EAC and DIY precautions SRPP circuit, SRPP circuit introduction
Keywords: SRPP circuit
one. SRPP circuit selection valve
SRPP circuit transplant from fans by the Japanese television VHF band of the last century to the audio amplifier, since excellent sound effects, be universally applied.
Due to the particularity of the SRPP circuit, the choice for the tube has some special requirements. SRPP circuit DC link two three tubes are powered in series, when two parameters are the same three tubes, each tube screen voltage level of power supply half the voltage. For normal operation of the tube in the DC high voltage, low screen tube pressure should be used, for example, DC high voltage power supply is 260V, the work on the selection screen tube pressure of about 130V. This is very important for SRPP circuit.
The circuit structure of the SRPP circuit must be a three-pole tube consistent with two performance, so the double-three tube should be selected so that the electrical parameters are symmetrical. Generally used in three double μ, μ is small because the internal resistance of the tube, screen and stream large transconductance advantageous to reduce the tube output impedance. Further, the tube panels μ three-level characteristics of a wide linear range of the curve, a large range appropriate units of the input signal. Here are pressed screen 130V μ tube in domestic models have a good characteristic 6N1,6N3,6N6,6N11,6N8P, 6N15,6N16B other foreign models 6922, E88CC, E182CC, 12AU7,6SN7,5814A, 6DJ8, these in the low-pressure tube screen has good linearity, non-distorted amplification of the audio signal. In SRPP cathode upper tube at a high potential, approximately 1/2 the supply voltage, this time between the filament and the cathode voltage of the tube has become an important issue, this voltage exceeds, will cause the tube between the cathode filament and breakdown. This issue is also existent to the Sthramic amplifier and the DC amplifier. To solve this problem, for SRPP circuit bis three tubes can be suspended filament power, the filament windings are not grounded, and simultaneously introducing a suitable power supply DC positive access filament winding, will elevate the potential of the filament, and the filament The potential difference between the cathode is small and prevents the breakdown of the cathode. For SRPP circuits composed of two single-triode, only the suspended filament is powered on the upper side of the circuit, and there is no need to speed up the filament potential, but this method is poor.
two. Note SRPP circuit Making
1. Screen pressure is not too high. Usually three double pipe between filament cathode exercise caution when voltage 100V, pressure screen is higher than 100v. When the filament is asked with a pipe with a pipe, the supply voltage does not exceed 200V.
2. Use voltage between filament cathode tube large enough. E.g. made tube 6N11,6N16B-Q, 6N178-Q, 6N16B-Q and 617B-Q is a small tube cord pins, pins directly welded, no header, and a diameter similar to a ballpoint pen, compact, because it was designed that is, military use, good quality. The three-tube filament cathode is ± 150V. 6N1 between the filament cathode tube is made between the withstand voltage of + 125V, -250V, the withstand voltage of the filament cathode 6N6 ± 200v, are suitable for SRPP circuit table. In addition, there is a relatively rare pipes, domestic models are 6H14Ⅱ, Beijing Electronic Tube Factory production, imitation former Soviet Union 6H14Ⅱ model, the former Soviet Union designed for amplifier design series of tubes. Be
3. SRPP circuit must be carefully fine-tuned to work in the best state, the right to set the operating point to a good sound. It is mainly to adjust the cathode resistance to make the two tubes working.
4. Since the SRPP circuit is low output impedance, it is clear that the low internal resistance power of the performance should be powered, so that the circuit can adapt to a large-scale change in dynamic screen, and exert the advantages of the SRPP circuit.
Author: Wang set
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