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.
C1: 85pF S.M.
C2: 100pF S.M., 100V
C5: 1000pF, 100V
C3,4,7: 10nF, 100V
C8: 2200pF, 250V
X1: 21.060MHz, ESS Type HC49
V2: 1p24b (1П24Б) " " "
- Ground the internal shields (V1 pin 3 and V2 pin 4)
- 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.
- 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.
- I had somewhat better results with V2 pin 1 (the filament common terminal) negatively polarized.
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