K3 related - non-linear audio transformer behavior
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K3 related - non-linear audio transformer behavior
 
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I've spent the last two weeks measuring and analyzing non-linear
behavior of several audio transformers, focusing on the Tamura TTC-108 used as isolation transformers in the K3. My data and analysis is now available at http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm Jack K8ZOA www.cliftonlaboratories.com _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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Jack:
With regard to the plots under "Comparisons and Conclusions," and also under "Frequency Response Compared," is it possible to change the source Z from 600-ohms to 50-ohms and re-test? It would be an interesting exercise to see if THD (at ~ 1V RMS) and the high-end frequency response of the Bourns transformer changes significantly. Tnx! Paul, W9AC ----- Original Message ----- From: "Jack Smith" <[hidden email]> To: "'Elecraft'" <[hidden email]> Sent: Saturday, September 20, 2008 8:02 AM Subject: [Elecraft] K3 related - non-linear audio transformer behavior > I've spent the last two weeks measuring and analyzing non-linear behavior > of several audio transformers, focusing on the Tamura TTC-108 used as > isolation transformers in the K3. > > My data and analysis is now available at > http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm > > > Jack K8ZOA > www.cliftonlaboratories.com > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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 |
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Does anyone on the list have any experience using an Ameritron pulser
(ATP 100 or ATP 102) to tune an amplifier. If so, I have a few questions: Is there a practical way to connect both the pulser and a regular keyer to the K2 key jack so that you can use either device, but avoid having one device affect the other? Can you get the same effect as the ATP by simply sending a string of dots from the keyer? If so, is there a particular combination of dot spacing and code speed that is best suited to get a K2 to generate the waveform necessary to tune an amplifier by the "pulser" method? Are these pulsers just a gimmick, or is this really a good way to tune an amplifier? Thanks & 73, Steve AA4AK _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Stephen W. Kercel wrote:
> Does anyone on the list have any experience using an Ameritron pulser > (ATP 100 or ATP 102) to tune an amplifier. No, but... > Is there a practical way to connect both the pulser and a regular keyer > to the K2 key jack so that you can use either device, but avoid having > one device affect the other? Probably you could simply parallel the output of the pulser device with a straight key. If you are using a paddle and the K2's internal keyer, then you could use the K2's 'autodetect' feature (look this up in the manual). > Can you get the same effect as the ATP by simply sending a string of > dots from the keyer? Probably the pulser would generate relatively shorter pulses than the 50% duty cycle of keyer dits. But you could probably get away with using a keyer. See below. > If so, is there a particular combination of dot spacing and code speed > that is best suited to get a K2 to generate the waveform necessary to > tune an amplifier by the "pulser" method? > > Are these pulsers just a gimmick, or is this really a good way to tune > an amplifier? The idea is this: to tune an amplifier properly for SSB, you need to tune it so it will be loaded properly under peak power conditions. One way to do this would be tune it in CW mode, increasing drive to produce a CW signal equal to the SSB peak power level. But continuous operation at this level would exceed the tube's dissipation ratings; so by sending a series of short pulses, you can adjust the amplifier at peak plate current without excessive heating due to the low duty cycle. When tuning for CW, it isn't necessary since you are only loading the amplifier to its rated CW plate current, which is lower than the peak SSB current. Of course, many amplifiers are not rated for 100% key-down output for any length of time, so tuning should be kept short. Or you can use a keyer or pulser to reduce the dissipation further. When using a keyer, speed doesn't matter since duty cycle is determined by dot/space ratio. But if you can reduce the weight, that would reduce the duty cycle. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Interesting to note that in QST magazine's review of a super whizbang,
thermonuclear commercial transceiver from Rohde and Schwartz in the October issue of QST, the receiver they referenced its intermod performance to is.......the K3. NICE! John, N6AX K3 567 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Interesting indeed. The comparison they quote is the IMD
dynamic range at 5 KHz spacing, which the R&S wins. But take a look at the 2 KHz spacing - the K3 trounces the R&S. 73, john WA1ABI K3 #795 > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]]On Behalf Of John Klewer > Sent: Saturday, September 20, 2008 11:43 AM > To: 'Elecraft' > Subject: [Elecraft] K3 vs. Rohde and Schwartz > > > Interesting to note that in QST magazine's review of a super whizbang, > thermonuclear commercial transceiver from Rohde and Schwartz in the > October issue of QST, the receiver they referenced its intermod > performance to is.......the K3. > > NICE! > > John, N6AX > K3 567 > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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 |
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In reply to this post by Stephen W. Kercel
Thank to various responders.
73, Steve AA4AK _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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In reply to this post by P.B. Christensen
Paul:
I've revised my non-linear transformer page in two respects: 1. Added the plot you requested. (Almost at the bottom of the page) 2. Added square wave ringing data for four transformers, although I am not at all convinced that square wave ringing is an appropriate figure of merit for a transformer used in a narrowly bandwidth limited communications receiver. The page is: http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm Paul Christensen wrote: > Jack: > > With regard to the plots under "Comparisons and Conclusions," and also > under "Frequency Response Compared," is it possible to change the > source Z from 600-ohms to 50-ohms and re-test? > > It would be an interesting exercise to see if THD (at ~ 1V RMS) and > the high-end frequency response of the Bourns transformer changes > significantly. Tnx! > > Paul, W9AC > > ----- Original Message ----- From: "Jack Smith" > <[hidden email]> > To: "'Elecraft'" <[hidden email]> > Sent: Saturday, September 20, 2008 8:02 AM > Subject: [Elecraft] K3 related - non-linear audio transformer behavior > > >> I've spent the last two weeks measuring and analyzing non-linear >> behavior of several audio transformers, focusing on the Tamura >> TTC-108 used as isolation transformers in the K3. >> >> My data and analysis is now available at >> http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm >> >> >> Jack K8ZOA >> www.cliftonlaboratories.com >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> 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: [hidden email] > 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: [hidden email] 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: K3 related - non-linear audio transformer behavior
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Jack,
Thanks for the research - very interesting and it looks like a simple fix to improve the performance of the K3 significantly. You've got me wondering now though about DATA-A modes. As the K3 uses the same transformer for line in your work suggests that the transmit performance will be affected by the sound card output impedance - worth considering at least. Cheers, Paul M1PAF |
Re: K3 related - non-linear audio transformer behavior
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Indeed, similar harmonic and IMD distortion are created inside the LINE
IN transformer. The question is their level and importance. The LINE IN transformer, however, is fed by a 10:1 voltage divider, 604R in series with 62R shunted across the transformer primary. This arrangement provides a lower drive impedance to the transformer, around 56 ohms as a matter of fact. (Assumes the LINE IN port is driven by a low impedance source, which I believe is the case for the typical sound card output.) 56 Ohms is low enough to see significant THD improvement over a straight 604 ohm series resistor according to my measurements. It should be possible to measure harmonics generated by the input transformer, perhaps using the monitor function. I'm too far behind on other projects to work on it at the moment, however. Jack Paul Fletcher wrote: > Jack, > > Thanks for the research - very interesting and it looks like a simple fix to > improve the performance of the K3 significantly. You've got me wondering now > though about DATA-A modes. As the K3 uses the same transformer for line in > your work suggests that the transmit performance will be affected by the > sound card output impedance - worth considering at least. > > Cheers, > Paul M1PAF > Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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In reply to this post by Jack Smith-6
The usefulness of the square-wave response plots (as you and I have
conducted) relies primarily on the complexity of the received waveform and system bandwidth. Even in the case of a CW square-wave-like signal, a gently sloping rise/decay time (e.g., raised-cosine CW waveform), greatly reduces occupied transmitted bandwidth and the square-wave impulse response of the transformer becomes less meaningful. OTOH, if there was to exist some form of data mode in which short rise/fall times are required, then a wider, flatter, overall receive bandwidth is required. Presently, I know of no such common data modes for amateur use, but this may apply to some commercial and/or military data modulation methods. Regardless of whether this is an issue or non-issue for amateur use, I have demonstrated (on the Elecraft mail list through Yahoo) that the problem is cleanly solved in even the cheapest datacom transformers through a simple termination of the secondary winding. The peace of mind of knowing that a sound card will not be over-driven by a brief spike in transformer overshoot is certainly worth cost of a single resistor between the transformer and sound card input. Paul, W9AC ----- Original Message ----- From: "Jack Smith" <[hidden email]> To: "Paul Christensen" <[hidden email]> Cc: "'Elecraft'" <[hidden email]> Sent: Saturday, September 20, 2008 6:42 PM Subject: Re: [Elecraft] K3 related - non-linear audio transformer behavior > Paul: > > I've revised my non-linear transformer page in two respects: > 1. Added the plot you requested. (Almost at the bottom of the page) > 2. Added square wave ringing data for four transformers, although I am not > at all convinced that square wave ringing is an appropriate figure of > merit for a transformer used in a narrowly bandwidth limited > communications receiver. > > The page is: > http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm > > Paul Christensen wrote: >> Jack: >> >> With regard to the plots under "Comparisons and Conclusions," and also >> under "Frequency Response Compared," is it possible to change the source >> Z from 600-ohms to 50-ohms and re-test? >> >> It would be an interesting exercise to see if THD (at ~ 1V RMS) and the >> high-end frequency response of the Bourns transformer changes >> significantly. Tnx! >> >> Paul, W9AC >> >> ----- Original Message ----- From: "Jack Smith" >> <[hidden email]> >> To: "'Elecraft'" <[hidden email]> >> Sent: Saturday, September 20, 2008 8:02 AM >> Subject: [Elecraft] K3 related - non-linear audio transformer behavior >> >> >>> I've spent the last two weeks measuring and analyzing non-linear >>> behavior of several audio transformers, focusing on the Tamura TTC-108 >>> used as isolation transformers in the K3. >>> >>> My data and analysis is now available at >>> http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm >>> >>> >>> Jack K8ZOA >>> www.cliftonlaboratories.com >>> >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> 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: [hidden email] >> 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: [hidden email] 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: K3 related - non-linear audio transformer behavior
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On Sun, 21 Sep 2008 09:11:22 -0400, Paul Christensen wrote:
>the square-wave impulse response >of the transformer becomes less meaningful. As long as there is impulse noise, the square wave response of the line out transformer is definitely relevant! As the folks at Elecraft have noted, the primary function of the Line Out is to drive data decoders of one sort or another. Those decoders see signal plus noise. Any distortion in the transformer is additional noise as far as the decoder is concerned. The square wave response of the circuit is simply another way of LOOKING at those distortion products. The analysis of the K3 Line Out that I did back in June using band noise as a source of excitation show the same problems as Jack's analysis using very different signal sources, but my excitation, being broadband, exposes the IM distortion as apparent broadening of the filter skirts. Jack measures IM using traditional two-tone methods. In other words, we both see the same problems using very different methods to study them. Those of us working in pro audio learned long ago that broadband noise (we use pink noise) is a VERY powerful analysis tool. 73, Jim Brown K9YC Audio Systems Group, Inc. _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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Have you considered the difference between hitting a transformer with a
fast rise / fast fall square wave and hitting it with one that is narrowly band limited? Ignoring for the moment the difference in filter shape between Gaussian and the complex shape of the K3 crystal and DSP filters, the rise/fall time of a perfect square wave fed into a Gaussian filter is 0.34/BW, or for a 1 KHz bandwidth, 340 microseconds. I have not yet measured but hope to later today, the transformers with a slow rise/fall waveform. A rather different story can be found, I suspect, in other audio applications where the source bandwidth may easily be 20 KHz or greater, yielding a rise/fall of 17 us or less. The slowest ringing rate I found was around 125 KHz, or 8 us for a period. I can see how that might be excited by a 17 us rise/fall square wave. I just don't see the same effect occurring with 340 us rise/fall "square wave." I use quotes around "square wave" because that leads to the image of a waveform with an abrupt rise/fall which is not the case where the bandwidth is limited to a few hundred Hz or a KHz at most. That's why I question the applicability of a ringing test with a square wave having a rise/fall time measured in nanoseconds, as the audio that makes it through the K3's crystal and DSP will not remotely resemble that waveform. Jack K8ZOA Jim Brown wrote: > On Sun, 21 Sep 2008 09:11:22 -0400, Paul Christensen wrote: > > >> the square-wave impulse response >> of the transformer becomes less meaningful. >> > > As long as there is impulse noise, the square wave response of the > line out transformer is definitely relevant! As the folks at > Elecraft have noted, the primary function of the Line Out is to > drive data decoders of one sort or another. Those decoders see > signal plus noise. Any distortion in the transformer is additional > noise as far as the decoder is concerned. The square wave response > of the circuit is simply another way of LOOKING at those > distortion products. > > The analysis of the K3 Line Out that I did back in June using band > noise as a source of excitation show the same problems as Jack's > analysis using very different signal sources, but my excitation, > being broadband, exposes the IM distortion as apparent broadening > of the filter skirts. Jack measures IM using traditional two-tone > methods. In other words, we both see the same problems using very > different methods to study them. > > Those of us working in pro audio learned long ago that broadband > noise (we use pink noise) is a VERY powerful analysis tool. > > 73, > > Jim Brown K9YC > > Audio Systems Group, Inc. > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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: [hidden email] 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: K3 related - non-linear audio transformer behavior
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On Sun, 21 Sep 2008 13:31:00 -0400, Jack Smith wrote:
>Have you considered the difference between hitting a transformer with a >fast rise / fast fall square wave and hitting it with one that is >narrowly band limited? That's one of the virtues of my measurement method -- it looks at the response of the transformer with band-limited noise as the signal source, and the band-limiting is the filters in the K3. Jim _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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In reply to this post by Jack Smith-6
> That's why I question the applicability of a ringing test with a square
> wave having a rise/fall time measured in nanoseconds, as the audio that > makes it through the K3's crystal and DSP will not remotely resemble that > waveform. Agreed Jack, if the DSP and/or AF stages truly limit impulses through the transformer. To Jim's point, ignore the modulation type for the moment and consider an impulse noise such as that created by the start of light switch or AC motor. If the system received BW is wide enough (e.g., selecting the K3's 6 kHz, or especially the 12 kHz filter), I suspect that transient impulse response becomes meaningful. I have not yet tried to sweep the K3's audio section beyond 4 kHz and the DSP and/or audio sections may preclude an audio response beyond that point. One way of testing this is to turn on/off various types of real noise sources as a function of selected filter BW and while observing a scope on the output of the line-out transformer, record the differences in peak values with and without terminating resistance on the transformer secondary -- taking into account any level difference created by the addition of the terminating resistor. Paul, W9AC _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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Paul, Looking at the Line Out with noise from an Elecraft N-Gen indicates the K3 audio is quite dramatically band limited. With the maximum DSP high cut frequency and the 13 KHz first IF filter, broadband detected noise in either AM or SSB drops 45 dB between 4 KHz and 4.2 KHz with a further 15 dB roll off between 4.2 KHz and 9 KHz where it reaches the noise floor of the measuring device. The HF limit for data modes is also 4 KHz - depending on data sub-mode and center frequency. The HF limit for CW is approximately 2.5 KHz with the highest available "Spot" frequency and center frequency (shift). I think is it safe to treat the audio as band limited ... 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Paul > Christensen > Sent: Sunday, September 21, 2008 4:51 PM > To: Jack Smith; Jim Brown > Cc: Elecraft List > Subject: Re: [Elecraft] K3 related - non-linear audio > transformer behavior > > > > That's why I question the applicability of a ringing test with a > > square > > wave having a rise/fall time measured in nanoseconds, as > the audio that > > makes it through the K3's crystal and DSP will not remotely > resemble that > > waveform. > > Agreed Jack, if the DSP and/or AF stages truly limit impulses > through the > transformer. To Jim's point, ignore the modulation type for > the moment and > consider an impulse noise such as that created by the start > of light switch > or AC motor. If the system received BW is wide enough (e.g., > selecting the > K3's 6 kHz, or especially the 12 kHz filter), I suspect that > transient > impulse response becomes meaningful. I have not yet tried to > sweep the K3's > audio section beyond 4 kHz and the DSP and/or audio sections > may preclude an > audio response beyond that point. > > One way of testing this is to turn on/off various types of real noise > sources as a function of selected filter BW and while > observing a scope on > the output of the line-out transformer, record the > differences in peak > values with and without terminating resistance on the transformer > secondary -- taking into account any level difference created by the > addition of the terminating resistor. > > Paul, W9AC > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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: K3 related - non-linear audio transformer behavior
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On Sun, 21 Sep 2008 20:42:27 -0400, Joe Subich, W4TV wrote:
>I think is it safe to treat the audio as band limited That's like saying a driver is slow. How slow? Bandwidth limiting CHANGES the complex impulse response of the system. It does not make it not matter, or benign, just DIFFERENT. And the bandlimiting is quite variable, thanks to the design and implementation of K3 operating controls of the DSP. Also, note that the impulse response is complex -- that is, if we looked at it as a frequency response it would have a phase response too. One of the important and complex problems that Lyle has to solve (and he's solved it pretty well if he doesn't hit the transformers, according to my ears) is a nice phase (time) response. Jim K9YC _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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