna or one of the flag/pennant antennas work for receiving to see the fallacy of your comment. The key to a good receive antenna is having a pattern that discriminates against QRM or QRN as the case may be. As long as there is enough low noise gain after the antenna all else is misconception. Dave AB7E On 11/13/2012 12:13 PM, Richard Fjeld wrote: In summary, even a good radio needs a resonant antenna. Rich, n0ce __ 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 __ 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 __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
Well ... you made your statement (that even a good receiver needs a resonant antenna, and you were talking about how you could hear stations breaking in that nobody else could, remember?) to the list so I replied to the list. How is that wrong? If I reply to you offline others on the list won't realize that you are wrong and the erroneous impressions about resonant antennas never die as they should. But, yes ... there is something inherently wrong with your impression that an antenna system that facilitates maximum transfer of power will also be the best receive antenna. If you reread my comment below you will see that maximum signal-to-noise ratio ... not maximum signal and noise combined ... is what makes a better receive antenna. There is lots of information on the topic of receive antennas all over the internet. You can either research it yourself so that you are able to understand it or not ... your choice. Dave AB7E On 11/13/2012 9:25 PM, Richard Fjeld wrote: Okay, digest this; my budget allows an 80 meter delta loop fed with open wire and I tune it with a manual tuner. As far as my radio is concerned, it looks at a resonant antenna system allowing a maximum transfer of power on both transmit and receive. Any fault with that statement? We are way off the original post which was asking why he had to to engage the 20 dB preamp on the K3 to get it to hear an S9 signal at the appropriate level of other receivers? Now I know why people reply off line. Rich, n0ce - Original Message - From: David Gilbert xda...@cis-broadband.com To: elecraft@mailman.qth.net Sent: Tuesday, November 13, 2012 6:12 PM Subject: Re: [Elecraft] K3 sensitivity below 40 meters Even that misses the point, I'm afraid. Remember that the original comment referred to the receive capability of an antenna. The only thing that matching or tuning to resonance does is improve the amplitude of the combined signal and noise feeding the rig ... it does not improve the signal to noise ratio. A good receiving antenna, however, has some pattern to it that captures the desired signal while discriminating against unwanted noise, whether the noise is man made or atmospheric. A Beverage antenna, for example, has quite a strong pattern in one direction so it has a good signal to noise ratio feeding the rig. A Beverage is pretty inefficient, though, and the desired signal is pretty weak, so typically a matching transformer (9:1 or so) is used to optimize the signal transfer and a low noise preamp (either in the rig or external) is also used ... but the signal to noise ratio is determined by the antenna independent of whether it is matched or not. I guarantee that an unmatched Beverage with enough low noise gain after it will outperform any practical resonant or matched (tuned to resonance) antenna available to hams. 73, Dave AB7E __ 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
Re: [Elecraft] K3 sensitivity below 40 meters
The real problem is that N0CE made his comment about resonant antennas to protect the feelings of his insecure buddies, at least one of whom reads this list, so they wouldn't be offended by the fact that his K3 hears better on 40 meters than the good equipment (read: high dollar rigs) that the rest of his group uses. To each his own. If it were up to me, I'd get a more secure group to hang out with. I tell people I know every day how well my K3 works, even if they own rigs that cost more than twice as much as the K3 does. Of course, I'm not terribly popular with those guys, either... ;) 73, Scott, N9AA On 11/14/12 12:35 AM, David Gilbert wrote: Well ... you made your statement (that even a good receiver needs a resonant antenna, and you were talking about how you could hear stations breaking in that nobody else could, remember?) to the list so I replied to the list. How is that wrong? If I reply to you offline others on the list won't realize that you are wrong and the erroneous impressions about resonant antennas never die as they should. __ 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
[Elecraft] K3 - Sensitivity on 10 Meters
During the CQWW RTTY Contest this past weekend, I got the feeling that the K3 receiver could have used some additional RF gain. I was using the 250 Hz filter with +4 dB of I.F. gain dialed in. Switching the preamp on and off produced just a barely perceptible change in the background noise. I seem to remember a previous discussion about the need for a ten-meter preamp, but haven't heard any more about it. Has anyone done a test to see if the minimum detectable signal is up to snuff on 10? Fifteen meters was better, but still less than what I expected when switching the preamp in and out. Dave Hachadorian, K6LL Yuma, Arizona __ 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
Re: [Elecraft] K3 - Sensitivity on 10 Meters
Hi Dave, Our PR10 preamp module has an MDS in the -143 to -144 range on 10 meters. It doesn't get much better than that on any ham transceiver. (Using it with a K3 requires a KXV3 or KXV3A module as well, since it gets patched through the RX ANT IN/OUT jacks.) The stock MDS of the K3 on 10 meters is typically -136 dBm. This is consistent with a radio optimized for very high dynamic range. 73, Wayne N6KR On Oct 1, 2012, at 2:13 PM, Dave Hachadorian wrote: During the CQWW RTTY Contest this past weekend, I got the feeling that the K3 receiver could have used some additional RF gain. I was using the 250 Hz filter with +4 dB of I.F. gain dialed in. Switching the preamp on and off produced just a barely perceptible change in the background noise. I seem to remember a previous discussion about the need for a ten-meter preamp, but haven't heard any more about it. Has anyone done a test to see if the minimum detectable signal is up to snuff on 10? Fifteen meters was better, but still less than what I expected when switching the preamp in and out. Dave Hachadorian, K6LL Yuma, Arizona __ 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 __ 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
Re: [Elecraft] K3 sensitivity on 10M
Changing from dummy load to 2-el quad increases the noise marginally; about 1-2 db on P3. Definitely not enough gain. I am not sure whether anything short of increased gain in RF amp would work. Perhaps one can modify the 6m external preamp to work on 10m also. The low noise made me happy. It means that the power poles are quiet and the neighbors with noisy electronics (plasma TV?) are away. Ignacy -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-sensitivity-on-10M-tp5694404p5782354.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 sensitivity on 10M
OOps. I had the antenna connected via MFJ-1026, so turning on dummy still let the reference antenna in. After switching MFJ-1026 off, turning from dummy load to 2 ell quad increases the noise level by about 5 db. Enough at this QTH. Ignacy -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-sensitivity-on-10M-tp5694404p5782409.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 sensitivity on 10M
I've had a pair of K3's for a couple of years now, but this past weekend in the CQWW SSB was their first serious test on 10 meters. I used the 1.8 filter all weekend, but when I got to 10 meters, I got the distinct feeling that I wasn't hearing enough band noise. I didn't have the time or equipment to do any measurements, but I did change the 1.8 filter gain from zero to four dB, and that seemed to solve the problem, as I perceived it. Maybe I'll go through the filter gain settings again on both radios, listening to background noise on 10 meters. If someone has the equipment to do MDS tests on 10, it would be interesting to see the results. Dave Hachadorian, K6LL Yuma, AZ . __ 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
Re: [Elecraft] K3 sensitivity on 10M
Dave Hachadorian wrote: when I got to 10 meters, I got the distinct feeling that I wasn't hearing enough band noise. I've had the same experience and have commented in the past that I thought the K3 needs to dial in a little extra gain on 10M. I've resorted to cranking CONFIG Filter Gain to +8dB but perhaps a more elegant solution could be implemented. 73, Barry N1EU -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-sensitivity-on-10M-tp5694404p5694511.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 sensitivity on 10M
Well could be possible to improve it (if necessary) for the upcoming ARRL10 contest in December? I will want to use my K3 in this contest, but with this comments I will try to compare it in 10 mts with my TS850 I used before Thank, Jorge CX6VM/CW5W -Mensaje original- De: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] En nombre de Barry N1EU Enviado el: Lunes, 01 de Noviembre de 2010 03:42 p.m. Para: elecraft@mailman.qth.net Asunto: Re: [Elecraft] K3 sensitivity on 10M Dave Hachadorian wrote: when I got to 10 meters, I got the distinct feeling that I wasn't hearing enough band noise. I've had the same experience and have commented in the past that I thought the K3 needs to dial in a little extra gain on 10M. I've resorted to cranking CONFIG Filter Gain to +8dB but perhaps a more elegant solution could be implemented. 73, Barry N1EU -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-sensitivity-on-10M-tp5694404p5694511 .html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 sensitivity on 10M
Are you confusing sensitivity with overall gain? Typically the higher frequency bands are much, much quieter than the lower frequency bands but a 0.1 uV signal will produce the same volume from the speaker on 10 (or 6) meters as it will on 80 meters (if you can hear it in the band noise :-) It's normal to turn up the gain (or engage the Preamp) on the higher frequency bands to provide some additional overall gain and, perhaps, improve the receiver noise figure so it's actually a little more sensitive (able to hear weaker signals without their being covered by internal receiver noise) than on the lower bands. Ron AC7AC -Original Message- Well could be possible to improve it (if necessary) for the upcoming ARRL10 contest in December? I will want to use my K3 in this contest, but with this comments I will try to compare it in 10 mts with my TS850 I used before Thank, Jorge CX6VM/CW5W __ 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
[Elecraft] K3 sensitivity + preamp: looking for wisdom
Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better. So...HOW does a preamp help to bring a signal out of the noise without the use of some fancy computer algorithms backed by lots of computing power? Further, does a preamp really improve sensitivity? I have yet to find a signal that I could not copy (or hear) with any preamp on vs increasing the AF gain. PS...I am talking about HF. I know that lots of guys use a preamp on 160m with their beverages, so the effect must be real...right? HOW does a dumb device do it? de Doug KR2Q ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3 sensitivity + preamp: looking for wisdom
I think the theory is that the atmospheric noise is below the receiver's detection level so the noise you hear is generated inside the rig. Add a preamp and both the antenna noise and signal come up by the same amount bringing the antenna noise up to the detection floor and boosting the signal at the same time. The overall noise floor doesn't change much if any but switched from internal noise to antenna noise. The signal, however has come up and is easier to copy. - Keith N1AS - - K3 711 - -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of DOUGLAS ZWIEBEL Sent: Monday, December 15, 2008 11:15 AM To: Elecraft Reflector Subject: [Elecraft] K3 sensitivity + preamp: looking for wisdom Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better. So...HOW does a preamp help to bring a signal out of the noise without the use of some fancy computer algorithms backed by lots of computing power? Further, does a preamp really improve sensitivity? I have yet to find a signal that I could not copy (or hear) with any preamp on vs increasing the AF gain. PS...I am talking about HF. I know that lots of guys use a preamp on 160m with their beverages, so the effect must be real...right? HOW does a dumb device do it? de Doug KR2Q ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 sensitivity + preamp: looking for wisdom
Doug, the preamp does not discriminate between signal and noise. It does not bring the signal out of the noise. It will raise the level of the signal and the noise if the noise level is very low such as happens frequently on VHF, sometimes on ten meters and occasionally on 15 meters. Preamps seldom help on the lower bands. The ten meter contest this weekend was a time where a preamp helped. I used the one in my K3. For me, most of the time the noise level was low enough that the preamp was of benefit. It raised the signal about an S unit which was enough. Part of the time the local power line noise was enough that I turned the preamp off because the noise level was moving the S meter. The best place for a preamp is at the antenna before the coax. Needless to say, this presents a lot of complications for transmitting antennas so hams usually use a preamp at the receiver. Preamps are great for receive only antennas that are far away from the shack, particularly if they are not very sensitive (such as a Beverage on 160 meters) As you observed, preamps are not very smart. They are just a transistor or two and some filtering. They are useful sometimes, harmful at others. I hope this helps. Willis 'Cookie' Cooke K5EWJ --- On Mon, 12/15/08, DOUGLAS ZWIEBEL doug...@gmail.com wrote: From: DOUGLAS ZWIEBEL doug...@gmail.com Subject: [Elecraft] K3 sensitivity + preamp: looking for wisdom To: Elecraft Reflector elecraft@mailman.qth.net Date: Monday, December 15, 2008, 8:14 AM Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better. So...HOW does a preamp help to bring a signal out of the noise without the use of some fancy computer algorithms backed by lots of computing power? Further, does a preamp really improve sensitivity? I have yet to find a signal that I could not copy (or hear) with any preamp on vs increasing the AF gain. PS...I am talking about HF. I know that lots of guys use a preamp on 160m with their beverages, so the effect must be real...right? HOW does a dumb device do it? de Doug KR2Q ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 sensitivity + preamp: looking for wisdom
DOUGLAS ZWIEBEL wrote: Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better. So...HOW does a preamp help to bring a signal out of the noise without the use of some fancy computer algorithms backed by lots of computing power? Further, does a preamp really improve sensitivity? I have yet to find a signal that I could not copy (or hear) with any preamp on vs increasing the AF gain. PS...I am talking about HF. I know that lots of guys use a preamp on 160m with their beverages, so the effect must be real...right? HOW does a dumb device do it? de Doug KR2Q There is residual noise within the receiver. By amplifying the signal, a preamp can improve the signal to noise ratio, if the noise being received by the antenna is close to the amount of noise that is generated in the receiver. Therefore preamps are most often needed on VHF and up where the atmospheric noise level is low and greater gain is needed to raise it to the point where it swamps internally generated noise. If, as I do, you live in an electrically noisy location, then a preamp may seem to make no difference at all. I do not find the K3 preamp has any benefit at all, since the S meter is always reading a couple of S points (often a lot more!) even on a dead band. Perhaps when the higher frequency bands become workable again the preamp might show some benefits. It is probably also useful on 6m. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3-sensitivity-%2B-preamp%3A-looking-for-wisdom-tp1658815p1658925.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3 sensitivity + preamp: looking for wisdom
Keith is quite right. All receivers generate internal noise in their amplifiers. The goal is to make sure this internal noise does not compete with the received signal so the only thing that limits the ability to hear weak signals is the unavoidable atmospheric or antenna noise. Of course, the amount of antenna noise you hear depends upon the filter bandwidth used. Narrower bandwidths admit less noise. That's why narrow band modes (e.g. CW, PSK31, etc.) get through when wider bandwidth modes won't. In order to keep very strong off-frequency signals from overloading the amplifier stages in the receiver, the ideal receiver has as little gain as possible before the filters that set the selectivity. But any noise generated in the very first stages of a receiver (mixer, etc.) gets amplified along with the signal and appears in the speaker or phones. On lower frequencies (up to about 10 MHz) the antenna noise in the quietest locations is still relatively high. That allows a receiver for those frequencies to be designed for best dynamic range (minimum gain ahead of the filters) and still the antenna noise will dominate, even at the narrowest filter setting. So the ability to hear weak signals it limited solely by the antenna noise and not by the receiver's internal noise. On the higher frequencies, the atmospheric (antenna) noise drops dramatically. Depending upon the noise in one's location, somewhere between 10 and 20 MHz the noise generated internally in most receivers designed for optimum dynamic range on the lower frequencies will start to compete with the antenna noise. The K3 (and K2) are no exceptions. The answer is to add more gain near the antenna using a low-noise preamplifier that boosts the signal and antenna noise levels up above the receiver's internal noise. That's why the K3 (and K2) have built-in preamplifiers that can be switched in on the higher frequencies. Low noise refers to the fact that the preamplifier has low enough internal noise that it won't compete with signals down at the level of the antenna noise. In general, the quieter (lower noise) the preamplifier is, the more susceptible to overload it becomes. And you don't want more gain than necessary ahead of the receiver's filters. Every dB of gain added reduces the dynamic range by bringing all signals and noise up nearer the clipping point of the subsequent amplifier stages in the receiver. That's why the preamplifiers are switchable. Smart ops turn them off on the lower frequencies where they aren't needed. Indeed, that's why there's an attenuator. Under extreme conditions, attenuating all the signals - wanted and unwanted alike - provides greater dynamic range and better performance, as long as the antenna noise is still greater than that generated internally in the receiver. That's a very common situation on the 160, 80 and sometimes the 40 meter Ham bands for many Hams. It depends upon their antenna and the level of the antenna noise. The built in preamplifier in the K3 does a great job on frequencies up to 30 MHz or so but it's marginal for best weak-signal reception in many locations on 6 meters. That's why the PR6 was added. It's optimized for best 6 meter weak-signal reception under most circumstances by providing enough gain to bring the very low antenna noise and signals on 6 meters up above the internal receiver noise. Ron AC7AC -Original Message- Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better. So...HOW does a preamp help to bring a signal out of the noise without the use of some fancy computer algorithms backed by lots of computing power? Further, does a preamp really improve sensitivity? I have yet to find a signal that I could not copy (or hear) with any preamp on vs increasing the AF gain. PS...I am talking about HF. I know that lots of guys use a preamp on 160m with their beverages, so the effect must be real...right? HOW does a dumb device do it? de Doug KR2Q ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm
[Elecraft] K3 sensitivity + preamp: looking for wisdom
Hi Ron, This was an -excellent- layman's language explanation about the functioning of front ends and pre-amps. Tell the boss you need an atta-boy and a raise! Merry Christmas! Ken Kopp - K0PP elecraftcov...@rfwave.net ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] K3 sensitivity + preamp: looking for wisdom
Hello Doug, Here some basics about preamps. I will try to make it short, but I could expand to pages A preamp only makes sense if the noise-figure (NF) of the preamp is better than the NF of the normal input stage (usually the normal frontend input). Each stage in a receiver (frontend, mixer, pads, amplifiers and buffers) adds his internal noise to the combination of signal and noise injected into that stage. If the noise-figure (NF) of the first stage is better then the NF of the following stage, the amplification factor of the first stage is determining if, and how much, the S/N ratio becomes better (or not). So, to stay with your words: The preamp is not some kind of intelligent amplifier selecting signal out of the noise but it should present a better signal to noise ratio to the next stage because it adds less internal (thermal) noise to the signal than the following stage. The best result in signal to noise ratio is coming out of your antenna connector (at the antenna) everything done after, is worsening the situation. The first decrease in S/N ration is due to attenuation of the coaxial cable. So the best place to put the preamp is at the antenna so the signal + antenna noise is amplified to a maximum level. The amount of noise added by the preamp and coaxial cable is only relative small compared to the amplified antenna signal. A preamp has got 1 big disadvantage: it decreases the dynamic range of the original receiver setup (with about the same number of dB's as the gain of the pre-amplifier). The best solution whatever is a frontend that has to little gain of it's own but a relative low NF (let's say 3 dB) and capable of handling BIG signals. A separate preamp that has a NF of 0,5 dB and a gain of 13 dB would be good enough to have a good overall performance (low NF and not too much gain before the first mixer stage). Most preamps in HF equipment are TOTALLY useless and only worsening the situation (but looks good on your S-meter). The discussion about the need for a low NF preamp on HF is easy for me: The less noise the preamp adds from itself (and so worsening the S/N ratio) the better it is. The effect of a low noise preamp is lessening when the atmospheric noise is higher, but the effect will never be zero! On low band the atmospheric noise is high and local signals very strong and so stressing the dynamic range of the receiver. On these bands it's sometimes better to switch the preamp off. 73's Evert PA2KW -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of DOUGLAS ZWIEBEL Sent: Monday, December 15, 2008 17:15 To: Elecraft Reflector Subject: [Elecraft] K3 sensitivity + preamp: looking for wisdom Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better. So...HOW does a preamp help to bring a signal out of the noise without the use of some fancy computer algorithms backed by lots of computing power? Further, does a preamp really improve sensitivity? I have yet to find a signal that I could not copy (or hear) with any preamp on vs increasing the AF gain. PS...I am talking about HF. I know that lots of guys use a preamp on 160m with their beverages, so the effect must be real...right? HOW does a dumb device do it? de Doug KR2Q ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 sensitivity + preamp: looking for wisdom
Ron, Your detailed explanation is one of the best that I have ever read. Although I understand the reasoning for and the performance of preamps on given HF bands, and the conditions of when to use and when to not use them, your verbiage does extreme justice to ansering the question AND describing in words most will understand the full sequence of events surrounding use or non-use of preamps at HF. Thanks for your time and effort to put forth this layman's explanation. 73, de Milt, N5IA - Original Message - From: Ron D'Eau Claire r...@cobi.biz To: 'DOUGLAS ZWIEBEL' doug...@gmail.com; 'Elecraft Reflector' elecraft@mailman.qth.net Sent: Monday, December 15, 2008 11:14 AM Subject: RE: [Elecraft] K3 sensitivity + preamp: looking for wisdom Keith is quite right. All receivers generate internal noise in their amplifiers. The goal is to make sure this internal noise does not compete with the received signal so the only thing that limits the ability to hear weak signals is the unavoidable atmospheric or antenna noise. Of course, the amount of antenna noise you hear depends upon the filter bandwidth used. Narrower bandwidths admit less noise. That's why narrow band modes (e.g. CW, PSK31, etc.) get through when wider bandwidth modes won't. In order to keep very strong off-frequency signals from overloading the amplifier stages in the receiver, the ideal receiver has as little gain as possible before the filters that set the selectivity. But any noise generated in the very first stages of a receiver (mixer, etc.) gets amplified along with the signal and appears in the speaker or phones. On lower frequencies (up to about 10 MHz) the antenna noise in the quietest locations is still relatively high. That allows a receiver for those frequencies to be designed for best dynamic range (minimum gain ahead of the filters) and still the antenna noise will dominate, even at the narrowest filter setting. So the ability to hear weak signals it limited solely by the antenna noise and not by the receiver's internal noise. On the higher frequencies, the atmospheric (antenna) noise drops dramatically. Depending upon the noise in one's location, somewhere between 10 and 20 MHz the noise generated internally in most receivers designed for optimum dynamic range on the lower frequencies will start to compete with the antenna noise. The K3 (and K2) are no exceptions. The answer is to add more gain near the antenna using a low-noise preamplifier that boosts the signal and antenna noise levels up above the receiver's internal noise. That's why the K3 (and K2) have built-in preamplifiers that can be switched in on the higher frequencies. Low noise refers to the fact that the preamplifier has low enough internal noise that it won't compete with signals down at the level of the antenna noise. In general, the quieter (lower noise) the preamplifier is, the more susceptible to overload it becomes. And you don't want more gain than necessary ahead of the receiver's filters. Every dB of gain added reduces the dynamic range by bringing all signals and noise up nearer the clipping point of the subsequent amplifier stages in the receiver. That's why the preamplifiers are switchable. Smart ops turn them off on the lower frequencies where they aren't needed. Indeed, that's why there's an attenuator. Under extreme conditions, attenuating all the signals - wanted and unwanted alike - provides greater dynamic range and better performance, as long as the antenna noise is still greater than that generated internally in the receiver. That's a very common situation on the 160, 80 and sometimes the 40 meter Ham bands for many Hams. It depends upon their antenna and the level of the antenna noise. The built in preamplifier in the K3 does a great job on frequencies up to 30 MHz or so but it's marginal for best weak-signal reception in many locations on 6 meters. That's why the PR6 was added. It's optimized for best 6 meter weak-signal reception under most circumstances by providing enough gain to bring the very low antenna noise and signals on 6 meters up above the internal receiver noise. Ron AC7AC -Original Message- Hi... The following request for information is not specific to the K3 (or even to Elecraft). Please craft your response to be generic. Despite being an active ham/contester for over 40 continuous years (but not being an ee), I just do not understand how a preamp works. It is not a smart device, so how does it know to amplify the signal and not the noise? I first used a preamp way back when (1960's) when I was a teenager...it was an Ameco job. It was more fun than useful, because I could give out big S meter reports. Later, when listening in the noise became more important to my style of operation, I never could notice a difference between putting the preamp on and just turning up the volume (many rigs with built-in preamps too). Sometimes, turning up the AF gain worked better
[Elecraft] K3 sensitivity
I am using the Elecraft XG1 signal generator to calibrate my K3's S meter. I followed the instructions (pre-amp on, filters broad, etc) but the best I do is calibrate to S-7 for 50mv. When I turn the XG1 down to 1mv the S-meter reads 1 instead of 2-3 S units. I noticed that I had to add about 4db of gain to my 400Hz 8 pole filter to compensate. Is this normal? 73 - Guy, N7ZG -- View this message in context: http://www.nabble.com/K3-sensitivity-tp18251818p18251818.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 - Sensitivity drop between Low and Hi power
Seems I've found the problem but I should wait till monday to try to fix it. As suggested by Gary at Elecraft I've checked some components and I found Q9 on the KPA3 board broken. I think Q9 is both responsible of the power instability I've found and the drop in a S point when KPA3 was enabled. I'll let the list know. Max IW0GXY Vic K2VCO wrote: max iw0gxy wrote: Hi all, I connected the XG2 signal generator to my K3 and I've injected 50microV into the antenna. I have the standard S9 but when I rise the power to 13 and up signal drop down to S8. If I turn the knob to 12W or less signal turn back to S9. I've noted this behavior on signals on air but to be sure I've used my signal generator. I do not see any change in received signal levels here when switching between low and high power. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- View this message in context: http://www.nabble.com/K3---Sensitivity-drop-between-Low-and-Hi-power-tp18165769p18171938.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] K3 - Sensitivity drop between Low and Hi power
Hi all, I connected the XG2 signal generator to my K3 and I've injected 50microV into the antenna. I have the standard S9 but when I rise the power to 13 and up signal drop down to S8. If I turn the knob to 12W or less signal turn back to S9. I've noted this behavior on signals on air but to be sure I've used my signal generator. Did someone noted the same behavior? Max IW0GXY -- View this message in context: http://www.nabble.com/K3---Sensitivity-drop-between-Low-and-Hi-power-tp18165769p18165769.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] K3 - Sensitivity drop between Low and Hi power
max iw0gxy wrote: Hi all, I connected the XG2 signal generator to my K3 and I've injected 50microV into the antenna. I have the standard S9 but when I rise the power to 13 and up signal drop down to S8. If I turn the knob to 12W or less signal turn back to S9. I've noted this behavior on signals on air but to be sure I've used my signal generator. I do not see any change in received signal levels here when switching between low and high power. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] K3 : Sensitivity
Question from today at local hamfest: On the webpage: Is it possible to phase lock the two K3 receivers? They run off the same reference oscillator and are phase locked. Do you loose sensitivity on either receiver doing this way? Not sure I understood his question, but is volume level effected? Dwight Agnew - AI4II 9335 King George Dr. Manassas, VA U.S.A. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
