My First-Ever QSO -- 50 Years After Passing Ham Test

Discussion in 'Ham Radio Discussions' started by G3EDM, Aug 27, 2021.

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  1. G3EDM

    G3EDM Ham Member QRZ Page

    This superb vintage Simpson 260 arrived today. It is in excellent shape, but of course "the proof is in the pudding" when buying old test equipment. I've always wanted a Simpson, and this is actually my first decent VOM. (I also have a VTVM, which is in storage.)

    I jumped on this particular item because second-hand Simpsons don't come up for sale in the UK that often, or when they do, there are doubts about the condition. British hams and electronic technicians would often, in the past, use the famous AVO-meter rather than the American Simpsons or Tripletts.

    The price IMO was very reasonable, but that's in the eye of the beholder. It cost a lot less than a brand-new Simpson 260 (they are still made!).


    73 de Martin, G3EDM
    Last edited: Sep 14, 2021
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  2. G3EDM

    G3EDM Ham Member QRZ Page

    My vague recollection is that the idea was to put the RF stage there, not for gain, but for helping to attenuate strong signals when needed. Hence, making it tunable. At the bottom end of its range, the RF gain control cuts out the signal altogether. But as you said earlier, that may not be ideal given the tube characteristics at low gain.

    My approach when experimenting in this wild manner is often to "build it again, but differently and better" rather than altering an existing set. You've seen what a rat's nest I made. But it is modular: so you can yank out a particular stage, build a completely new one along different design lines, and then slot it back into the circuit.

    At least when I was doing a lot of this six years ago, subminiature tubes were cheap, you could buy fairly large quantities for not much money. Cheap enough that if you "smoke" one of them (and this happened several times!) it is not a big concern. I also used modern, cheap resistors and capacitors. The only "precious" items are the vintage variable capacitors and, in this case, Amphenol coil forms. I used those forms because my intention initially was to "finish" this set properly, by building an identical duplicate one in a proper cabinet, much smaller, and with a clean layout. The Amphenols (re-wound neatly, fixed with coil dope, and without the Scotch tape!) would form part of a set of plug-in coils for each band. (I've been hoarding Amphenols for years.)

    I am not averse to experimenting, even now, six years later, with this design. But that would probably be as part of a progression toward building a "proper" desktop iteration of it, and it may not involve altering the existing rat's nest.

    Among other things, subminiature tubes are very well suited to PCB construction. Also, they really don't need much ventilation, or any ventilation at all. I don't know where one can find software to design PCB layouts for circuits of this type, but I personally would be thrilled to do something like that. Also, apart from the critical area around the detector (where spacing of the elements is crucial), such a set could be made quite small. My shack is tiny....

    Another issue is the PSU. I actually rather like using batteries, partly because it eliminates any possible issue with AC hum. But it is a pain to remove them for recharging, and in time, the holders will wear out. So one possibility would be to build a recharger that would supply (for instance) 52VDC for the B+ battery set so they could all be recharged in situ, rather than having to be removed for recharging. OTOH substituting an AC driven power supply and eliminating the batteries would, admittedly, save a lot of space!!!! (Also, modern rechargers have "clever" circuits for properly charging the batteries, perhaps better not to try building my own recharger.)

    Finally, it could be argued that time spent now, tinkering with this regenerative design, would be better employed building my first superhet and/or building that converter for my BC-453. So much to do....

    73 de Martin, G3EDM
    Last edited: Sep 14, 2021
  3. SM0AOM

    SM0AOM Ham Member QRZ Page

    The Simpson 260 were the "staples" at a previous employer.
    Each and every technician had one.
    As the earlier models were unprotected, they sometimes got a "messy" end.

    There were definite "difference of tastes" between users,
    the Army "swore by" the Austrian made Metrawatt series, which were very robust
    and versatile, the Navy used the AVO 8 and 9, and the Air Force the German Siemens multimeters.

    The Telecom Administration used Simpsons, and the Universities Metrawatt or Gossen multimeters in their labs. Japanese multimeters from Sanwa and TMK were sometimes used for less demanding applications, but were viewed with suspicion.

    A somewhat special case were the multimeters issued with the leased ship radio stations.
    Here, the AVO Multiminor was used, as they were viewed as "expendable". The R/O was considered certain to blow them up, so it was chosen from a replacement price perspective.

    My own tastes are somewhat "slanted" against the HP and Marconi measuring gear.

    On the shelves above the test bench there are two HP427A battery-powered multimeters, an HP412A VTVM, a Marconi TF2604 mains-powered VTVM, a Wavetek true RMS DVM together with a Goerz Unigor A43 analogue VOM.

    The Unigor family was still produced only a few years ago, and to my shock I recently realized that the A43 with its leather protective pouch cost almost the equivalent of £1000.

    Three years ago, my workplace downsized its office space, and the "museum showcase" of "ancient" instruments had to go. I was offered my pick of its contents, and went away with
    an AVO 7 in its literally "bullet-proof" metal case, a Rohde&Schwarz audio level meter, a Siemens
    telephone transmission test set ("Pegelkoffer") and a Boonton 190 VHF Q-meter.

    Had this opportunity not been offered, I am quite convinced that the "bean-counters" had thrown them all on the scrap heap, using the usual excuses; "nobody understands how to use analogue test gear anymore..."

    W9BRD and G3EDM like this.
  4. G3EDM

    G3EDM Ham Member QRZ Page

    My QSO count may well dip sharply for the next few weeks, despite now having a much better receiver.

    But there's nothing to worry about, it's because of a set of short-term factors:
    • Life In General. I've been spending too much time on the hobby and not enough on things that really need to get done, professionally and otherwise.
    • Most of my useful crystals have been temporarily retired since two days ago when I finally got the technical capability to monitor my own signal. They were discovered to cause significant yoop, chirp, or drift. I was actually able to conclude quite a lot of QSOs with these "bad" crystals but having now heard what they sound like, I cannot in good conscience go on inflicting them on my contacts.
    • With so few usable crystals in the CW band segment, and given that I operate entirely by calling CQ and waiting for answers, it has now become hard or impossible to frequency-hop to avoid QRM and find a nice clear frequency to park on and be clearly heard. This already seems to be reducing my QSO count.
    • Some, or perhaps almost all, of the issues with the "bad" crystals are caused by well-known issues with the "Boosted Pierce" oscillator in my transmitter putting too much stress on the crystals. The transmitter can be altered to alleviate, or maybe even eliminate, these issues. But this will take time; I hesitate even to estimate how long, hopefully a matter of days or weeks, not longer. I've started procuring the components for this. It is a case of: Try A, test; if not solved, Try B .... There are a half-dozen "fixes" in ascending order of difficulty/complexity.
    • The fallback solution if transmitter improvements are not sufficient to solve the problem is to restock my crystal collection with "known vintage" FT-243 crystals, which are usually able to take the punishment inflicted by the Boosted Pierce. This is a relatively slow and expensive option but if it comes to it, that's what I'll do. My few "good" vintage FT-243 crystals sound EXCELLENT on-air.
    73 de Martin, KB1WSY
  5. G3EDM

    G3EDM Ham Member QRZ Page

    Mine does say OVERLOAD-PROTECTED on the meter fascia. At one point it might be worth tracking down the serial number to find out how old it is.

    Not sure how the protection works, does it just blow a fuse or is there some other element involved?

    73 de Martin, G3EDM
  6. G3EDM

    G3EDM Ham Member QRZ Page

    @SM0AOM: I love old analogue test equipment, but have a slightly different "take". Unlike an EE who needs rigorously precise, and rugged, test equipment in their professional lives, I tried to re-create the panoply that a homebrewing ham in America might have had in the 1950s, if s/he was keeping to a modest budget. I ended up focusing on test gear made by Eico, which was known for its moderate prices and not particularly good gear; but it got the job done.

    Here is some of what I had in America, and still have here in England but in storage:


    Most of the test gear has been carefully restored by me, including recapping and serious cosmetic work. Selenium rectifiers were replaced with silicon.

    My Eico grid-dip meter:


    I also have a couple of digital meters: an L/C meter, and a cheap DVM.

    The oscilloscope (Eico 460) has not been restored (I also have a spare, to cannibalize for parts). I did manage to get it to work, very crudely, and here is my test of a "dual trace" (using the outboard "electronic switch"). The top waveform is the output of a Morse code training oscillator.


    I also have the Heathkit "training courses" for RF signal generator, VTVM, and oscilloscope, which involve both hardware test boards and excellent manuals. One day I will go through them systematically.

    73 de Martin, G3EDM
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  7. G3EDM

    G3EDM Ham Member QRZ Page

    @SM0AOM: Karl-Arne, I almost forgot.

    I also have a gigantic Hewlett-Packard hollow-state frequency meter that uses nixie tubes on the display. The tube count is more than 50 and the thing probably weighs dozens of kilos. IIRC I bought it on eBay from an equipment-rental business in California that was getting rid of obsolete test gear. It is rack-mount IIRC.

    When I turned it on, the nixies lit up, but when I tested it, I could not get a usable frequency read-out.

    Believe it or not, this mad purchase was made because I got interested in having a precise digital read-out for my receiver and transmitter frequencies. But on a whim, I did not want to use any solid-state gear. So this was pretty much the only option.

    Heaven knows what I will do with it. No room in my shack, or my home. But will hang on to it, there might be a role for it some day....

    I also have this nixie frequency meter, but it's solid-state. Coupling it to my regenerative receiver's oscillator was very difficult, basically impossible, but that is what I was trying to do. (However, in the photo, it is loosely coupled to the GDM.) It would be more successful if coupled to the variable LO of a tube superhet, but would have to be heterodyne-converted to display the actual received frequency.

    I think I built a small amplifier to go ahead of this meter, as the RF signals needed boosting to get any display at all. The amplifier was probably a solid-state broadband design, similar to antenna amplifiers. You can see the schematic in the background.


    73 de Martin, G3EDM
    Last edited: Sep 14, 2021
  8. G3EDM

    G3EDM Ham Member QRZ Page

    I found these pictures of my monstrous HP frequency meter. It's an HP-523.

    You can see that I am feeding it with an RF generator, but IIRC all I got was random numbers.

    Maybe one day I'll incorporate it into a digital (but entirely hollow-state) frequency display for my station.

    [​IMG] [​IMG]
    73 de Martin, G3EDM
  9. SM0AOM

    SM0AOM Ham Member QRZ Page

    There is one fuse, and some other diode protection for the movement.
    However, it does not have the mechanical overload relays as the AVO 8 or the Unigor A43.

    My tastes for "flagellation" do not extend to oscilloscopes with synchronised sweeps,
    or to first generation triggered-sweep 'scopes with a "stability" control.

    On my first trainee job in 1975, I got involved with measuring waveforms in a medical diagnostic device using an ancient Telequipment scope. To get steady patterns on the
    scope was well-nigh impossible. At about the same time, I invested in a well-used Advance OS-1000 15 MHz scope, which made a dramatic improvement.

    The major lesson from this was to only use 'scopes with "decent" triggering properties.

    Other test equipment which was early invested in were a Bird wattmeter line-section, a Jones Micromatch, a Magnetic VHF noise source and a Measurements 59 grid-dipper.

    I would say the 80-90 % of the radio engineering problems I encountered during my first amateur radio years in the 70s were handled with those instruments, flashlight bulbs with a wire loops, a small dummy load and a VOM+VTVM.

    The HP523 was a late-50s early frequency counter., and got a successor in the HP524 which counted up to 10 MHz, but could be extended using heterodyne converters.

    When they came on the market in 1961, they changed the roadmap for frequency monitoring at
    transmitting stations. Before such counters were common, one had to measure frequencies "off-air" using instruments related to the BC-221. This was error-prone and time-consuming, so
    when the Administration decided to invest in such counters at the stations it became very much easier to stay within tolerances...


    Former colleague Erik Eriksson at the HP524 some time around 1962.

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  10. G3EDM

    G3EDM Ham Member QRZ Page

    This afternoon and evening started out a bit frustrating (cue to non-Brits: that's code for a major understatement). Without going into the endless details, it is very difficult to "spot" a transmission frequency on a regenerative receiver. It gets totally overloaded. (There is a whole thread of mine on the Homebrew forum that is partly devoted to this issue.) In the worst situation, you really have no idea whether your receiver is set to the same frequency as the transmitter, and because of weird issues with "beating" you could end up being 20kHz off, or even worse.

    At the suggestion of @N2EY (Jim) this is being solved by, during "spotting", running only the transmitter's oscillator and not its PA. This reduces the signal enough that the regenerative receiver is not overloaded. I am in the process of planning the re-wiring of the transmitter so that this becomes a permanently available, and switchable, option.

    So far, so good. Until the transmitter has been re-wired, I have been using a complex "spotting" option involving a second receiver and spotting local oscillators. It seemed to work fine and I was able to score several QSOs using it. But it became progressively harder for some reason. The problem being that, completely baffling me, the transmitter's signal appears not just in one place on the dial but all the way up and down the dial at intervals of perhaps 15kHz. It even appears, say, 15 kHz *below* its correct place on the dial, as well as the correct place, and then 15kHz above, and so forth. There is almost no way to tell which is correct, because they are almost equally loud.

    Tonight I tried something new. I simulated the solution Jim suggested, by removing the 5763 PA tube from its socket. Now, only the 6C4 oscillator is running. "Spotting" is indeed much easier because there is no overloading (thank you Jim!).

    But, those spurs every 15kHz still appear. (!!!)

    My next step was to take The Beast out of the shack and all the way to the other end of the house, with several walls shielding it from the shack. I then blocked the Morse key in continuous sending position (PA tube unplugged), walked to the other end of the house, and swept the dial on The Beast. Still exactly the same problem, regardless of transmitting crystal used: spurs ever 15kHz or so. However, by turning down the RF gain and de-tuning the RF tune control, I was able to get to the point where there was (perhaps) one signal that was louder than the others (a subtle difference, maybe imaginary). When that happened, I marked the dial with the frequency of the crystal in question.

    I repeated this process for the only four "good" crystals that I have for the CW portion of the 40m band (approximately 7005, 7023, 7041 and 7054) and finally ended up with a roughly calibrated dial. At least, I am about 90% sure that it is correct. If not, it will be impossible to conduct QSOs ... because I won't be listening to the same frequency that my CQs are being sent on.

    Wish me luck.... Going to bed soon and would like to sleep through the night so probably no DX chasing overnight. Will send a few CQs now and for the next hour, just to check that things are OK with the calibration. The 5763 PA has been plugged back in, ready for on-air operation!!!

    (If someone can explain why I get those spurs all over the dial ... I would love to know.)

    Edited to add: IF the calibration I did is accurate, then the new spotting configuration suggested by Jim will work fine. The existing dial markings will serve as rough "markers" and then the precise frequency can be zero-beat by spotting.


    73 de Martin, G3EDM

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