Пик эпохи регенеративных приёмников в профессиональной и любительской радиоаппаратуре приходится на конец 20-х или начало 30-х годов прошлого века. К началу Второй мировой войны их начали интенсивно вытеснять супергетеродины, а после войны “регенераторы” сохранились практически только в радиолюбительской практике. Несложные в изготовлении и обладающие неплохими параметрами они вполне подходили для самостоятельного изготовления начинающими радиолюбителями.
In 60-ies in Amateur designs beginners Amateurs they replaced the receivers are direct conversion. But in 90-e years again there has been some growth of interest in radio to regenerative receivers. Moreover, some firms even produce such equipment for novice radio Amateurs. It's been a long time, but the interest in these structures in radio is still preserved.
On Figure. 1 показана схема регенеративного KB-приёмника. Его описание было опубликовано в американском журнале QEX в статье “Конструирование высококачественного регенеративного приёмника” (High Performance Regenerative Receiver Design. Charles Kitchin, N1TEV. — QEX, November—December, 1988, p. 24— 36).
Figure. 1
This article analyzed the different ways of adjusting the feedback in such receivers, and noted that the most widespread practical methods that are associated with a change in the mode of regenerative cascade DC — not the best. More stable near the threshold of regeneration work in the cascades, where feedback regulation is performed by the variable capacitor (variable capacitor). It is applied in this receiver.
To avoid radiation of the regenerative cascade to the antenna and to eliminate the effect of its parameters on the performance of this cascade, the receiver has at the input broadband amplifier high frequency transistor VT1. The mode of operation of the transistor DC current is set by a resistor R1 in its emitter circuit.
The regenerative cascade implemented on field-effect transistor VT2. In the original receiver is designed to work in two HF-subbands spanning the frequency band from 3 to 13 MHz. Dual variable capacitor C4 from the portable transistor radio is coarse adjustment on the working frequency. High-frequency sub-band section used С4Ь with a maximum capacity of 140 PF and the low frequency sub-band switch SA1 is connected in parallel to the second section С4а with a maximum capacitance of 365 pF. Accurate tuning is accomplished by condenser C8. The necessary level of feedback set of the variable capacitor with a maximum capacitance of 140 PF.
For stable operation of the cascade the voltage supply +5 V stabilized (diode VD1).
Load regenerative cascade for audio-frequency is the inductor L3. The author used here the primary winding of a miniature filament transformer. Its inductance is unknown, but the total response to the audio frequencies for the reception of CW, SSB and AM stations installed capacitors C12—C14. Capacity choose such that the best reception of CW stations were in the extreme left position of the switch SA2, the SSB stations in its middle position, the AM stations in the far right.
The output of the amplifier of sound frequency executed on the chip DA1 according to the standard scheme inclusion. Switch SA3 to be connected to either the built-in dynamic head or headphones.
Inductors L1 and L2 (Fig. 2) wound on the frame with a diameter of 3.2 cm (used a plastic container from some medications) and contain 4 and 16 turns respectively. The distance between their windings is 6 mm. the Withdrawal of the coil L2 is made from the second (counting from the bottom) of the coil.
Fig. 2
The closest analogue of the 2N2222 transistor VT1 is our КТ3117А. Transistor 2N2222 began to issue half a century ago, but it still can often be found in Amateur radio designs. He has quite a large value, the maximum allowable collector current (800 mA), but here it works when its low value (about 2.4 mA) and why is it you can put any silicon high-frequency transistor with a static current transfer ratio of not less than 100. A close analogue of the MPF102 transistor (VT2) — our КП303Е.
Номиналы резисторов R1 и R2 приведены для напряжения питания 6 В. При напряжении питания 9 В они должны быть соответственно 3,3 и 2 кОм, а при 12 В — 4,7 и 5 кОм.
Материал подготовил Б. СТЕПАНОВ, Moscow
