Vacuum Tube FM Radio Vintage Audio Valve Stereo Receiver DIY/ 6N3/6N1/6K4/6J4. Circuit structure, design principle. This machine belongs to the typical super-external difference radio, using a circuit board design form, including high-frequency reception, mid-frequency amplification, limiting, frequency discrimination, stereo decoding, preamplification and other circuits, the output is a stereo signal, which can be connected to a variety of types of tube power amplifiers, active speakers, stereo equalization amplifiers and other equipment. Specific circuit configuration is as follows: high-frequency reception using dual triode 6N3 to do high-frequency amplification and mixer amplification, dual triode 6N1 to do the local oscillation. Mid-frequency amplification using two-stage pentode 6K4, two-stage limiter, using pentode 6J4, phase frequency identification, stereo decoding using TA7343 (the latest version has been changed to LA3401), the decoded audio signals are switched to double triode 6N2 after conversion switch for 5 times the preamplification, the output of audio signals. Second, the machine highlights This machine has a light weight, high reception sensitivity, the use of electronic tubes to receive FM signals, with a strong sense of nostalgia, the sound sweet, mellow, the use of potentiometers and varactor diode tuning, to solve the need to use the air capacitor to do the trouble of pulling the line system, while the use of digital tubes to display the receiving frequency, the use of 6E2 to display the strength of the received signal to increase the visibility, the ornamental nature. The use of mesh cover design, you can avoid the children at home accidentally touch the scalding. The panel is oxidized by CNC machining, and the shell is made of stainless steel bending and welding. The knob is also CNC processed and polished, high-end atmosphere, the whole machine circuit board is made of 2mm thick PCB, increasing the mechanical strength, not easy to damage. Third, the machine parameters: Receiving band range: FM87-108MHz. Power supply voltage: 110V/220V Number of channels: 2, stereo. Machine power consumption: about 100W. Net weight: about 24Kg Receiving form: super-aberrant type. Four, the machine important components Power transformer, electronic tube, high-voltage filter capacitors, tuning resonance inductor, varactor diode, etc. Please leave note for your special request e. Please do NOT leave negative or neutral feedback without any contact. We care about our valued buyers, if you have any questions, our Customer Service staffs will be very glad to help you.