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Amplifier for the speaker "3L"

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Czesław Klimczewski "Amplifier for the speaker '3L'"
Radioamator 1953/01

In the 11th issue of our magazine, an amplifier with two tubes operating in a push-pull system using a transformer that controls these tubes was described. Since this transformer can not always be purchased on the market, its winding presents a certain difficulty - currently the description of the amplifier is given, in which the function of the phase inverter is performed not by the transformer but by means of a radio tube. The amplifier does not have a low frequency choke for current rectification but a resistor with a resistance of 300 Ω and a power of about 5 watts. The resistor is easy to buy or wind up on a porcelain or glass rod.

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Tube amplifier WR75

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Written by "Dziadek" This email address is being protected from spambots. You need JavaScript enabled to view it.

It is now fully functional copy, unfortunately without the original parts. As you can see, power amplifier uses:

  • the beautiful 6P3S tubes at output stage,
  • the 6N8 as a phase inverter,
  • the EF183 as microphone preamplifier and
  • EF80 as gramophone preamplifier.

As the result of long-term "residence" in the wet room, all the paper capacitors were "dead", and so the most of the resistors.

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Negative feedback

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M.R., "Negative feedback"
Radioamator 1954/04

The reason for the nonlinear distortions mentioned in the previous article is the non-linear relationship between the output voltage and the amplifier's input voltage, mainly caused by the non-linearity of the dynamic characteristics of the tubes working in the amplifier. Because at the current stage of development of radio technology we can not build a tube with ideally linear static characteristics, therefore the fight against non-linear distortions must follow a different path, namely to compensate for these distortions by means of special tube circuits.

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Triode as an output tube

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M.R., "Triode as an output tube"
Radioamator 1953/09

The issue of the power stages with the pentode was considered in the previous article (Tube in the amplifier output stage). It boiled down to the proper adjustment of the loudspeaker's resistance, using a loudspeaker transformer, to the type of speaker pentode used. The formula for the optimal anode resistance for the pentode is extremely simple, namely:

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100Bis (PS1) Tube Mixer/Control Panel

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Grzegorz "gsmok" Makarewicz, This email address is being protected from spambots. You need JavaScript enabled to view it.

With a little help of Allegro (online auction site) I became the owner of the 100BIS PS1 tube device. Although I bought it outside the auction but Allegro was unwittingly involved in the transaction. The manufacturer of the device apparently did not attach importance to such a "trifle" as the device name. According to the inscription on the front panel and content of the Instruction Manual I bought a "control panel", and according to the rating plate information and leaflet I bought a "control console". So let me use the following description of the term -"tube mixer".

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