Audion attempt permission
The audio test permit regulated in the early days of the hearing broadcast the private self-made radio receivers with electron tubes and experiment with permission.
In addition to the audion test permit, there was also a detector test permit . Both permits met the need both for interference-free radio operation and for registration of the radio receivers .
In the term Audion attempt permit, the original meaning of the word Audion as a name for the triode invented by Lee De Forest and named by him has been retained.
Quotes about the audion attempt permit
The trade journal “Der Radio-Amateur” wrote in 1924: “Of the three different ways that open up participation in radio: detector permit, participation by means of officially approved apparatus and audion attempt permit, is for the actual radio enthusiast, ie for the exclusively or predominantly the technical side of broadcasting interested listeners really only the last mentioned in question. ... in order to obtain this permit, applicants must undergo an examination of their technical knowledge and skills. Only when this test has shown that the applicant offers the guarantee that his radio-technical occupation will not disturb the other radio participants and other radio traffic, he will be granted the audion attempt permit. "
"As is well known, the recognized radio clubs have been entrusted with these examinations, the examination conditions have only been specified by the Reich Postal Administration in very large outlines, so that it is essentially at the discretion of the associations which requirements they want to place on the examinees." cited article goes into detail on the appropriate level of these requirements. The “preliminary audion attempt permit”, which was granted without an examination, also plays a role.
The article about the audion test permit also contains the term “the danger of black listeners” and the footnote “Anyone who knows the situation to some extent will know how enormous the number of people who secretly and forbidden work with tubes is today.” The aspect of Collection of license fees apparently played an essential role.
The detector test permit
In the case of the detector test permit, the aspect of registration should have been in the foreground. Little is known that even in the early days of broadcasting it was possible to amplify and generate high-frequency vibrations with the help of certain detectors - similar to a tunnel diode and without a tube.
The technical background
A triode and also certain detectors are able to amplify high frequencies. Amplification of high frequencies regularly leads to the possibility of generating high frequencies and consequently also transmitting them or radiating them as unwanted interference. In particular, the audio test permit is inevitably very close to an amateur radio license or broadcast license. The article quoted says: “This freedom is extraordinarily extensive. Apart from a barely hindering restriction in terms of antenna size, work is only limited by the obligation not to emit any disruptive vibrations. "
From a technical point of view, the audio test permit was about the feedback of the high frequency, which theoretically (and only theoretically) enables infinite amplification and infinite quality . In practice, the essential properties of sensitivity and selectivity for a radio receiver can be achieved with little technical effort (price).
The setting of this feedback by the user was imperative, on the one hand to achieve the highest possible selectivity and sensitivity and on the other hand to avoid self-excitement. Their setting also had to be changed between different stations to be received. Inexperienced operation caused self-excitement and thus the undesired and avoidable emission of radio waves. Sometimes it was also helpful to find the correct frequency setting for the input circuit by “whistling in”; In doing so, the feedback was set supercritically so that beats formed between the transmitter frequency and the local self-excited receiver, which then acted like an oscillator and itself emitted radio waves. However, these whistling tones also annoyed neighboring radio participants and should not occur, for which the holder of the test permit should be sensitized by demonstrating sufficient technical knowledge.
In the case of detector receivers, the antenna's reaction (“reflection”) on the electromagnetic field was discussed in the sense that it is possible to use a detector apparatus to “transmit a borrowed wave” (that is, with the help of vibrations from another transmitter) “(Information to be transmitted).
The end of the audion attempt permit
Due to the tendency towards natural vibrations and the disturbances caused by it, in the early days of radio reception (April 4, 1924 to September 1, 1925), before purchasing an audio receiver or commissioning self-made items at the Reichspost, an audio test permit for RM 60 per person was required Year to acquire. These could only be received by members of the association in the radio cartel who had passed an examination. Do-it-yourself receivers were only permitted from September 1, 1925 without the audion test permit, which also existed as a detector test permit for 24 RM for detector receivers.
swell
- ↑ Dr. P. Gehne: "Die Audionversuchserlaubnis", Der Radio-Amateur, 2nd year, 1924, issue 32
- ↑ Eugen Mittelmann: "The detector as vibration generator", Der Radio-Amateur, 2nd year, 1924, issue 36. The same issue contains further articles on this topic and on the modulation of "borrowed waves".
- ↑ .. for RM-60, -
- ↑ a child of politics
- ↑ and only given to reliable, certified citizens ( Memento from September 27, 2007 in the Internet Archive )
- ↑ History of amateur radio ( Memento from September 13, 2005 in the Internet Archive )