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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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A simple, pocket, radio station for the village. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Civil radio communications

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As a rule, all schemes of portable radio stations published on the pages of "RL" are designed for a city dweller, for his ability to get scarce elements, rare microcircuits. And for us, the villagers, it is very difficult to repeat a different design. Meanwhile, personal radio communication is relevant precisely in villages and villages, where even now one telephone set is sometimes installed for the entire district.

I myself am a rural resident, and therefore, when developing this design, I tried to take into account our problems with the availability of the element base.

The radio station consists of two parts: a transmitter and a receiver. The transmitter is assembled on a 1,5 mm thick fiberglass board measuring 100 mm x 45 m. The receiver is 60 x 45 mm. Why are there two fees? The fact is that these are two independent designs that can be improved independently of each other. There is one more detail. This design very easily turns into a radiotelephone, since the receiver and transmitter can work simultaneously if they are detuned relative to each other.

The transmitter circuit and coil data are shown in Fig. 1.

Simple, pocket, for the village radio station
(click to enlarge)

The transmitter is assembled on five transistors. Two transistors - in the modulator. Three - in the transmitting part. Transistors are not critical in selection. Any silicon can be used in the modulator: KT315, KT503, KT306, i.e. usually those that can be soldered from old receivers, tape recorders.

The master oscillator also has a wide selection of transistors. KT315, KT306, KT316, KT368 work well here. Quartz - at 27 MHz. In the second stage, KT603, KT604, KT605 work well.

In the power amplifier, you can use transistors such as KT610, KT606, KT907, KT922.

All transmitter coils are wound on IF circuits from industrial radio stations or radio receivers. Coils - with screens and cores. They are very easy to set up, you just need to have a simple wavemeter.

The setting begins with the master oscillator - according to the maximum deviation of the wavemeter needle. The second and third stages are set up in the same way.

The transmitter works confidently on a 7D-0.125D battery, which is also important for a rural radio amateur.

The modulator uses a DEMSh-1 capsule instead of a microphone.

The receiver has always been a difficult device for a rural radio amateur, because, as a rule, it is a superheterodyne. And to set it up, you need devices and microcircuits, which are not available in the countryside, and the nearest city is 180-200 km away. Therefore, my opinion: the best way out is a super-regenerative receiver. For all its simplicity, it has a rather high sensitivity: up to 5 μV, which is not inferior to the "super". The use of UHF not only increased the gain of the receiver as a whole, but also solved the problem with spurious radiation. The receiver circuit is shown in Fig.2.

Simple, pocket, for the village radio station
(click to enlarge)

The K174UN4V microcircuit was used as an amplifier, which is sufficient for loud-speaking radio communication. Its setting is available even to a beginner.

Any RF transistor, both silicon and germanium, can work in the first stage of the receiver. for example, KT306, KT368, KT316, KT315.

The second stage is the regenerator. There are problems here. In these stages, only germanium transistors usually behave well, so GT311 Zh, A, C, B work here. The use of silicon transistors gives unstable results.

A properly assembled receiver begins to act immediately, and the indicator of its operation is noise.

They tune it to the transmitter from their own design for the disappearance of noise. The final tuning is carried out already at the maximum distance of the two radio stations from each other.

The antenna used is spiral, the design of which was given in "RL" No. 5/92, p. fourteen.

I have collected two radio stations that have been serving faithfully for three years. Confident range - 2,5 km - 3 km.

When working in stationary conditions and powered by 12 volts, as well as when using an external whip antenna, the range reaches 10 km.

I do not give printed wiring, because due to the wide range of parts of this radio station, the dimensions of the boards can be arbitrary.

Author: F. Zhupanov, Moldova, town. Taraclia; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Civil radio communications.

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Sleep Consumption 600nA (with timer)
Fast wakeup and fast synth setup time
Automatic retries and confirmations
Suitable for Wireless M-Bus systems; 802.15.4g
Case 4x4 mm QFN
Operating temperature -40...+85 °C

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a guest
And in the L4 coil, how to count the taps - from left to right or from right to left?


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