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Does anyone want a copy of the January/February 2025 issue of QEX? The ARRL sent me two copies. It has the tinySA tracking generator design article in it. Of so *respond to me privately* at kc0wjn at gmail dot com Responses to the list will be ignored. The magazine is free; shipping cost from 32754 USA to be paid to me by PayPal F&F (the shipping cost using USPS Media Mail is probably trivial). DaveD KC0WJN

All, The extra copy of QEX has been spoken for. DaveD KC0WJN

On 1/29/25 17:33, Reginald Beardsley via groups.io wrote: > A battery powered OSHW 1 GHz active probe to which I could connect anything via SMA would be hugely valuable. There are some > awesome instruments which are encumbered by the lack of active probes. They were built for a different use case, testing disk drives. On 2/2/25 16:25, Reginald Beardsley via groups.io wrote: > So if some folks will design and validate an active probe module designed around this or similar, I'll order prototypes and test them. > > If someone familiar with the openEMS package can simulate a PCB layout, I can verify the simulations. I've also got a machine that > can run them. No issue with making boards to test the simulations. I've done one OSHW project and earned maybe $2.60/hour. This could be fun and low time drain though... But not quick -- I have too many other projects going. Who else is interested? I can do the layout with pcb-rnd sch-rnd for any kind of vias or layers or stripline or ?. John Griessen compiling OpenEMS...

Just because it took so long to finally do it. I took the Tech section and passed it yesterday. 35/35 but a minor miracle with a wonky tablet to take the exam on. Many thanks to the VEs in Russellville. I was totally clueless of the FCC exam protocol which was nearly catastrophic. No official response yet, but I assume that's coming. After years of procrastination, I certainly can't complain about a day of delay. Really weird exam experience relative to 40-50 years ago. Paper & #2 pencil forever! I'll request that for parts 3 & 4. Hope to work some of you in the next year. Have Fun! Regq

For 10 years I built the Gnu utilities and everything else using Gnu make without the least problems. I chose to do that because make was different on many systems I was supporting. This made it easy to define the various defines for things like ar(1), etc. I used "uname -a" to select which set of definitions to use at the start of my standard Makefile template. The abomination that X propagated, imake, took fewer than 100 lines and expanded it into thousands. The fatal flaw being the expectation that the cpp(1) was the same everywhere. Eventually imake carried around it's own version of cpp(1). I do not like Linux/Gnu because the current generation of developers arbitrarily choose to drop or modify various command line options to basic tools. The hallmark of Unix in the old days was stability. The next release would not break *anything* developed on the previous release except workarounds for bugs. ' In my view, a user bug report is a significant black mark on one's skills as a programmer. I wrote a pair of 15 kLOC libraries which never had a bug found in 6 years of supported use and another 6-8 years unsupported. Every time they were compiled a comprehensive test suite fed it *all* possible inputs and checked that it responded to correctly to *all* possible user errors. One library did need a single change. I tested errno after for a call to getcwd(3c). A subsequent Solaris release failed to set errno correctly. I always set errno = 0 prior to calls which set it. The person who fixed it decided that if getcwd returned a null pointer that was an acceptable workaround and inserted a #ifdef for Sun systems. That code compiled on 6 systems, though it was only supported on 3 for the simple reason that the HP users declined to pay for verifying the test suite. The other 2 systems were built by me one afternoon when I didn't have anything to do. As for the SunOS 32 to 64 bit transition, that merely required setting the proper #defines for large file support which were very well documented. I don't recall any other changes besides trivial things such as replacing "int" with "long" if you actually needed large file support. On Tuesday, July 9, 2024 at 08:29:17 PM CDT, Chuck Harris <cfharris@...> wrote: Well, looks like you have an axe to grind, so I won't get into it much with you. Open source software has to cater to the characters that create it. I have only used sagemath compiled to 64 bit on linux, so your complaint about that is dated. The configure package, written by Larry Wall, makes tests like for the name used on the sh script. Sometimes sh is sh, other times it is borne shell, or korn shell, or something totally different aliased as sh... Likely, nothing to do with Sagemath. There are things that need work, but at least they don't charge you to beta test their software. Nothing is stopping anyone from forking the project, and doing it themselves. I'd love to see your fork of the project. Try that with mathematica. In anycase, as flawed as you think the project is, I would bet that it can easily run a version of Reg's filter code. -Chuck Harris

Intellectual integrity requires that one admit when one is incorrect and not obfuscate the argument with irrelevant details to confuse and intimidate the other party in the discussion. There is no shame in being wrong. It happens to everyone. How one acts matters. Introducing obscure and irrelevant topics into a discussion is the hallmark of the poseur. It is also a display of complete contempt for the audience. The most extreme insult possible. I did not like writing my reply to Mr. Marks. But having suffered such people at work I'm certainly not going to tolerate it here. The 5 years I spent getting a solid liberal arts undergraduate degree has served me well. My sole regret is I didn't take more math. I had a lot of catch up to do in grad school. Have Fun! Reg

For the simple reason that I am more accustomed to problems in optics and elastic wave propagation, I did not think to consult the superb "Theory and Computation of Electromagnetic Fields" by JIang-Ming Jin which I have in the 2nd edition. Jin provides a very clear description of the properties of metamaterials in section 4.2.5 and plane wave reflection and transmission between right and left handed media in 4.4.4 including a figure showing the geometrical optics approximation to a left handed slab embedded between two right handed half spaces with a point source in the right handed medium. If one takes the normal definition of refractive index as the ratio of the phase velocity, this does indeed result in a negative refractive index. The power flows away from the source, but the phase velocity is sign reversed in a left handed medium. Therefore my assertion that the refractive index can never be negative is incorrect. The topic of the reflection and transmission characteristics of metamaterials is quite interesting and I welcome further discussion. However, that does not change my assessment of Daniel Marks' post. I was very specific in my initial post that the issue of concern was minimum phase vs zero phase impulse response filters. That issue is of major importance in the digital filtering in a DSO. All the DSOs I have examined including recent high end models from Keysight and Rohde & Schwartz employ a zero phase sinc interpolator and produce non-causal displays when fed a 100 ns minimum phase impulse. Have Fun! Reg theory in

As it is likely that most, if not all, list members have not read "A Mathematical Introduction to Compressive Sensing" by Foucart and Rauhut, I though it useful to provide a bit more detail. In the solution of Ax=y, if x is sparse and A possesses the RIP, then an L1 solution for x is identical to the L0 solution. If y consists of the sum of a small number of columns selected from an A matrix with the RIP, David Donoho proved in 2004-09 that if and only if a sparse solution to Ax=y existed it was the L0 solution. A solution is not guaranteed to exist, but the probability of such a case is very low and well defined. RIP means that *any* combination of columns in A cross correlated with *any* other combination of columns from A has zero correlation (near zero in the case of finite lengths of the series). This is inherently an NP-hard problem and thus one cannot directly prove that an A matrix possesses the RIP. But if you can find an L1 solution to Ax=y for the sum of an arbitrary choice of a small number of columns then the matrix has the RIP. Otherwise a solution would not be obtained. By definition, an A matrix which is constructed from a purely random series possesses the RIP. By using such sequences for the DSSS carrier modulation as described in the recent thread I started one can readily meet the detection criteria I listed in the attachment to the first post and all the DSSS sequences are orthogonal. Have Fun! Reg

When I was living in Houston I had 2 VCRs die, each after about a year of light use. I took one apart to strip anything useful and observed that the entire board was covered with flux which is hygroscopic. Houston is humid. I was in the process of moving and throwing out junk, so I simply made a mental note of it. I have a 20 year old Aiwa CD/cassette/radio that I use to play CDs while I play guitar. About 10 years ago the system stopped working. I opened it up and removed flux residue near the MCU at which point it worked again. However after a few months it quit with the same problem. I repeated the process focused on flooding the underside of the MCU with IPA. Never have had a problem since. Until I returned from FDIM and found the remote no longer worked. Worked for 20 years and just quit. Battery swap didn't help. After cleaning the solder flux from the remote it now works properly with the old cells. My point being that it worked for 20 years and failed because the board had not been cleaned. Eventually there was enough conductance that the parasitic capacitance degraded the data lines to the MCU. Three parts, MCU, cap and LED plus the elastomer keypad. Failed "part" was the flux residue. Now when I open up anything and see flux I wash it off. It may not be a problem now, but I know from experience it will eventually. All of the consumer kit repairs I've done in the last 15 years have been flux residue induced. Sole difficulty has been internal assemblies which are too complex to make it worth the effort of getting access to the board. Have Fun! Reg

Of possible interest ? Solid state replacements for tubes in some common older Ham tube Rx : -- A single common FET is used for each tube, in these Rx. MPF102 : JFET VHF Amplifier ( inexpensive, eBay ) -- A small Rf choke is needed for @tube replacement. they can easily be wound on the Rf choke winding machine, Reg spoke about earlier. ( Or you can buy them from Charles for $1@ ; Charles provides a 1pg instruction sheet for DIY ) A variety of small Choke Forms can be used, purchased on eBay. Contact: Charles Smith: did this to the BC-348, R-390a , BC-348 & R-392 and also done for a Hammarlund. KV4JT charlessmi1@... ( very well written, paper Manuals @ $7 to $14 per radio , describing in detail all the steps necessary for conversion ): The R-392 conversion video is the most interesting: Direct Plug-in SS tube replacement modules with little modification to the radio ! ( while the BC-348 & R-390 require small mods done, inside the radios ) See: https://www.youtube.com/@charlessmith833/videos BC-348 ( three (3) different video's for the different versions ): https://www.youtube.com/watch?v=Ah8uD6ADS6Y https://www.youtube.com/@charlessmith833/videos R-390a: pat1 & part2: https://www.youtube.com/watch?v=RRZ04OKV9pQ Rf chokes for most SS tube conversions: How to wind your own ! https://www.youtube.com/watch?v=PtUkBnds01k R-392 SS Conversion: https://www.youtube.com/watch?v=6E45caVWjEo rick

As I had not made any mention of this group except to a single person, I've been a bit surprised at the number of subscribers. I'd like to ask that members make their first post to this thread. How much you say is up to you. The main purpose is so someone replying to a post of yours can have some idea of the appropriate level with which to respond. This is not a "mine's bigger than yours" contest. It's intended to preclude PhD level responses which are incomprehensible to the OP as well as the reverse. I ask that members be aware of the knowledge level of the person to whom they are responding and adjust their reply to suit the intended reader. My Dad used to say if you can't explain it to a 12 year old you don't really know what you're talking about. Have Fun! Reg

I'm arranging for a SIG meeting room at FDIM. Probably Thursday. I've left all the details to David Cripe. I've requested a whiteboard only. If someone needs something else, please contact me or David Cripe. Have Fun! Reg

https://harbachelectronics.com/

Hoping to stimulate some discussion on Old Ham Tube Linear Amps: Are there any experienced with the various Tube Amp issues, ... such as Arcing and Band SW, coil, capacitor & tube and HV Xfrmr destruction in these amplifiers ? I am beginning to refurbish two old Heathkit Linear Amps: the SB-1000 ( similar to the AL-80) & the SB-200. Scouring the Web looking for information on refurbishing issues and modifying old Heathkit Ham Linear Tube amplifiers quick summary: PS Cap board Metering board /Bias Soft-Key Soft-Start Parasitic's Glitch resistor HEC HV Caps Self-biasing of relays "Corona Washer " QSK new tubes ... poor solder joints (expected) Band Sw issues, etc. There are plenty of Ham Blogs on the SB-200 & SB-220, ... but fewer on the SB-1000 & HL-2200. Articles by Richard Measures, and others, some with theory, discussion, diagrams, photos , and, as with anything, some miss-information and some corrections. There are a lot of YouTube videos, and AmpRepairGuy.com has some videos of his repairs. Likely others , all requiring sifting the information and reasoning. Harbach Co. & CTR Engineering Kits, parts for Mods (depending on the Amp Model): Having good instruction, kits, PCB's and downloadable .pdf's at both of these two web sites: https://www.ctrengineeringinc.com/ https://harbachelectronics.com Possibly the Richard Measures (SK) Amp Forum, has some priceless, sometimes buried help: The "search" bar { below } can still dial in the query: example: http://lists.contesting.com/archives//cgi-bin/namazu.cgi?query=SB-1000+Door+Knob+Capacitor&submit=Search%21&idxname=Amps&max=20&result=normal&sort=score http://lists.contesting.com/archives//cgi-bin/namazu.cgi?query=SB-200+Band+Switch&submit=Search%21&idxname=Amps&max=20&result=normal&sort=score And, .... there seem to be some PCB's from W7RY , although I have not been successful getting adequate answers or actually purchasing the PCB's thanks,

Ultimately, the time-bandwidth-power product of a communications protocol must exceed noise by a suitable margin in order for the signal to be detected reliably. By design, the antenna signal input level of a GPS receiver is 54 dB below the noise floor of the receiver front end. With a liberal application of time and BW, the receiver achieves over 60 dB processing gain. I should note that is not 20-30 dB below the noise, merely 6 dB or so. The human ear is not phase sensitive. We do no hear zero mean white noise as silence. We perceive the absolute amplitude. So the noise we perceive is the average of that. The sole difference between integrating over a dit frame and the mean value is dividing by N. Neither has any processing gain in the sense of raising the signal above the noise. It does allow constructing a non-linear filter which appears to recover signals below the noise level. In fact it is a 2 dimensional filter. A frequency and time domain operator. The main advantage is the ability to set a detection threshold which is below human hearing discrimination. The big gain in clocked Morse is being able to null the noise without predicting it at signal levels below human audio discrimination. The virtue of clocked Morse is every jurisdiction that allows amateur radio allows Morse. Thus the gain from optimizing Morse by clock synchronization. Statistically, being a few standard deviations above the mean noise over a 1-10 second dit frame is a very sensitive discriminator. One only need to look at the QRSS distance records to confirm this. Have Fun! Reg

Aligning the dit frame is a classic application of the Fourier shift theorem. A shift in time is a multiplication in the complex frequency domain. If one takes the DFT of the series [1,0,0,0,0,0,0,0,0,0,0] it will have a constant amplitude which is entirely real. The imaginary part will be zero within roundoff error. If we do the same thing with [0,0,0,0,1,0,0,0,0,0,0] the magnitude will still be constant, but there will be a phase shift at each frequency and the real and imaginary magnitudes will change from frequency to frequency in a constant increment between steps in frequency. It's important to recognize that the series above are not pure impulses, but rather are sin(x)/x. One need only apply a half sample phase shift to see this. The zeros result from the zero crossing of the sinc(x) function being zero at those sample times. The width of the sinc(x) lobes is determined by how long the series is. Synchronization requires shifting a time gate at the receiver by an arbitrary unknown amount comprised of synchronization differences between the sender and receiver clocks and propagation delay. The classic way to do this is by multiplying the received signal with a stored, synchronized replica and then doing a linear regression on the phase to determine the delay, dT. Note that dT is *not* constrained to be an integer number of master clock periods. That must be addressed in the processing. The synchronization problem is central to all spread spectrum methods whether direct sequence or frequency hopping. An early worker in the field named Gold generated sets of random binary sequences whose autocorrelations had minimal side lobes and cross correlations had minimal peaks. These are known as "Gold codes" in his honor. A naive approach is to sync on a square wave train series of dits. This has arguably the worst possible autocorrelation. It's a series of triangles which increase in height, but not width to a peak value and then decline in similar fashion. In the presence of noise the central peak becomes a distorted blob. A Gold code is similarly degraded, but provably less so than any other symbol of similar length and provides a more reliable estimate of dT from the linear regression on the phase. Once the sender and receiver are synchronized they can start decoding characters. However, the path delay will vary in manners which will gradually break the sync. The remedy for that is to periodically use the shift theorem and the DFTs of the characters to update dT. All of this is computationally cheap. High sample rates for the phase determination are not required. So by downsampling the receiver output one can use shorter FFTs without losing resolution of dT. I've seen 48 channel 4 ms sample data analyzed to show the multiplexer skew which was 83.333 microseconds. Questions? I very much agree with George Herron's characterization of CCW as a mental dodecahedron. You really have to understand the different views to fully grasp it. NB There will be a CCW/QRSS SIG at FDIM. Details to be confirmed, but probably Thursday. I've asked for a whiteboard. If someone needs something different, please contact David Cripe. Have Fun! Reg

In the CCW articles I recall by Wes Hayward, (but can't find #$%$) CCW was described as integrating over dit frames and comparing the sums. However, I recall no mention of how much of a difference in level constituted a signal. That was where I started a month or so ago at implementing CCW and QRSS. The problem was I had no way to calculate expected results ready to hand. So I stepped back and thought about the concept, "the power level in this dit frame is different from this other dit frame" and how best to measure that in real time at minimum cost. That led me back to basic physics, probability theory and statistics. Because of my seismic background my first inclination is to slap things around with some transforms. But that is not MCU friendly. Computing the mean and standard deviation for a dit frame is very low cost and very easy to implement in a DSP setting on an MCU. Computational cost is one multiply and 2 sums per frame sample plus 3 multiplications, a sum and square root per dit frame. Then make a decision based on measured statistics of the QRN whether to emit an audio tone or not. It introduces a single dit frame latency. The output is either a pure side tone signal or silence. No hiss. In the absence of a signal, we expect the QRN to be a Gaussian random process in the BW of the channel. More particularly, we have an expectation of both the mean and the variance. By initializing the receiver for 10 seconds on frequency to record actual QRN and determine the mean and standard deviation we now have a statistical criterion by which to eliminate QRN. By setting a threshold value for the mean value at a specified standard deviation we can distinguish if a very low amplitude signal is present in addition to the noise. As the Gaussian is well tabulated one can set the threshold for any desired level of spurious noise as a BER in percentage probability. The clock frame timing is the key to making it work. If the receiving dit frame is off by 50% there will be no change. Hence the need for synchronization. That will be a separate topic. The standard deviation of the dit frame comes in to play in the presence of QRM. By tracking the variance of the variance, one can subject noisy dit frames to a different criterion based on the variance. If only a constant sinusoidal signal is present, the change in variance will be small. If a dit frame has a noise burst present, the increase in the variance can be used to select a different threshold level or other processing. An effective QRM filter for rejecting periodic noise bursts could be developed on top of the basic clocked frame by developing another layer for burst noise based on the variance of the dit frame estimates of the mean and standard deviation among frames. Have Fun! Reg