On November 27, 1923, American radio amateurs John Reinartz (1QP) and Fred H. Schnell (1MO) conducted two-way transatlantic radio communication with a radio amateur from France, Leon Deloy (F8AB), at a wavelength of about 100 m. This event had a huge impact on the development of global amateur radio movement and short-wave radio communications. One of the decisive factors that influenced the success was the revision of Armstrong’s regenerative radio receiver circuit by Schnell and Reinartz. The improvements turned out to be so successful that for the designs of such receivers, the names “Schnell” and “Reinartz” became common nouns.

It was an ordinary Reinartz ...

The all-knowing Wikipedia about John Reinartz could not tell me anything. This historical essay was written following the scattered publications of American radio amateurs, as well as materials from the January issue of QST magazine for 1924 and issues 23-24 of Radio amateur radio magazine for 1926.

John Reinartz was born on March 6, 1894 in Germany. In 1904, the Reinars moved from Germany to South Manchester, Connecticut, USA. In 1908, John became interested in radio, and in 1915 he was one of the first in the country to join the US National Amateur Radio Association (ARRL).

The era of mastering radio waves has begun. Both the world's leading laboratories and simple enthusiasts searched for technical solutions for radio receivers and radio transmitting devices. As I already wrote in previous articles of the cycle, electromachine generators and crystal detectors were then actively replaced by solutions using electron tubes.

One of the breakthroughs of the time was Armstrong’s invention of a regenerative radio. The solution was simple, cheap, and made it possible to create a device for long-distance radio reception on just one radio tube. The difficulty was in mechanically adjusting the position of the feedback coil. The higher the reception frequency, the more “sharp” this setting turned out to be.

John Reinartz significantly improved Armstrong's circuit by tightening the feedback coil. The feedback value in the Reinartz Tuner receiver was adjusted using a variable capacitor (KPE). To reduce the “severity” of the KPI settings, vernier devices were used.

Unlike Armstrong, who litigated his patents and priorities all his life, Reinartz simply published his design in the June issue of QST for 1921. This was followed by two more articles with improvements.

In the publication of the American radio amateur John Dilks (K2TQN) there is an example of the implementation of a Reinartz receiver on a single lamp:

... and it worked very simply ...

Tube circuitry captivates with the harsh beauty of technical solutions. Everything in its place, nothing more.

In the essay, I specifically decided not to cite the schemes from the publications of the 20s of the XX century, but turned to the textbook first edition of Borisov's Young Radio Amateur. Here is how he simply and clearly shows the operation of a direct amplification receiver on a single lamp:

We examined the operation of the resonant circuit at the input of the circuit and the headphone with a blocking capacitor at the output in the article about Losev's “cristadins”. Let's analyze the operation of the RcCc circuit at the input of a triode amplifier.

The RcCc circuit is called "grid" (from the English: grid leak - grid leak), it is used to perform "grid detection" when the amplifier on the lamp detects the signal and amplifies it.

Graph (a) shows the anode current of the amplifier when the grid is absent. We see that the input signal is amplified directly.

After turning on the "grid" in the control grid circuit, we observe current ripple in the anode circuits (graph b). The blocking capacitor filters out the high-frequency components (graph c), and we get audio signals in the phones.

Now let's see what Armstrong and Reinartz did with this scheme:

Armstrong introduced a feedback coil into the anode circuits of the amplifier. With positive feedback, a signal from the feedback coil is added to the signal in the coil of the resonant circuit. The feedback level is selected so that the amplifier is on the verge of self-excitation, which ensures the maximum level of amplification of the input signal.

When receiving at short waves, setting the Armstrong circuit to work in the regenerative mode was problematic: the slightest movement of the feedback coil led to large changes in the reception parameters.

John Reinartz solved the problem by fixing the mutual position of the coils L1 and L2 so that the mutual inductance between them and the change in the capacitance of the feedback KPE was sufficient for the receiver to work in regeneration mode in a wide wavelength range.

To increase the stability of operation, an inductor Dr was introduced into the anode circuits of the lamp. It provided isolation of the high-frequency circuits of the receiver from the low-frequency ones and effectively filtered out the radio-frequency component from the sound frequency signal.

Verniers were used to “stretch” the frequency and feedback settings - reduction gears between the tuning knobs and the axes of the capacitors. These technical solutions provided a smooth adjustment of the frequency of reception, and most importantly - the feedback level.

When tuning the receiver to a radio station, the feedback level was first set to increase the volume of the air noise. The receiver, in fact, entered the "autodyne" mode, i.e. began to work as a heterodyne receiver. When tuning to the station frequency in this case, a whistle arose first from the beats of the natural oscillations and the carrier frequency. In this way, work was accepted by wireless (CW).

When receiving broadcasting radio stations (AM), the frequency setting was continued until “zero beats” were received, and then the feedback value was reduced, focusing on sound quality.

By the way, an interesting effect was noticed: a regenerative receiver, when inaccurate tuning to a station, often began to adjust the frequency and phase of natural oscillations according to the carrier signal. This auto-tuning provided a synchronous reception mode.

... though not perfect

Regenerative receivers have both a number of advantages and a number of disadvantages.

The advantages include the high price-quality ratio. In addition, the “regenerators” provided a certain universality in use: they ensured the reception of broadcasting stations in the regeneration mode; In auto-generation mode, they worked as heterodyne receivers, and they could receive a wireless telegraph.

The main drawback was the need for constant adjustment of feedback and spurious radiation of the receiver on the air. Remember about Vaska Taburetkina!

After the war, regenerative receivers began to be superseded by superheterodyne. But that's another story…

From the author

In the 1920s, John Reinartz studied short wave propagation. Been on an Arctic expedition.
Since 1933 he worked at RCA.
In 1938 he entered the Navy, and ended his service in 1946 as captain.
In 1946 he returned to work at RCA.
Since 1949 he worked at Eimac.
On February 1, 1960, a grand banquet took place on the occasion of Reinarz's retirement, in which more than two hundred eminent radio amateurs took part.
He died on September 18, 1964.

Used sources

1. "QST", 1924, No. 1
2. "Amateur radio", 1926, No. 23-24
3. Borisov V.G. Young radio amateur - Moscow: 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

John Reinartz and his legendary radio