This publication completes a series of historical essays on the heroic era of the battle for short waves and the development of tube electronics.

The heroes of my essays were romantics. Fyodor Lbov was not afraid of criminal prosecution for broadcasting, Ernst Krenkel risked his life in the Arctic, John Reinartz simply published his developments and did not patent them. They were truly fearless: they switched the anode circuits of the transmitters with telegraph keys; hands tuned the frequency of the transmitter by compressing and stretching the coils under voltage; considered a working moment when the lamp "gave gas" and exploded.

Life did not stand still. In preparation for the Second World War, the technological process for the production of radio tubes was significantly improved. Schemes have been developed for simple and reliable HF transmitters using commercially available lamps. The romanticism of short waves entered a stage of maturity.

Life began to improve

March 9, 1946 a document signed by the Deputy Chairman of the Council of Ministers of the USSR V.M. Molotov's amateur radio returned to the legal field. Following this event, the Committee of the USSR Osoaviahim created the Shortwave Radio Amateur Committee, which was headed by the marshal of the communications troops I.T. Peresypkin (sic!). Deputies approved engineer Vice Admiral A.I. Berg and Hero of the Soviet Union E.T. Krenkel.

Radio receivers seized during the war began to be returned to citizens. The issuance of work permits on the air resumed.

In May 1946, the first issue of Radio magazine was published, where Ernst Krenkel published an informational message about the organization of the Central Radio Club (TsRK), and Fedor Lbov posted a note on R1FL. Marshal Peresypkin, Admiral Berg, Academician Kapitsa, Papanin heroes, engineer Shaposhnikov, and many more respected and noble people also “noted” in the issue.

Since 1947, Gosenergoizdat began to publish books in the series “Mass Radio Library”. The next part of the essay was written based on the issue 162 (Kazansky I.V. How to become a shortwave) with the subsequent analysis of the circuit based on the materials of issue 125 (Shulgin K.A. Construction of amateur short-wave transmitters).

DANGEROUSLY! HIGH VOLTAGE!

APPLICATION OF RADIO FREQUENCIES AND HIGH-FREQUENCY DEVICES WITHOUT PERMISSION TO USE RADIO FREQUENCIES RESPONSES AN ADMINISTRATIVE RESPONSIBILITY.

Beginner amateur radio transmitter on 6P3S

In those days, there were no transceivers or frequency synthesizers. An ordinary amateur radio station consisted of a separate receiver and transmitter.

In order to conduct a radio communication with another radio amateur, you had to tune your transmitter to its frequency. And it was not easy! Having received the signals of another radio amateur on his receiver, it was necessary to approximately set (but it is not possible to determine on the analogue scale exactly) the transmission frequency, and then by adjusting the transmission frequency, to receive the signal of his transmitter to his receiver at the correspondent frequency.

Let's go back to the 6P3S transmitters. The outline below was published in 1952. It is extremely romantic: the source of the anode voltage is assembled on the kenotron, the master oscillator (ZG) is used immediately as a final stage, and there is no ammeter in the anode chains. Enjoy:

However, using this transmitter does not require heroism. With the housing closed, the chances of getting under voltage are minimal: the “inductive three-point” and the variable capacitor (KPE) in the master oscillator are connected to the cathode circuits, and the telegraph key is also connected there.

When the telegraph key is open, the oscillations of the ZG are disrupted. When you press the key, the triggering process starts, and oscillations with the resonance frequency of the circuit L1C4 appear in the antenna circuit. R2C3 parallel to the key provides a smooth start of the , which makes the output signal less “chirping”. The form of the output signal when switching without R2C3 chain is shown in graph a), with a chain in graph b):

According to the shape of the output signal, we see that when you press the key, an unmodulated carrier or CW (Continuous Wave) is broadcast.

The fact that “self-control”, i.e. adjustment of the transmission frequency can be carried out only by a signal that is already on the air! For comparison, I will give a much more practical scheme of a category III transmitter from Shulgin’s book:

ZG and the final stage are implemented on different lamps. ZG supply circuits are stabilized. An ammeter is included in the anode circuits of the output lamp to control the current. The telegraph key is connected to the cathode circuits of the output stage.

The PG in the circuit from Shulgin’s book is always on; it’s not a problem to determine the frequency of the transmitter’s adjustment by the monitoring receiver. Shulgin's circuit is much more convenient in operation, much more stable in frequency and better in waveform, but there are already two lamps in it.

Unexpected direction of development of the transmitter on 6P3S

In the 60s, there was practically no romance in connection with HF. Amateur radio communication has become a sporting discipline. It became crowded on the air, and radio amateurs switched to communication with single-band modulation modes. Transceivers began to be widely used, and there was no need to adjust the frequency of the transmitter.

The remnants of the romantics fiercely resisted technological progress and used transmitters with amplitude modulation already outside the legal field.

Amplitude modulation of the signal is carried out using a modulator. Here is a block diagram of an AM transmitter from Shulgin’s book:

According to the signal from the microphone, the AM modulator changes:
- either the power supply voltage of the final stage (anode modulation),
or the displacement on the grids of the final stage (grid modulation).
The best results are obtained by modulating the control (first) or protective (third) grids. Anode modulation was somewhat easier, but it did not give the quality of a grid.

The most indestructible romantics used an amplifier of a tape recorder, radioola or radio transmitter as an anode modulator. In this case, plus power to the output stage from the circuit in the book of Kazan was supplied from the anode of the output lamp of the amplifier. Compared to the circuits with grid modulation, the signal quality suffered, but this did not stop the real romantics. And the name of such products was romantic: "barrel organ"!

From the author

I started on air in 1979 at a collective radio station. We used the tube version of the UW3DI transceiver. They worked mainly with single-band modulation (SSB). Everyone knew the telegraph, but they were not so interested in working.

I was interested in development, design and debugging. My comrades were more occupied with diplomas and prizes in competitions. No romance ...

Used sources

1. "Radio", 1946, No. 1
2. Kazan I.V. How to become a shortwave - M .: Gosenergoizdat, 1952
3. Shulgin K.A. The construction of amateur short-wave transmitters - M .: Gosenergoizdat, 1951

Other cycle publications

1. Nizhny Novgorod radio laboratory and amateur radio communications on HF
2. Nizhny Novgorod radio laboratory and radio receivers with crystal detectors
3. Nizhny Novgorod radio laboratory and “cristadins” Losev
4. John Reynartz and his legendary radio receiver
5. 6P3S transmitters and the sunset of the romantic era

6P3S Transmitters and Sunset Romanticism