Tuesday, July 19, 2011

Sputnik QSO Party Transmitter Prototype

Here is my Sputnik QSO Party transmitter prototype. The RF output power is 450mW with 70Vdc @ 14.4mA on the V2 anode. The V2 screen (G2) current is 1.6mA. The V1 anode current is 1.05mA with 45Vdc @ 176uA at the screen (G2). These little vacuum tubes are capable performers, however, for long-life operation it's important to heed the maximum electrode ratings as shown on the datasheets (links given below). 

The simple MOPA (Master-Oscillator -> Power-Amplifier) vacuum-tube radio transmitter circuit shown below was well-known in the mid-1950's. A crystal-controlled Pierce oscillator drives a Class-C PA. The PA grid bias is derived from rectified PA grid current (thus; never run the PA stage without the oscillator drive signal present!).

The CW keying and transmit/receive switching circuitry are not shown in the circuit below. Please click here to listen to a strong-signal recording of the original Sputnik-1. The oscillator signal bleed-though during "key-up" intervals is clearly audible. This implies that the oscillator stage was allowed to run continuously. Presumably, only the power amplifier (PA) stage was keyed on/off. As such, I plan to only key my PA stage (via the anode supply or perhaps using grid-block keying). My oscillator will be switched off only while I'm receiving signals. 

Parts List
C1:     85pF S.M.
C2:   100pF S.M., 100V
C5: 1000pF, 100V
C6:     10nF
C3,4,7:  10nF, 100V
C8:    2200pF, 250V
R1:    27k
R2:    68k
R3:   100k
L1,2:  67uH 
L3:  3.3uH
VC1:   5-35pF
VC2:   20-150pF
X1:  21.060MHz, ESS Type HC49
V1:  1sh24b (1j24b or 1Ж24Б) ex-Soviet sub-miniature "rod tube"
V2:  1p24b  (1П24Б)      "                     "                      "

  1. Ground the internal shields (V1 pin 3 and V2 pin 4)
  2. A low-pass filter may be required between the Pi-network impedance matching circuit and the antenna. I have not yet checked the RF output spectrum, however the inherent Pi-network 2nd harmonic attenuation is only ~28dB.
  3. The value of C1 may have to be adjusted for your particular circuit layout. This capacitor helps both to maintain the optimum level of oscillator feedback and provide the proper loading capacitance for the quartz crystal resonator.
  4. I had somewhat better results with V2 pin 1 (the filament common terminal) negatively polarized. 
 The drawing below shows the original Sputnik 1 keying plan for normal conditions; 0.3 seconds on, 0.3 seconds off. While the 40.002MHz transmitter was off the 20.005MHz transmitter was on, and vice versa. This helped to hold the battery load steady.

    DL3JIN has made a wonderful job of his Sputnik Sender; details of which may be found here. Well done, Peter!

    Roger, G3XBM and Andrew, G6ALB posted details of their Sputnik-1 transmitter project here

    Here's a short video on the topic of these Soviet "Rod Tubes" (dig the Cosmonaut on the intro screen!). Of these amazing sub-miniature vacuum tubes, Dmitri Faguet writes (post #12)

    "The 1j24b is a universal ultra low power miniature HF pentode designed in the mid 1950’s as part of the series of so-called Rod Tubes, invented by Russian engineer and academic Valentin Avdeev, who worked at a special vacuum tube research and manufacturing plant code named “No.617”, located in Novosibirsk, Russia during and after WWII. For many years, Rod Tubes became the backbone of Soviet military and aerospace electronics, with more than 200 million Rod Tubes manufactured without any modifications for nearly four decades from 1950’s to 1990’s. All Rod Tubes were low power battery operated pentodes with one or two thin 1.2 V filaments, and with other rod-type electrodes rigidly located at very small distances from each other."

    David, NM0S, is building his Sputnik clone into a metal earth-globe. How clever!



    Sputnik-1 and Amateur Radio
    Sputnik Declassified: Nova, 2007 documentary
    Spaceflight Magazine: Vol 49 November 2007 
    Volkssternwarte Muenchen; thanks to DL4ZAO for the excellent link!
    Sputnik Model Plans; from The Arizona Model Aircrafters 
    October Sky (required viewing for Sputnik QSO Party participants ;o)
    The Top Ten Sputniks
    Dr. Asif Siddiqi's Research Pages; my thanks to Chris, OE3HBW
    More Sputnik-1 Info; Tnx to OE3HBW
    Pull Apart the PS-1; Tnx to OE3HBW  


    1. Do you really think there are only two tubes in this transmitter? Currently I translate all your messages to german for the QRP Forum (qrp-forum.de > DL-QRP-AG > Sputnik Projekt) and I see another white tubesocket on the closeup of the transmitter. I think there is a third tube in it ... What about an astable multivibrator and a PA with the third tube? (Would fit to the actual Sputnik sound -> http://www.youtube.com/watch?v=lPFKd5p_t0s&feature=related ).

    2. Hello OM,
      I agree there must have been at least one more vacuum tube used for the purpose of alternately keying the VHF and HF transmitters. Again, my guess is that two vacuum tubes were used in the actual RF producing circuitry. Given that the battery accounted for 61% of the total satellite mass, there would have been an incentive to reduce the number of continuously heated filaments to a minimum.

      Mike, AA1TJ

    3. Oh, iam sorry! I actually did not mention my name because I was totally flashed by the awesomeness of the project! My name is Jan (or DL8JAN).

      Well, there's plenty much translation to do .. I will stay tuned (and correctly matched!)!
      73s, de DL8JAN!

    4. Hello Jan,

      Thanks so much for your very kind assistance! I look forward to working you in the Sputnik QSO Party coming in October. It's going to be wicked cool!

      Mike, AA1TJ

    5. Hi Mike,

      Iam sorry, but Iam not compatible with CW. :-(

      Because Peter (DL2FI) is quite busy - Would you add me to your Mailinglist (Mail: j.krueger@kaltmacher.de) so I can copy, translate and post to the QRP forum directly?
      (I hope I don't have to face a flood of messages)

      Too bad, that I have almost no knowledge about tubes and electronics!

      72 de DL8JAN

    6. This comment has been removed by the author.

    7. Dimitri Turbiner provides a translated version of the 1P24 Tube data:

      73, Guenter

    8. On the page of the "Volkssternwarte Muenchen" (Munich public observatory)
      (in german language only)

      I learned, that the signals from Sputnik1 carried telemetry signals. The inner temperature was coded by the tone frequency and the pressure of the nitrogene atmosphere changed the length of the pauses.

      The guys in munich did a FFT Analysis of an original recording from 1997 to restore the telemetry transmissions based on a calibration curve from the 40th anniversary Project "Sputnik 40".

      73, Guenter

    9. Hallo Guenter,

      Yes, I had read about the basic telemetry functions that were hastily built into the Sputnik-1 (PS-1) but the Volkssternwarte Muenchen site is full of excellent information...thanks so much, OM! I'll add it to the above list of links.

      By the way, I especially enjoyed reading about Heinz Kaminski, DJY5M. Peter, DL2FI, was telling me about this guy a couple of months ago in Friedrichshafen but I'd never heard of him before.

      Again, thank you for the wonderful links, Guenter. I look forward to linking up with you across the "October Sky"!

      Auf Wiedersehen,
      Mike, AA1TJ

    10. G6ALB and I managed to build a version today Mike. Successfully tested over a 3km path between us. A second Sputnik is planned for Oct 4th so we can work each other and maybe some others at greater range. Thanks for the valves and crystals.

    11. Congratulations and well done on your first homebrew valve project, Roger! I look forward to working both you and Andrew in October. Let's keep our fingers crossed for favorable 15m propagation.

      You're quite welcome, OM.

      Best wishes,

    12. I've just tried "grid block" keying the PA, it seems to work quite well.

      To add that I lifted the earthy end of R3, decoupled it to ground with 10n and added another 100k to that point with the other end of the new 100k connected to a -35V rail I have here.

      The key goes between ground and the junction of the two 100k resistors. So key down the negative bias is removed from the PA tube allowing it to conduct, key up it is cut off.

      Carrier suppression key up is about -35 dB WRT the key down power.

      Roger and I keyed the PA HT in our tests to date, which works well but puts 70v on the key which may not be to everyone’s tastes.

      Using GB keying one side of the key is grounded and the other side has -35V on it through a 100k.

      Doubtless other negative voltages will work, but they have to be enough to make sure the PA tube is cut off with the osc drive present.

      We’d previously found keying the whole rig was a bit chirpy and so preferred to leave the osc running and key the PA in some way.

      As a bit of an occasional operator I have to say I’m *very* much looking forward to giving these rigs some exercise on the 4th October. Some DX would be magic!

      73 es GL!


      PS: Thanks for sending the parts Mike, much appreciated here.

    13. Hello Andrew,

      Thanks for the good info; especially as I haven't yet gotten around to keying my own Sputnik.

      I'm getting excited here as well Andrew. RV3GM tells me there are at least three Russian Sputnik clones under construction there. "Kits" went out to Japan, Zimbabwe, Finland, the Netherlands, Germany, Canada, and thanks to Colin/G3VTT a number of Cubans are busy building their transmitters. David/NM0S is building his Sputnik transmitter into a metal earth globe(please see photo above)...very cool!

      I'll certainly listen for you and Roger in October, Andrew. Thanks so much for joining in the fun. See you soon on 21.060!

      Mike, AA1TJ

    14. Hello everyone,

      I have my bits and piece to hand and will soon have a Sputnik QSO Party TX on the air - hopefully for "Blast Off Day"!

      I too had the idea to build my TX into a sphere however I was thinking of going a bit further in putting a 15 meter V dipole on the sphere and mounting the affair on a pole - My own earth bound Sputnik "clone". Alas, time is not on my side and I will not be able to put something like this together before October.

      cheers, Graham ve3gtc

    15. Michael,

      Is it possible to get the rod tubes for this project from you? I would like to join the fun and put one of these on the air too.

      73 -Dan WA6PZB

    16. Hello Dan,

      I'll stop at the post office on my way to work today in order to send you a set.

      Good luck and I hope to see you on October 4!

      Mike, AA1TJ

    17. Wow, super! Let me know what I can give you for your trouble.

      -73/72 Dan WA6PZB

    18. Hi Graham,
      Vy FB...GL OM!

      I hope the tubes arrived safely. A Sputnik/Sputnik QSO come next Tuesday would repay me with dividends ;o)

      Beep beep,
      Mike, AA1TJ

    19. Michael,

      Are there any spare valves still available?
      I'm as the crow flies about 40 miles west of Roger G3XBM.



    20. Hi Dom,

      I'm sending you my last spare set. In fact I'm headed to the post office as soon as I sign off.

      Good luck and have fun.

      Mike, AA1TJ

    21. Mike,

      All parts put together and hope to have this qrv later today or tomorrow 16th/17th October. I might also try it on 20m. My C1 is a ceramic trimmer.

      The PSU I have up and running from G3XBM & G6ALB advise. Using 24AC voltage (Linear not SMPS rated at 1.5A) that is doubled and rectified to produce DC +74V HT for V2, using a series resistor I drop this to 52V for V1. Using the same 24AC supply obtain -37V and will grid block key as per G6ALB advice. My heater supply is a mobile phone 5V 500mA USB supply and a number of 5W wirewounds in a resistor chain until the voltage is dropped enough to just below 1.20V. Andy was keen to advise don't reach for an alkaline battery as they are sometimes 1.6V new which might kill the tube.

      The V2 valve 1P24B pin out... I think I have this correct but can you confirm as the base is not quite as per the spec sheet.

      Looking down on base (so wires coming at you).
      With the black mark on bottom and the three ping in a line horizontal). The empty pins at top and right.

      Then reading clockwise from bottom:

      1, 2, 3, 4, (top) 5 is missing, 6, 7, (far right) 8 is missing and 9 in centre.



    22. Mike,

      Build almost complete I worked out the pins.




    23. Hello Dom,

      I'm sorry not to have answered sooner but I just got in from work a short while ago.

      Ah, you've already figured it out....and you're nearly QRV to boot. Good man!

      I'll be tying up loose ends for a trip out of town on Tuesday. But if you could let me know when and where you'll be on 15m tomorrow, I'd be more than pleased to attempt a cross-pond, 2X Sputnik QSO!

      In any case I hope you'll send some photos of your setup. My email address is mjrainey "at" gmail.com

      Congratulations and Good Beeping!

      Mike, AA1TJ

    24. Mike,

      I was sent a small collection of valves so will return a pair to you Monday 1st.

      http://m1kta-qrp.blogspot.com/2011/10/qrp-sputnik-from-m1kta.html and later posts have photos of mine.

      I will also have mine qrv on G-QRP valve day (November) and as I have some extra valves will also put one up on 80m or 20m.



    25. very interesting info abt SPUTNIK-1. Many thanks . 73 de RX1AG

    26. Dom,M1KTA; I received the set of valves from you. Thanks very much!

      Val, RX1AG; Thank you for your comment. I enjoyed looking at your web pages. Good luck with the 6P3S Club!

      Mike, AA1TJ

    27. Mike, thank-you for this great article! I'm one of those who are trying and get ready for this year's Sputnink QSO Party. I'm building my own transmitter and it looks like it is working, but I've still got to properly tune it up. Can you tell me what is the amplitude of the RF voltage that you have on the anode of V1 ? I'm getting about 4 volts rms, but I built mine according to the following schematic, that is a bit different from yours:



      de Carlo/IZ4KBS

    28. Direkt auf. Es ist mehr informativ und leicht zu verstehen. Vielen Dank so eine schöne Leitlinie ......

      pa verstärker

      pa endstufe


    29. hello,...nice mini qro cct,...