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

    Never mind. I bought the wrong type of relay: SPST with contacts closed on "energise". What I needed was contacts open on "energise" or alternatively, just a double-throw relay which could be wired in that way. I'll see if I can use this relay anyway, but in that case the RX will have to be muted by shorting a circuit rather than opening it.

    Receiver circuit diagram is in post #605.

    73 de Martin, G3EDM
  2. G3EDM

    G3EDM Ham Member QRZ Page

    OK I found what seems the best solution: shorting out the AF gain control (which is missing from the schematic I posted). Total silence in the headphones.

    Edited to add: Never mind, when I did that, the tube got warm to the touch. Subminiature tubes almost never get warm. When I removed the jumper across the AF gain, it cooled down again.

    73 de Martin, G3EDM
    Last edited: Sep 13, 2021
  3. G3EDM

    G3EDM Ham Member QRZ Page

    OK my bad, I finally found my schematic from back when I added an AF gain control. Shorting out the pot was a stupid thing to do, as you can see....

    My rough schematic from back then was drawn before I had finalized some resistance values. So, I have just taken a look at the receiver and noted down the values of the resistors I finally used.

    Man, I am so rusty at this stuff. Back then I had a reasonable idea how all this stuff worked. Maybe I'm not the only one who looks at a project years later and wonders, how does it work? How did I do that? Why did I do that?

    So your assignment is: find something I can short, that would safely mute the receiver. The schematic is in post #605, except for later alterations and that included adding this AF gain control pictured below. As you can see, I added explicit grid bias from the C-battery. (The original schematic is out of date, it only shows battery grid-bias applied to the RF stage.)


    73 de Martin, G3EDM
  4. G3EDM

    G3EDM Ham Member QRZ Page

    Calling it a day here.

    Today, for the first time in more than two weeks, I haven't been operating at all except early in the day when we (myself and John, @W0PV) came somewhat close to conducting a true trans-Atlantic DX QSO. No big deal for hams in general, except that I am operating QRP, with "vintage" homebrewed equipment, and that my first-ever QSO was only just over two weeks ago.

    Part of the reason I can step back a bit now is that I have evidence that my "new" receiver might (accent on "might") make a measurable difference. We will see. Concrete data are required, mainly: is the QSO rate going to increase?

    With my original rig incorporating the ARRL "3-Transistor Receiver for the Beginner" I was averaging slightly less than one QSO per day. While operating 8 hours or more per day. Well, at least, I was scoring QSOs. Demonstrating that even in the tougher RF environment of the 21st Century that old equipment can still perform. But barely!

    With my "new" more sophisticated regenerative receiver, nicknamed "The Beast", things may get better. The evidence is quite good so far, but only spans a one-day period. We'll see.

    If I happen to wake up early in the morning I'll get up and solicit DX, as I have been doing for some time now, starting at around 0300G.


    73 de Martin, G3EDM
  5. GM3ZMA

    GM3ZMA Ham Member QRZ Page

    A possible muting solution would be to connect a 0.1uF capacitor either across the 500k volume pot, or from the top of the pot to the 0v line.

    Jim GM3ZMA
    G3EDM likes this.
  6. W9BRD

    W9BRD Ham Member QRZ Page

    A for effort! Now you're learning how to troubleshoot MFP (moisture fungus proofed) boatanchor gear and house wiring so old that black and white insulation looks the same. :)
  7. W9BRD

    W9BRD Ham Member QRZ Page

    One possibility would be to open during TRANSMIT the hot (not common) lead to the headphones. This could be quite thumpy on going back to RECEIVE, though, as that 1-uF coupling C may somewhat self-discharge during TRANSMIT and seek to recharge (through your phones) immediately on relay closure back to RECEIVE. Plus that 0.001-uF cap across the phones, having charged in series with the 1-uF cap, will want to discharge through the phones at the same time. (A high-value R -- 47 k? 100 k? -- permanently connected across the phones could minimize this effect.)

    You can dry-run the above to see how bad is bad without installing the relay by enacting TRANSMIT and RECEIVE with a cliplead.

    Another approach would be to (nearly) short-circuit the phones via the relay contacts, in series with -- say -- a 100- to 470-ohm (I'm guessing at starting values) resistor to limit transient current through the 1- and 0.001-uF caps associated with the phones. Maybe no series R at all would work as well.

    As above, you can test out this idea with a resistor and a cliplead -- but in this case be sure to transmit into your dummy antenna to see if the resistor across the phones approach knocks down the keying-the-transmitter thumps and bangs sufficiently in TRANSMIT. We don't need complete silence, just knocking down the noise to the figurative dull roar will suffice. :)

    After rereading some posts: I see that your relay is SPST, normally open. So my first suggestion would require inversion of the relay operation, with relay ON during receive periods -- ungood if you're battery-powering the relay...

    Other options are possible, but I think solutions involving the AF amplifier are the stronger starters. Ac-shorting the AF amp grid to common (with a 0.001- to 1-uF C) during TRANSMIT could work, if with some thumping. Try, try, try!

    You're reminding me of the measures I needed to take when after 1978-1979 winter break I returned to university (at Western Washington University in Bellingham, WA, at the far northestern corner of the state and the "lower 48" contiguous US states) with a built-into-cookie-tins 40ish-watts-input, 20-meter transmitter with a 6AU6 oscillator/6AQ5 driver/3 parallelled 6AQ5s lineup. All I had for receiving was a Panasonic RF-2200 multiband receiver; between my around-the-room ceiling antenna and the Panasonic's all-plastic, no-shielding-possible construction, the thumps and bangs in my headphones were deafening. Radio Shack to the rescue: I used a double-throw relay to route the receiver output into a 10-ohm resistor during transmit. Most fun QSO: One day about 45 min before my first class up the hill I called CQ and was answered by a 9V1 -- Singapore! -- and the op at the other end turned out to be a college professor, who in the ensuing quick ragchew wished me well in my studies while other US stations drooled and waited for me to sign. (BTW, from the "no pressure" department: The FCC's Ferndale, WA, monitoring station was just a handful of miles away, on one of the roads north out of town.)

    Yes: Another really big thing about regen use for two-way operation is the issue of muting -- a point never, ever covered in print (so far as I've seen) during the regen's heyday and since. (My father told me that for many hams -- most of whom used separate receiving antennas in those days -- "muting" consisted of pushing one's headphones forward off the ears. TR switching? What is that of which you speak? :) )
    Last edited: Sep 14, 2021
    G3EDM likes this.
  8. W9BRD

    W9BRD Ham Member QRZ Page

    Oops, the w fell out: "northwestern."

    BTW, in these latter days I occasionally QSO ham's ham and experimenter extraordinaire Steve, VE7SL, just across the strait from Bellingham on Maynard Island, British Columbia. Steve can see the lights of Bellingham harbor at night; I'm surprised I didn't run into him on-air "back then."
  9. G3EDM

    G3EDM Ham Member QRZ Page

    I like it! "Bypassing" the audio without messing with the voltages as I dangerously did by shorting the pot.

    I just tested it and it worked. I don't have a 0.1uF in my pathetic assortment (nearly all my components are in a remote storage unit) but I used the highest value I have, a .022, and it worked fine, the value would not be critical in this case.

    The 1AD4 AF tube does feel a bit warm (compared to the others in the set, which are room temperature to the touch) but I'll just put that down to it handling larger currents than the RF tubes. I don't see how adding a cap in that place could harm the tube.

    Yes I'm up ... I did get five hours of sleep and in a little while will start soliciting that DX again.

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

    G3EDM Ham Member QRZ Page

    I love your stories!

    Inversing the relay operation would use up more battery power, as you say. Everything on the receiver side of things is battery powered (both of my receivers are battery run).

    But more to the point, the existing relay in my other receiver has a muting relay such that "energise" mutes the receiver. This is done by closing the relay coil circuit remotely using a cable connecting the receiver to the T/R switch. If I want to sub a different receiver but use the same T/R switch and its muting-cable socket, I have to follow the same topology.

    (IIRC, in the other receiver, i.e. the ARRL set, muting is achieved by breaking the connection between stages, "opening" the circuit. But in that case I used a double-throw relay. This time around, I was not thinking straight when I bought the relay....).

    Edited to add: As I hinted earlier, it is disappointing how the ham radio literature, modern and ancient, goes light on describing control circuits. They are crucial to station operation!

    73 de Martin, G3EDM

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