It was getting dark, and the auditorium was lit up, and the workers used their leisure time to clean the cigarette butts in the auditorium and the lunch boxes. Hu Wenkai asked Hu Bin to send dozens of cigarettes to the venue, tea leaves, and boiling water.

"Boss, how long are you going to talk? I have already supplied one and a half packs of cigarettes per capita today, which is not enough. ”

Hu Wenkai said in a hoarse voice: "It is estimated that it is at least nine o'clock, and now it is a little more than six o'clock." The following is the hardest part, and even I am not sure that I can explain it thoroughly. This is related to the future development of our company, and we must lay out and cultivate talents in advance. ”

"Boss, let's talk about it tomorrow, your voice is hoarse."

"There's something to do tomorrow, I'm going to go to the engine factory to find old Pete to solve the problem. I'll go back to the office and rest for a while, and you bring the food to the office. ”

Sitting on a chair with the data of the electron tube in his hand, the regret in his heart is that this piece of information is really little, and he did not make much preparation before crossing because the electron tube was replaced by the transistor in thirty years. Last year, he began to prepare a hundred pages of information piecemeal, and by the end of 1923 he had planned to toss the tube computer out and then develop the transistor.

The difficulty is too great, and there is a large shortage of technicians, and there are almost no researchers. It is envisaged that by the end of the year, there will be 300 scientific and technological personnel engaged in electronic technology, and the research and development of radiolocation instruments will be started, that is, radar in the future, and he plans to solidify the name in Chinese.

The prototype of the picture tube has been developed, and it is believed that the first TV will soon appear in Shanghai, and the first TV tower will also be born in Shanghai. With a radiolocator with visibility, the Japanese fleet can be preemptive, and he will have at least a buffer period of ten years to be able to deal with the Japanese fleet.

Drooling from the corners of the mouth and wipe it off with the cuffs. This is not impossible but very likely, and the development of tube technology with sound guidance can be very simple. There were already two submarines of more than 3,000 tons in their hands, which could completely ambush in the ocean and deal a fatal blow to the Japanese fleet.

Steel is the foundation, seamless steel pipe is for the development of the chemical industry and suppress the Japanese steel industry, low-cost seamless steel pipe can directly cut off the urgent need of the Japanese to develop this industry. The fertilizer plant was built for agricultural output and to stabilize the people's morale. The purpose of the tube and electronics industry is to cultivate a group of outstanding electronic technical personnel and lay the foundation for the transistor and future computer industry.

There are still so many people in the auditorium, and it is strange that it should be more than half gone, after all, the next content is like a mountain, and those who have not been exposed to it can't understand it.

"Those of you in the radio and tube industry, please stand up."

Sixty or seventy people stood up in the lower left corner, not bad, but quite satisfied. Think about it and keep asking.

"If you've been in contact with a radio or tube, please stand up."

They all stood up with a bang.,What's the matter, it's impossible to tease me like this.。

"Boss, we've all assembled radios and know a little bit about tubes. In April, the company published radio circuit diagrams and tube introductions in its internal journal, and our radios were all assembled by purchasing parts according to the circuit diagrams. Tian Zhiliang replied below.

"Then let's discuss together, you are interested and can pass the assessment of the Institute of Electronics can be transferred to the electronics industry, and now we will begin to discuss the world's most cutting-edge technology electronics industry."

"The first is an electronic RF amplifier, the tube has a strong ability to resist 100 microseconds of instantaneous pulse overload, and the principle of tube RF power amplifier technology is also very simple."

"RF power amplifiers are an important part of the transmitting equipment. The main technical indicators of RF power amplifiers are output power and efficiency. In addition to this, the harmonic components in the output should also be as small as possible to avoid interference with other channels. RF power amplifiers are electronic circuits that take into account issues such as output power, excitation level, power consumption, distortion, efficiency, size, and weight. In a transmitting system, the output power of an RF power amplifier can range from as small as mW to as large as several kW, but this refers to the output power of the final power amplifier. In order to achieve a high power output, the final preamplifier must have a sufficiently high excitation power level. ”

Drawing the circuit diagram on the blackboard was too much of a struggle for him. It took me ten minutes to barely draw it. In a flash of inspiration, he asked, "Which of you has the best circuit diagram, please come to the stage and help me draw the circuit diagram." ”

"The indicators that measure the linearity of RF power amplifiers are third-order intermodulation intercept point (IP3), 1dB compression point, harmonics, adjacent channel power ratio, etc. The adjacent channel power ratio measures the degree to which the spectrum regeneration caused by the nonlinearity of the amplifier interferes with the adjacent channel. ”

"Since the efficiency of nonlinear amplifiers is higher than that of current amplifiers, RF power amplifiers typically use nonlinear amplifiers. However, a fractearity amplifier amplified the amplification of the input signal while producing a series of harmful effects. From the perspective of spectrum, due to the effect of nonlinearity, new frequency components will be generated in the output signal, such as third-order intermodulation components, fifth-order intermodulation components, etc., which interfere with the useful signal and change the spectrum of the amplified signal, that is, the frequency band is broadened. ”

Someone in the audience raised their hands to ask questions, and he said with a smile: "This section prohibits asking questions, first memorize by rote, and then the people in the audience will come to the stage to answer questions." ”

The technicians in the audience laughed, and there was a buzz that the boss was tired enough for a day, and letting someone who knows how to answer questions on stage can also inspire everyone. In fact, they really don't know that the boss just can't answer at this time.

"From a time-domain point of view, for a modulated signal with a non-constant envelope, the gain of the nonlinear amplifier is related to the amplitude of the signal, so the envelope of the output signal changes, causing the waveform to be distorted, and at the same time, the spectrum is also changed and the spectrum is regenerated. For nonlinear amplifiers that contain nonlinear reactive elements, such as the interpolar capacitance of transistors, there is also the effect of converting the amplitude change into a phase change, interfering with the phase of the modulated wave. ”

There are really technicians who jumped on the rostrum and took the microphone to accept questions from the audience, and after one was asked, a second one came to the stage to answer. He stood aside with a cigarette in his mouth and watched, nodding his head and asking Hu Bin to write down the list.

This was followed by a detailed explanation of the manufacture of practical tube equipment, and in April 1947, the British magazine Radio World published an article by D.T.N Williamson, "Design of High Quality Amplifiers". An excellent power amplifier with large-loop negative feedback is described in detail. This is the "Williamson amplifier" that attracts the attention of the world. Although its distortion coefficient is more than 5%, it has made a very satisfactory breakthrough compared with the old amplifier in many other technical indicators.

He took the microphone and motioned to the technician who was helping with the drawing to draw the drawing on the blackboard.

"I named this high-quality amplifier Tianfen device, the basic circuit of the amplifier is shown in the blackboard diagram, in which VE1 is the input amplifier also known as the pre-stage, VE2 is the P-K split inverter, VE3, VE4 constitute the push stage, VE5, VE6 are the push-pull output amplifier also known as the post-stage."

As soon as the words fell, the technician who understood the line couldn't wait to stand up, jumped on the rostrum, stood in front of the blackboard, and walked along the circuit diagram with his hand.

"In order to meet the requirements of high excitation of the transistor, VE3 and VE4 are added as the driving stage of the power amplifier. From the pre-stage to the post-stage, the bias of each stage adopts a self-sufficient bias with excellent performance; Moreover, the self-supporting bias resistor of each bile cathode is not connected to the AC bypass capacitor, so that it forms an effective AC/DC double feedback. This is beneficial for improving the voltage regulation of the circuit and broadening the frequency band. ”

Due to the increase in the number of series, the self-excitation factor of "Tianfen device" has greatly increased. In order to maintain the stability of the circuit, in addition to the AC/DC negative feedback technology for the above-mentioned bias, special stabilizing resistors such as R19, R20, R22 and R23 are added to the G1 and G2 poles of the final VE5 and VE6 respectively. The output transformer TO has also put a lot of effort into the winding process to prevent phase shift; A large loop negative feedback R21 was added on the secondary side of the TO. In order to broaden the frequency band and suppress the phase shift, direct coupling is used between the input stage VE1 and the inverted amplifier VE2; At the same time, the frequency compensation networks R5 and C2 were introduced. ”

In order to ensure the "synchronicity" of preheating at all levels, "Tianfen device" adopts the valve rectifier power supply VE7. The power supply is filtered using all high-voltage non-polar capacitors, and two LC ripple suppressors are used, so the AC sound of the amplifier is extremely low. ”

There was no need for Hu Wenkai to continue to speak, a technician had already taken the microphone from his hand and began to answer questions. The questions were chaotic, but the answers were quiet, only the voice of the answerer.

The last question focused on Hu Wenkai: "Boss, how much power is this?" How much harmonic distortion does it reach? ”

"Looking at your manufacturing industry, under normal circumstances, it can be stable at the output power reaches 15W, the harmonic distortion reaches less than 3%, and the frequency response is 20Hz~20kHz (-3dB) in the open loop, and 10Hz~100kHz (±1dB) in the closed loop. In addition, the phase characteristics of open and closed loops are also very ideal. ”

"Boss, this day Fenqi is too strong, tomorrow we will organize personnel to produce."

"Okay, okay, let's go down, let's put forward an optimization idea for you to help me improve, I propose a circuit board."

"We're in a mess of wires on the radio right now, with dozens of wires connecting the elements."

"The idea was to print these wires onto a board that made the circuit miniaturized and intuitive, which played an important role in the mass production of fixed circuits and the optimization of the layout of the appliances."

This statement makes all the petrified below, and I don't know what's going on and can't understand it.

Simple, primitive board graphics are drawn on the blackboard, with arrows next to them to name pads, vias, mounting holes, wires, components, connectors, fills, and electrical boundaries.

"Pad: A metal hole used to solder the pins of a component. Vias: There are metal vias and non-metallic vias, where metal vias are used to connect component pins between layers. Mounting holes: used to secure the circuit board. Wire: A copper film for an electrical network used to connect the pins of a component. Connectors: Components used to connect between circuit boards. Filling: Copper pour for ground wire networks, which can effectively reduce impedance. Electrical Boundary: Used to determine the size of the board, beyond which all components on the board can be reached. ”