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 Post subject: Soviet Tape recorder MN-61 (sound recording on wire)
PostPosted: Nov Sun 26, 2017 5:38 pm 
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Joined: Sep Wed 23, 2009 8:46 pm
Posts: 73
Location: Moscow area, Russia
A poor quality of sound can be appreciated by watching my video. But the reliability of the tape recorder and the sound carrier exceeds all expectations.

https://www.youtube.com/watch?v=kkGFE_T ... e=youtu.be

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I apologize for the bad English. I communicate with the help of Google translator


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 Post subject: Re: Soviet Tape recorder MN-61 (sound recording on wire)
PostPosted: Nov Mon 27, 2017 1:31 am 
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Joined: Aug Sat 01, 2009 2:23 pm
Posts: 1398
Mihail-1 wrote:
A poor quality of sound can be appreciated by watching my video. But the reliability of the tape recorder and the sound carrier exceeds all expectations.

https://www.youtube.com/watch?v=kkGFE_T ... e=youtu.be


So this is using wire as the recording medium? What is the year this machine was made?

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Antique Radio Club of Illinois


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 Post subject: Re: Soviet Tape recorder MN-61 (sound recording on wire)
PostPosted: Nov Mon 27, 2017 9:18 am 
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Joined: Sep Wed 23, 2009 8:46 pm
Posts: 73
Location: Moscow area, Russia
Please take into account my poor knowledge of English. I ask you to ask questions in a simple form, avoiding complicated verbal revolutions. Jmsent, I did not understand the first question.I'll try to answer as I understood.
The wire transistor tape recorder "MN-61" from the beginning of 1961 produced Vilnius plant "Vilma" and the Rybinsk instrument making factory. The recorder is designed for recording and reproducing speech from a receiver, lines and a microphone in aerodrome conditions or combat units of the Air Force units, as well as for the reproduction of records made on the MC-61 airborne recorder. The sound carrier is a special wire type ЭИ-708А or ЭИ-708. The duration of continuous recording on the cassette is ~ 5.5 hours. The rewinding time of the sound-carrier is about 35 minutes. The unevenness of the frequency response at a frequency of 1000 Hz is not worse than 4 dB, with a change in the input signal from 10 to 70 V from the input of the radio receiver. Uneven frequency response in the frequency range 300 ... 3000 Hz when setting the tone controls in the middle position is not more than 10 dB. The dynamic range is not less than 30 dB. The nonlinear distortion factor of the track is about 10% at the frequency of 1000 Hz. The frequency of the current of erasure and bias is 20 kHz. The output voltage on the loudspeaker type 1ГД-18 is 1.5 V, on phones ТА-56М 1.8 V, on the same, but high-resistance (3.2 kOhm) 20 V. The limits of tone adjustment are not less than 5 dB. When the sound-carrier breaks or terminates during recording, a voltage is output to start the backup tape recorder. The recorder has an autoreclose device that automatically turns off the tape recorder when the input signal ends and automatically turns on when a signal appears during recording. Power supply from a network of alternating current of frequency of 50 Hz voltage 110, 127, 220 V. Power consumption 75 W. The size of the recorder is 326x241x236 mm. Weight 12 kg.
http://www.rw6ase.narod.ru/00/mg_kat_/mn61.html
I removed the coils from the tape recorder and photographed.
Image
Image
Image

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I apologize for the bad English. I communicate with the help of Google translator


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 Post subject: Re: Soviet Tape recorder MN-61 (sound recording on wire)
PostPosted: Dec Sat 02, 2017 9:43 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 285
Location: Beverly Hills, CA, USA
Please contribute more to this forum, your English is good enough for me to understand!

The former Soviet Union has a lot of things that were not available State Side to see until now

I am curious why there was such an emphasis on Germanium solid state, all the way to the early 1990's?

Russian germanium transistors seem to be very robust and have very low leakage, in comparison to ones that were manufactured in other countries


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 Post subject: Re: Soviet Tape recorder MN-61 (sound recording on wire)
PostPosted: Dec Sat 02, 2017 11:45 am 
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Joined: Sep Wed 23, 2009 8:46 pm
Posts: 73
Location: Moscow area, Russia
Omer wrote:
Please contribute more to this forum, your English is good enough for me to understand!

The former Soviet Union has a lot of things that were not available State Side to see until now

I am curious why there was such an emphasis on Germanium solid state, all the way to the early 1990's?

Russian germanium transistors seem to be very robust and have very low leakage, in comparison to ones that were manufactured in other countries



Germanium transistors or silicon transistors are an eternal theme, like the "radiolamp and transistor".
At the end of the century before last, the German chemist K.A. Winkler discovered an element whose existence was predicted in advance by D.I. Mendeleev. And on July 1, 1948 in the basement of the newspaper "New York Times" appeared a short note under the heading "Creating a transistor." It reported on the invention of "an electronic device capable of replacing conventional electronic vacuum tubes
Of course, the first transistors were germanium, and it was this element that made a real revolution in radio engineering. Let's not argue, whether music lovers won the transition from lamps to transistors, these discussions have already managed to podnadoest. Let's better ask ourselves another, no less urgent question: did the next round of evolution go to the benefit of sound when the silicon devices replaced the germanium ones?
The age of the latter was short, and they left behind themselves, like lamps, a perceptible sound heritage. Now germanium transistors are not produced in any country, and they are rarely remembered. But in vain. I believe that any silicon transistor, be it bipolar or field, high-frequency or low-frequency, little signal or powerful, is less suitable for high-quality sound reproduction than germanium. First, let's look at the physical properties of both elements.


Properties Ge Si
Density, г/см3 5,323 2,330
Atomic weight 72,60 28,08
The number of atoms in 1 см3 4,42*1022 4,96*1022
Width of the bandgap, ЭВ 0,72 1,1
Dielectric constant 16 12
Melting point, °С 937,2 1420
Thermal conductivity, кал/смЧсекЧград 0,14 0,20
Electron mobility, см2/сек*В 3800 1300
Mobility of holes, см2/сек*В 1800 500
The lifetime of an electron, мксек 100 — 1000 50 — 500
The mean free path of an electron, см 0,3 0,1
The mean free path of a hole, см 0,07 — 0,02 0,02 — 0,06



It can be seen from the table that the mobility of electrons and holes, the lifetime of electrons, and also the mean free path of electrons and holes is much higher in germanium, and the width of the forbidden band is lower than that of silicon. It is also known that the voltage drop at the pn junction is 0.1 - 0.3 V, and for np - 0, 6 - 0.7 V, from which it can be concluded that germanium is a much better "conductor" than silicon, and, consequently, the cascade of amplification on the transistor pnp has significantly less losses of sound energy than the analogous one on npn. The question arises: why was the production of germanium semiconductors terminated? First of all, because by some criteria Si is much preferable, since it can work at temperatures up to 150 deg. (Ge - 85), and its frequency properties are incomparably better. The second reason, the reserves of germanium are not rare in the earth's crust, its quantity is five times higher than silver, however, germanium is very difficult to extract, because this element almost does not form its own minerals. It is usually found as an impurity to polymetallic, tungsten or nickel ores, and also as an additive in silicates. From there, germanium is isolated as an oxide, which is then reduced with hydrogen at a temperature of 600 degrees. And this, as you know, is a very expensive process - not without reason now the price for one kilogram of germanium is more than 1000 US dollars.
In the Soviet Union, in the production of radio components, special control was exercised and the production of radio components for the army and for domestic purposes was often not separated (simply in the home appliances were radio components that met the weaker requirements when passing through the technical control department). And yet, because of the characteristics of the Russian mentality, many military "ZIP"( spare parts, tools, accessories, designed to perform all types of maintenance, routine maintenance and repair of any products)were after the expiry of the period of storage in the hands of radio amateurs. And when a radio amateur has several boxes of "germanium transistors" he is awakened by a passion for experimentation. In the Russian-language Internet, these "experiments" are many and some have become popular all over the world.

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I apologize for the bad English. I communicate with the help of Google translator


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 Post subject: Re: Soviet Tape recorder MN-61 (sound recording on wire)
PostPosted: Dec Fri 15, 2017 7:08 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 285
Location: Beverly Hills, CA, USA
BRILLIANT EXPLANATION!

Thank you


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