Disproving the Conjugate Match Claim

Discussion in 'Amateur Radio' started by W5HRO, Apr 9, 2015.

  1. W5HRO

    W5HRO Administrator

    Dave, G3UUR sent me his last write-up on the Conjugate Match debate today where he was finally able to disprove that claim. Attached below is the last full unedited document. An older slimmed down version appeared in AntenneX magazine a few years back.

    This became a very hot and often heated topic on the ham boards and peaked around 2011. Dave then got busy with other stuff and has been absent for the past few years. The below was copied and pasted from the last part of his attached pdf document and a few of the symbols may not have transferred so refer to the document for anything that might be missing.

    Dave Gordon-Smith, G3UUR: New Method of Measuring ROS ……… 27th July 2011


    The measurement of amplifier output resistance described in this article shows conclusively that there is a loss mechanism associated with tube operation that is referred to the output of any power amplifier as a dissipative resistance. This demonstrates quite clearly that ROS is not a non-dissipative resistance as W2DU and VE2CV have inferred from their limited evidence, because such a resistance would not broaden the bandwidth of any network following the amplifier. In addition, the magnitude of ROS is substantially less than the load resistance, RLOAD, even when the amplifier is tuned for maximum output according to the reverse SWR (RPG) method. This is because the tube source resistance, RDS, and optimum load, RL, are governed by two totally different tube parameters. In this respect a tube power amplifier is quite different to an idealised Thevenin source, and trying to interpret experimental results using a model based on the latter will always lead to erroneous conclusions. The RPG experiments conducted by W8JI [5] and the load-variation measurements made by W2DU [2] are only capable of detecting the time-averaged value of the dynamic plate resistance, rp. It is this parameter that determines the optimum value of load for maximum power transfer and the resistance that terminates the input of the tank circuit for any probe signal being fed back into the amplifier during a reverse SWR test. Plate resistance is just the name given to the mathematical ratio Ep/Ip with Eg constant. It’s a measure of how much varying the plate voltage influences the plate current. It affects the way the power delivered to the load changes as the load line is altered and behaves just like RS in a Thevenin source in this respect, causing a peak in output power and an ‘apparent’ conjugate match. However, it’s not a real resistance and does not dissipate any power when the tube conducts because none of the plate current due to grid drive goes through it. So, it cannot provide the input termination for any selective network or antenna following the amplifier. Only dissipative resistance can do that.

    Doug Smith, KF6DX, has already pointed out [6] the inconsistency between the results of RPG measurements and the claim that the source resistance is nondissipating, but to date no credible explanation has been given by the pro-CM lobby to resolve this difficulty. In reality, of course, the probe signal in an RPG experiment sees the plate-cathode resistance disguised as rp for the time the tube conducts because it only varies the plate voltage. This terminates the input of the pi-network tank circuit for any reverse signal and presents it with a radically different value to the loss resistance experienced by the plate current driving the tank circuit. The probe signal alters the plate current asynchronously by a small amount and is dissipated at the plate along with the power that’s lost from the flow of plate current that’s going into the tank circuit. Plate resistance is the only characteristic of a tube that can be non-dissipating in the forward direction and appear to be dissipating in the reverse. No other characteristic of the tube or matching circuit can behave in this way. The total dissipative resistance experienced by the plate current is governed by the sum of all the instantaneous power lost across the tube during the time it’s conducting. Part of this lost power is associated with wave shaping (RWS) and part of it with the output resistance (RDS). The latter is determined by epmin/ipmax and therefore related to the drive level and the proportion of the DC supply voltage used by the plate swing. This has been confirmed by tests on linear amplifiers where the drive and plate swing could be varied. So, other properties of the tube, and not rp, determine the level of efficiency and the dissipative output resistance. The whole operation of a tube HFTPA is not just subtly different to a Thevenin equivalent source; it’s radically different to it because all 3 properties associated with RS in a Thevenin source are governed by different characteristics of the tube in a power amplifier. Therefore, the Maximum Power-Transfer Theorem, which is based on a derivation involving a Thevenin equivalent source, cannot be applied to power generators using active devices. However, the conjugate match is still a useful concept when considering matching problems and does apply to other power sources such as receiving antennas, so should not be dismissed as a theoretical irrelevance and ignored.

    It’s worth noting that the peak in output observed during RPG and loadvariation tests on AB1 amplifiers occurs at power levels higher than those recommended for linear operation. This is because the value of Rp, and hence rp, in real tubes varies across the plate characteristics, and is normally too high to meet the optimum-load condition at moderate and high plate voltages, though load-variation measurements still show an apparent source impedance of 60 to 80 under these conditions because of the diluting and obscuring effect of the pi-network transformation. For load-variation figures closer to 50, the end of the load line has to be pushed further down into the non-linear, low-voltage, high-current region of the plate characteristics by increasing the value of the load presented to the tube by the pinetwork matching circuit. Then, rp can be forced to drop significantly so the optimum-load condition can be met by some lower effective value averaged over the plate swing. It is only in this condition that the reverse SWR method provides a perfect match well over the recommended output for tube linear amplifiers. Perhaps Warren Bruene [4] had it right when he said “maximum power output is clearly determined by non-linear tube conditions.”

    New results presented by W2DU [1] in Sec 19A.5 actually support the idea that the peak in power at maximum output occurs because of the interaction between the load and the tube plate resistance, rp. Walt doesn’t agree, of course. However, his interpretation of these results ignores the fact they show quite clearly that the tank circuit is transparent to steady-state changes and he has an ‘apparent’ conjugate match right at the plate where he’s making the measurements. By suggesting that the Q somehow isolates the input of the tank circuit from the output, he’s blatantly ignoring the fact that he can measure this ‘apparent’ conjugate match right at input of the tank circuit. How there can be any isolation at all if he can do that is very hard to believe! He’s also breaking the golden rule of transmission-line theory, which is that if a conjugate match occurs anywhere in a system it occurs everywhere, including right back to the source – this should be mentioned somewhere in one of the earlier chapters of his book. His claim also ignores a basic tenet of circuit theory that the dissipative resistance presented to the input of a network is always referred through to the output in some form, or other, depending on its relationship to the characteristic impedance and the phase delay of the network, regardless of any energy storage along the way. Various types of filter with Q values far in excess of the tank circuit in an HFTPA refer the dissipative parts of their input and output terminating impedances through to the other port. This is a well established fact and tank circuits with only modest values of Q are no exception. If rp was a dissipative resistance rather than a mathematical ratio, there would be a conjugate match at the plate, but it doesn’t and there isn’t.

    Correcting Misconceptions

    After the publication of W8JI’s RPG test results [5] in 1997, there seems to have been a gradual acceptance amongst radio amateurs that a conjugate match exists in RF power amplifiers and the myth has become well established now. However, this widespread acceptance appears to have come with little recognition that it requires the output impedance to be partially non-dissipating to explain the more than 50% efficiency obtained with most tube RF power amplifiers. Some amateurs now routinely assume that the broadening effect of the output impedance makes the bandwidth twice what it would be for the load alone, whether it does or not!

    It seems more attention should have been paid to the pertinent points made by Warren Bruene [7] in a letter written to the editor of QEX back in 2005. He pointed out that a tube is basically a voltage generator, despite the fact that the plate current is grid-voltage controlled, with such a low value of output resistance that it’s possible to create an impedance inversion and get a current generator with a high value of source resistance if the tank circuit and transmission line together provide an odd number of 90º phase delays. Apparently, this is a trick discovered by broadcast engineers to increase the field-strength response of high-Q antennas to improve the transmitted bandwidth. So, in practice, the broadening effect of the dissipative output resistance of a power amplifier can be anything from the minimal influence of a voltage generator with low dissipative output resistance to the considerable widening effect of a current generator, depending on the phase delay of the matching network and the length of the transmission line. This would not be the case if a conjugate match were a reality in RF amplifiers because a line with very low loss would be matched fairly well looking down it in either direction at every point along it, no matter what its length, and no variation of the effective source impedance would be evident. The conjugate match in HF tuned power amplifiers is not only elusive, it’s an illusion!


    1 M. Walter Maxwell, W2DU, Chapter 19A in “Reflections III: Transmission lines and Antennas,” published by CQ Communications Inc., April 2010, ISBN: 0943016436.

    2 Walter Maxwell, W2DU,”On the Nature of the Source of Power in Class-B and –C Amplifiers,” QEX, May/June 2001, pp32 - 44.

    3 Robert Craiglow, “RF Power Amplifier Output Impedance Revisited, QEX, Jan/Feb 2005, pp 29-37.

    4 Warren Bruene, W5OLY, “The Elusive Conjugate Match,” Communications Quarterly, Spring 1998, pp 23-31.

    5 Jack Belrose, VE2CV, Walter Maxwell, W2DU, and Tom Rauch, W8JI, “Source Impedance of HF Tuned Power Amplifiers and the Conjugate Match, “Communications Quarterly, Fall 1997, pp25 - 40.

    6 Douglas Smith, KF6DX, “Letters to the Editor,” QEX, May/June 2006, p61.

    7 Warren Bruene, W5OLY,”Letters to the Editor,” QEX, Mar/Apr. 2005, p62.

    Attached Files:

  2. W3SLK

    W3SLK Member

    Hmmmm. I can't seem to find the treatise in Walter Maxwell's book that he refers to. I do have the latest and last revision of it. He signed and sent it to me about 2 months before his passing.
  3. W5HRO

    W5HRO Administrator

    Which book, article or joint article? I didn't even know Walt had died. Shows you how much I've paid attention in the last few years. Maybe that's one of the reasons why the activity on the other AM board has dwindled down so much. Too many of those guys have died off recently.
  4. W3SLK

    W3SLK Member

    Reflections III. I got it in January 2013 and I think Walt passed away in April. I'll have to check the archives on the other board though. I can't find Chapter19A that he refers to. I found Chapter 19 without any problems though.
  5. W5HRO

    W5HRO Administrator

    Maybe it was in an older revision and Walt and/or CQ deleted it after Dave's article was published in AntenneX? Could also be a typo maybe, but...
  6. W5HRO

    W5HRO Administrator

    By the way this kinda of reminds me of the other topic I started regarding the New Challenge to the Big Bang Theroy

    It's the same thing as when Dave says towards the end of his article "After the publication of W8JI’s RPG test results [5] in 1997, there seems to have been a gradual acceptance amongst radio amateurs that a conjugate match exists in RF power amplifiers and the myth has become well established now." Well, ever since Stephen Hawking came up with his theory it's been well established and today we even have a TV show called the Big Bang Theroy. The theory is pretty much accepted as being correct and the norm today. Well, that doesn't mean the theory was and is correct and if someone comes up with a new theory and can prove it with calculations and evidence showing that Hawking's was wrong then it should be considered, right?

    Unfortunately our society doesn't seem to work that way and when 99% of the world has been led to believe something is a given when in reality it isn't then it can be very difficult to wake that world up and make it see and understand it's mistake. Just because two or three hams who had limited abilities and resources published one or two articles and/or books starting around 18 years ago doesn't mean they were right.
  7. G3UUR

    G3UUR Member

    It was certainly Walt's intention to include Chapter 19A in "Reflections III" according to what he told me in an exchange of emails we had prior to its publication. I don't have a copy of his book, so I don't know for sure whether it was included or not.

    Searching the Internet for references to it brought up a number of hits, so others appear to know about the contents of Chapter 19A. I know it was on his website - www.w2du.com - for some while, but that website has now disappeared.

    I'll check on my old PC to see if I kept a copy of it.
  8. W5HRO

    W5HRO Administrator

    I did a Goggle search and typed in "Reflections III Chapter 19A" and found it. It was in a Goggle Groups forum. Clicking on that link went to http://www.w5dxp.com/Chapt19a.doc and it's also attached below. Hopefully it hasn't been edited by anyone, but Dave is right. Many knew about it because there were actually responses to it via some of the other links.

    P.S. I also remember Walt posting Word documents like this one on the other AM board because CQ was having a problem when they tried to open them with their word processor. A lot of the symbols in the equations were not being transferred and appearing and he was asking for help. It's possible this was the one or one of them, but I don't remember. Maybe that thread is still there because I do remember posting in it.

    Attached Files:

  9. W5HRO

    W5HRO Administrator

    Attached below is what Walt emailed Dave years back. It should be the same as the one I found via that link and I'm posting it just in case.

    Attached Files:

  10. WD5JKO

    WD5JKO Member

    Good to see Dave back here. Last time it was about the Retro-75 AM transceiver.

    A bit off topic, but I recall years ago doing a video sequencer to get 4 pictures on one monitor. This was >25 years ago, and the CCTV was B&W. I used FET switches to sequence through the individual cameras. Then I needed a good video driver to drive a long coax run. I tried several things, and using a low Rs driver always worked the best. Adding a series 75 ohm dissipating resistor seemed to lower the CRT contrast, even if I adjusted the level upstream of that 75 ohm resistor to compensate for 6 db of loss when feeding a 75 ohm load.

    I went back and found my notes on that project. I was using +/-12V supplies feeding a 2n7000 as a source follower which also wiggled the common pin of a 78L05. The regulator input went to + 12V, and the (5v) video output went to -12V through a resistor. I measured the Rs of the setup, and at 1 Khz it was 2 ohms, and at 5.4 Mhz it had risen to 10 ohms. Imagine a 78L05 passing video! :icon_wtf:

  11. W3SLK

    W3SLK Member

    He may already of had this incorporated into Chapter 19. I'm going to be straight up here fellows, the mathematics behind the conjugated match is not my forte'. As a matter of fact, I was talking, (chatting with him via email) Walt about this and was in the process of reading. I was prepared to purchase the book outright but he sent it to me free of charge with a nice note attached. This was soon after Carl, K1KH, verbally abused him on the AMphone board and was subsequently given the boot. I wanted to learn more about the discussion so he sent me the 3rd edition. I think it was a month or 2 after he sent it to me, I left the board, (because they excommunicated Bruce, W1UJR, for whatever reason). I returned to ask Walt some more questions and learned of his passing. So now I will attempt to learn this stuff on my own and try to decipher it. I'm too afraid of taking it to work with me for fear of falling asleep during night shift.
  12. G3UUR

    G3UUR Member

    I tried to keep the maths as simple as possible in the description of my method of measuring Ros and used a graphical method of illustrating why a peak in output is produced by the plate resistance interacting with the load. I know some people don't like maths at all, but there was nothing I could do to simplifiy it any further.

    I'm surprised to hear Bruce, W1UJR, has been banned from the other AM forum. I'm not sure whether I have or not, but certainly a post I put on there on behalf of Gary, ZL1AN, was removed immediately. Gary wrote to me complaining that information from his website had been used by someone in the CM argument on AM Fone without his knowledge. Since Walt had heavily criticized it, he felt he should have been given the chance to defend it. Apparently he'd tried contacting Walt but got no response, so he tried me. I pointed out that the offending individual who'd used his information was one of the regulars on AM Fone and offered to post something on that site pointing out the responsibilities those who use information from other websites have to the owners of those sites. That got squashed immediately, presumably just because I dared to mention the CM debate. I haven't tried to post anything since.

    Hi Jim! One of the great delights in this heavily integrated world is to find different uses for specialist ICs. You can get lot of satisfaction from doing that. Your mention of the Retro-75 reminds me that I've got to find some time to build a little AM rig for 60m. That's a very useful band for inter-G during the daylight hours and there are some very interesting contacts going on there.
  13. W5HRO

    W5HRO Administrator

    Bruce, W1UJR had one of the first AM websites called AM Buffalo along with AM Forever and AM North America when we all first started them. That was back in the mid 1990's. I spoke with Bruce on the phone a few times back then because I had created an AM webring and we were trying to link our sites together with it. Bry, AF4K had started the very first one called the Boatanchors webring.

    Anyway, and this is just a guess, but I think Bruce and Gary may have been friends and when AMfone's ownership change hands back around 2011 they forced him out. I remember Bruce created an account with AM Forever right after his profile was changed to "Guest" but he never logged on again so I'm not sure what happened for certain. Brian, W5AMI who started AM North America was always a real jerk (at least to me he was) but in the very early days when they first started the forum, it was pretty cool and then Brian stepped down and Gary took it over. It then became AMfone. It didn't start getting bad until some of the other member's became moderators and it slowly turned into the regional northern east coast paranoia thing you have today. Sensitivity in the workplace type of thing and always having to be politically correct, etc. That's the reason I re-branded this board using the old AM North America name to try and bring everything back like it was in the very beginning.

    It's unfortunate because there are a couple of decent guys on there like Steve, WA1QIX who have been holding down the technical side of the fort recently. Steve is a really nice guy and he and his wife stopped by my house one night on the way back from Monterrey and Carmel. They have a son who lives up in Berkeley. Steve hasn't been back to this board again in a long while now and I have a hunch some of his AM buddies there probably gave him a hard time about meeting me and this board and probably teased him. Anyway, that's my guess but who knows for certain. Just thinking out loud.

    Oh, and we also had one member of AM Forever located in the Dallas Forth Worth area who contributed a lot, but at the same time liked to try and disrupt the board with intentional hacking. The old phpBB3 software turned out to be a real resource hog with the shared server and it was always causing problems with it. It didn't help matters any when that member was constantly trying to make things even worse. After analyzing all of the core dumps which recorded the ip addresses myself and the hosting company were able to determine that it was him.

    Getting back to the CM debate, I think it was all of the other members who really didn't have any real technical knowledge about the subject constantly jumping in and making rude comments. If Dave, Walt, and etc. could have been left to discuss it in peace without all of those other nonsense posts then it may have turned out much differently. Unfortunately we will never know that now.
  14. G3UUR

    G3UUR Member

    The old W5AMI website is a familiar one to me. I remember discussing Class E with Steve at some time in the dim and distant past on one of those forums; it might well have been that one. I also remember Brian, AF4K, having a site where lots of Brits were reminiscing about their days in the CCF. I didn't join in because I was in the Boy Scouts and the Air Training Corps and had no interest in army radio sets back then. Anyway, thanks for explaining a bit about the history of these websites, Brian. I wasn't aware of how they developed and changed hands, other than the present lot taking over AMfone from Gary.

    You're absolutely right about the CM discussion on AMfone, Brian. There were far to many pointless, crass interruptions that got in the way of a serious discussion. They certainly allowed Walt to avoid answering some of the more difficult questions I put to him. It's a shame we weren't able to carry on as I really wanted to question him about his claim that the NASA 400-cycle alternator was a good example of a matched generator that had more than 50% efficiency. Tom Rauch, W8JI, also brought up this alternator as an example to back up his argument for CM in HF amplifiers in a later argument I had with him on either qrz.com or eham - I can't remember which now without refering back. I'm baffled as to why either of them could believe that any AC machine like this could ever possibly provide a conjugate match to the load when the source impedance is predominantly inductive and the load has to be mainly resistive to get the efficiency. An AC machine specialist may refer to this as a matched condition, but it's sure as hell not a conjugate match.
  15. W5HRO

    W5HRO Administrator

    Gary started the AM Classifieds which is what turned into the AMfone forum. They basically merged AM North America and the AM Classifieds together then changed the name to AMfone shortly afterwards. There were a few of us who also had AM websites at the time, but it was primarily mine and Bruce's. AM Forever and AM Bufflalo I think. Forget the AM Window :icon_yawn:

    Bry, AF4K also had like a billion webpages all over the internet about various things like the one you referred to. There were a lot of free webpage hosting places back then and I think he utilized almost all of them. Some of those still remain today, but the content doesn't always display properly using today's modern browsers.

    Anyway, hence the theme here of AM North America; Tons of vintage material with a forum and a new classifieds add-on.

    Yeah, the CM debate got pretty heated at times. To be honest though I doubt if Walt would have answered all of the questions even without the crass interruptions. When you put someone on the spot in a public forum where the whole world is watching then they may tend to clam up and never respond anyway.
  16. W3SLK

    W3SLK Member

    Brian said:
    I disagree with you there, Brian. I am not going to say I knew Walt inside and out, but he seemed to be a commensurate professional. Like anyone else, he would fight back any contradiction to his theories until he would see the error himself. Then, I think he would admit the error in his ways. Unfortunately, we will never know for sure.

    Talking about the old board, there seemed to be something about Bruce and his acquiring a KW1. One of the other board zealots felt he wasn't deserving of it and banned him at every turn. I have found Bruce to be nothing short of a gentleman and chat with him regularly on Facebook. Brian W5AMI, still posts every once in a while on the AM reflector. I never had any problems with him. Bry, AF4K, has his hands everywhere. He still selling stuff. I find him to be a good business man and one to be trusted. The only one I can't stomach is Pete WA2CWA, and his ARRgghhL ways.
    I have know Steve Ickes for a good number of years. The fact that he got ostracized for talking to you shows the group has grown beyond it's pants!!!
  17. W5HRO

    W5HRO Administrator

    That's the dumbest thing I have ever heard! If true then what kind of a moron would be jealous enough to ban a user for having a KW1? A KW1 is no big deal anyway. Not sure if I believe that or not.

    Wrong Steve...
  18. W3SLK

    W3SLK Member

    Sorry, my bad. I get those dyslexic moments every once in a while. The result is still the same. To be browbeaten because they stopped by to visit a fellow AMer is beyond pale. Its funny Brian, I never known you to post anything derogatory or hateful on that board. I was a regular and checked in numerous times a day, sometimes just to 'read the mail'. I'm glad you started this one. :biggrin:
    The thing with Bruce started when Todd, KA1KAQ, became a board moderator. It was over some Collins gear and I am pretty sure it had to do with a KW1. I used to like Todd, but when I watched that transpire, I took a note out of Rich Measures book and voted with my feet.
  19. W5HRO

    W5HRO Administrator

    It's funny because in my last post I almost said "If true then what kind of a moron toad would be jealous enough to ban a user for having a KW1? That individual did pop into my head. That's the kind of mentality and thing a CB operator would do when someone has a bigger linear than they do ::) The way I see it though if true then it's the site or board owner's fault for letting that kind of thing happen in the first place so who's fault is it really?

    Oh, as for Brian, W5AMI he a Gary Gompf, W7FG got together and Brian posted an article about me on the old AM North America back around 1996 or 1997. It was all because Brian was still learning and wanted to build an antenna tuner and we were discussing it on 3880 one morning. I told him to try a simple pi-network tuner and see what happens, because the typical T-network tuners are high pass and you really want a low pass instead. At the time I didn't realize he was going try to and use it on an old boatanchor transmitter which already had a pi-network. I thought it was going to be used to tune a fixed 50-ohm output source to a 50-ohm or whatever antenna. A pi-network can be made to work fine with that and with super high Q if you pick the right values. If I'd known what he was going to use it for I would have told him to just build an L-network tuner to make the whole setup a pi-L network. So when Brian tied to use the pi-network of course it didn't work because of the extra Vcap in the mix and the values he used. Gary wrote an article making fun of me about it and Brian posted it on AM North America and that's what started it all.

    What Brian didn't know was that Gary, W7FG was a little bitter towards me at the time. Gary worked for Phillips in Bartlesville Oklahoma and at one time was part of a division that had an RF telemetry data acquisition system used to locate oil. The system produced 3D maps. Phillips sold that division to two of the employees who wanted to keep it going and they moved everything down to Tulsa. Well, they didn't like Gary because of the way he was so they forced him out. The person who replaced him when they moved everything to Tulsa was me. It was funny because I went to Gary's house on multiple occasions because we often traded vintage equipment and parts. Then during the last visit I asked him about what had happened with him and the old company and he was shocked to find out that I knew them and that I had his old job. He got really mad when I brought up their names and that was the last time I ever saw him. After that day occurred things changed and he started becoming a real jerk towards me both on and off the air and when he got Brian involved Brian became a real jerk from that point on as well.

    Anyway, I think we have digressed away from the Conjugate Match topic long enough and as far as Walt was concerned what I should have probably said was that I doubt he could have answered all of Dave's questions simply because he would not have been able to. Not trying to put Walt down or anything because he was a smart guy and contributed a lot to the amateur service and community, but I think at times he just got in a little over his head on certain subjects.
  20. K4TQF

    K4TQF Member

    Ok, I think my head is about to explode ! I have been reading about antennas, grounds & transmission lines, tuners, etc... all winter in preparation for my move to the new QTH. Then, the other day, I opened the old standby "Radio Handbook" 19th ed, 1972, edited by Bill Orr, and read this in sec 25.20 Antennas & antenna matching: Standing waves; "As was discussed earlier, standing waves on the antenna transmission line, in the transmitting case, are a result of reflections from the point where the feed line joins the antenna system. The magnitude of the (SWR) is determined by the degree of mis-match between the characteristic impedance of the transmission line and the input impedance of the antenna system.... "( so far so good) "... It may be well to repeat at this time that there is no adjustment which can be made at the transmitter end of the feed line which will change the magnitude of the standing waves on the transmission line."

    Wait a minute... I was under the impression that the tuner did just that when it brought the whole system into resonance. :icon_wtf:
  21. K4TQF

    K4TQF Member

    Life and ham radio seemed so much simpler 50 years ago ! We didn't need no stinking velocity factors or conjugate matches ! Dig in the junk box... find a 6L6 and a xtal, wire it up and tune for minimum chirp ! ( or build a fancy regulated power supply) Or, better yet... get a mil surplus rig that would load a wet noodle... and run it off a couple of car batteries in series.

    My neighbor, the old retired telegrapher and former "sparky" for United Fruit in WW1, had a BC-348 & a little novice transmitter of some sort. His antenna was 100% zip cord (18ga lamp cord) It came out of the rig to a knife switch for transmit-receive, ran up beside his hot water tank vent pipe (metal) into the attic. From there, it split and went to one end of the attic and hung down the side of his house. The other end turned a right angle and went out the attic window and was tied to a fence post in the backyard ( literally, tied in a knot) :icon_crazy:. I don't know his stats, but his wall was covered with QSL cards. One, I remember in particular, was from New Zeland. Ah, the "good old days".
  22. W5HRO

    W5HRO Administrator

    That really isn't the exact same thing as the CM debate, but it does apply. The CM debate focused primarily on HF tuned power amplifier networks and the overall network does include the load (antenna) and the transmission line.

    During the CM debate argument Walt refused to back down and I found the two attachments below on the other board. Even the ARRL pulled the plug on him regarding the issue because they were chasing a myth that didn't really exist. Walt was not very happy about it and thus the reason for his response within the first attachment.

    Also, the part below on page 20 of the first attachment confirms Dave's comment about the existence of Chapter 19A. The big question is did that chapter get included in his Reflections III book or did the publisher pull the plug on it just like the ARRL did? I've already attached chapter 19A in one of the previous posts.

    "In closing, let me say that Chapter 19 in Reflections 2 explains in great detail why Bruene’s claim that a conjugate match cannot exist when the source of power is an RF power amplifier is wrong, proven with data resulting from measurements presented there. In addition, measurements performed since Reflections 2 was published yielded data that even further proves Bruene’s claim is wrong. As stated above, this additional data appears in Chapter 19A of the forthcoming third edition of Reflections. Both Chapters 19 and 19A are available for downloading from my web page at www.w2du.com. If you still believe that Bruene and Straw are correct in their position concerning the conjugate match, I urge you to review Chapters 19 and 19A (or Chapter 19 in Reflections 3) at your earliest convenience. I’m confident that reviewing them will challenge your thinking."

    Attached Files:

  23. K4TQF

    K4TQF Member

    Dave states on the front end: "... It measures only dissipative resistance and the results show quite conclusively that not only is the real part of the output impedance dissipative, but it is also substantially less than the value of the load when adjusted for maximum power." makes perfect sense to me... and I don't know nutt'in.

    I wonder why the others didn't see that from the git-go ? It seems to me that the output tube is where one would go from Ohm's law to Kirchoff's law... i.e. the tube has certain DC characteristics but it is generating or amplifying an AC signal.

    A sticky wicket in any case.
  24. W5HRO

    W5HRO Administrator

    A sticky no balls AMfone wicket :lol:

    In all fairness to Walt though many think he was being protected by the guys on the other board which is only partially true. The biggest part of it was one of the moderators was closely connected to the ARRL and still is and he and some of the others were protecting themselves. They didn't really want Walt on there discussing the CM debate with anyone so whenever things became heated they started shutting it down at every turn. If they would have just had the balls to let it go and let the chips fall where they would have fallen then it all would have ended anyway. Walt was definitely in a little over his head on the CM debate and he was protected by those who were really protecting themselves.

    By the way, remember in the other topic where I brought up making the 1:1 balun or line isolator using ferrite beads slipped over a 1 ft piece of coax in a piece of PVC pipe with end caps instead of using the coax choke type balun? One of Walt's biggest contributions was coming up with that concept and balun using the ferrite beads. He got the idea from a spacecraft antenna designed by RCA's Astro-Electronic Division. Anyway, they actually started making those WD2U series Unadilla baluns decades ago, but they were sort of cheaply made and didn't hold up very well to weather and the higher AM carrier power levels, but that's when the whole thing started and where those baluns and/or line isolators originated from for use in the amateur radio service.
  25. K4TQF

    K4TQF Member

    Yes, and that's a good suggestion.
    I have Walt's "Reflectons" printed & bound. I also read his rebuttal. It's seem to me that he just didn't have the info or like you said, he was in over his head. Old beliefs die hard... I also had Sevick's book on Baluns printed & bound. I'm certainly no engineer, but I can read and understand ( for the most part ) what I'm reading.

    My criteria are simple... If I'm making contacts, nothing is smoking, & the XYL isn't getting RF burns from the kitchen faucet, no complaints from the neighbors about TVI, then I'm OK ! :icon_thumbup:
    BTW: The first piece of test equipment I bought, when I was 12 years old, was a field strength meter. I was just having fun with it measuring field strengths from broadcasters in my hometown. As it turns out, the proof is in the pudding.

    I'm also getting into these..."Old Wives Tales" by W5DXP http://www.w5dxp.com/OWT1.htm