Transistors in the first Soviet radios, especially in Russia
Recently I have been interested in the first transistor radios produced in the Soviet Union and in the Eastern Bloc from the late '50s to the early '60s. Looking carefully at the electrical schematics of these sets I noticed, with some surprise, the employment of only two different types of transistors both in the very first models (starting from 1956), defined as experimental, such as Sverdlovsk, Sputnik, Surprise, etc. . and in the following ones, mass produced and until the mid-60s, such as Atmosphere, Spidola, Neva, Gauja, an so on
For example in the schematic of the model Atmosphere, a MW receiver with an I.F.of 465 kHz taken from the site:
www abetterpage.com/wt/soviet/Atmosphere.html (please copy and paste in the URL-field)
there is the same transistor П402 (P402) both in the RF stage and in those of Intermediate Frequency (IF) while the audio frequency stages use the type П13A (P13A). The same is indicated on the paper label inside this radio as shown in the photo taken from the following russian site:
www rw6ase.narod.ru/00/rp_p/atmosfera13.jpg (please copy and paste in the URL-field)
Similarly, if we look at the schematic of the multiband radio receiver (LW-MW-SW) Spidola (built 1960 in Latvia), a10 transistors radio set with a IF of 465 kHz, we see 8 Russian transistors with the initials П-15 ( P-15) in both the IF and Audio Frequency stages and 2 with the lettering П-423 (P-423) used for RF-stages.
Spidola schematic taken at:
www abetterpage.com/wt/soviet/Spidola.html (please copy and paste in the URL-field)
1) My general question is whether the usage of only two types of transistors can limit the receiver performance, especially in a multi-band receiver such as Spidola.
2) Furthermore, how can the usage of so many types of transistors in Western or Japanese radioreceivers be explained when only a few types were needed in Russian radioreceivers built up to 1963/4?
PS- The letter of the Cyrillic alphabet П corresponds to the letter P in the Latin alphabet
Thank you all for your kind contribution
- Russian early transistor radio Atmosphere_schematic (118 KB)
- Russian transistor radio Atmosphere_transistors list + layout (136 KB)
- Soviet Union early transistor radio Spidola_schematic (130 KB)
Ad1: It depends upon the specification. In the Spinola 2 transistors P423 were used for mixer and oscillator purposes. All the other transi. are P15. Why not use in the LF-Part if the power dissipation for the output stage is sufficient? The IF part contains 1 stage more, compared to classic designs. May be of the performance at 465 kHz.
ad2:This is a guess: Outside the Soviet Union many companies are market competitors. Not so there, because they had no free market, which was controled centrally.
Remark: the upper circuit diagram looks very strange. Also I did not found the supply for the IF stages. May be a failure in the circuit diagram. The selektion with a 3 stage IF filter should be good.
Thanks Rudolf for your observations.
I think it should also be observed that although we have tens of thousands of different transistor part numbers for sale in the West, this is largely an inefficient side-effect of a free-market economy. Manufacturers issue parts that are functionally identical to those of their competitors, and probably just keep issuing 'new' ones for marketing reasons. My own belief is that perhaps 100 transistor types would cover 99.99% of all applications. (The same applies to valves/tubes of course).
Note also that in the USSR transistor types were standardised, so the П13A for example was made by several manufacturers.
You know, this was the specialty of communistic planned economy. On the beginning transistor was an American, imperialistic invention, it means so bad for working class! Everybody, who tried in USSR to reprint any paper about transistor, even that to make research, was suspicious element, thus western spy worthy to send to Gulag! Stalin`s death in 1953 and change of USSR politics in 1956 allowed to make seriouse work on transistors on Easter side to. At these conditions and for 5 years predicted planned economy the developers of new transistor radios were happy to get any type of manufactured transistor. Moreover, it was necessary to make selection of transistors for oscillator circuit to get it oscillate around 1MHz.
In CS and East Germany (DDR) research started a bit earlier, first germanium transistors (1NU70 series) in CS were available in 1955, a bit later OC34 series from DDR. First commercially manufactured transistor radio on Easter block was T58 (based on 152NU70 and 102NU70 series). It was on market since 1958 in CS.
When the economy/plants have limited capacities, then they produced the minimum transistor types: rf one and audio one, you do not need more....
Finally, on Easter side many factories could produce the same type of transistor under the same label, on Western side each company was a competitor to other ones, thus usefull to have different labelling too, even having the same performance.
Thank you for your comments, Rudolph. Yes, the Atmosphere schematic is laid out in an unfamiliar way. It is very like the schematic of a VEF Spidola I was working on recently. PNP transistors take some getting used to! The emitter is positive with respect to the collector. I think that C26 on its negative lead should be connected to the junction of R12, 13,14, as the way the schematic is drawn suggests. That way the IF negative collector rail is supplied from the battery negative via the switches and R14. It’s almost like the designers wanted to confuse anyone (in the West?) reading the schematic!