Siheyuan: Starting from a Truck Driver

Once a radio station stops broadcasting, all that's left is the noisy sound of electricity. If you give Ye Zi a crystal radio as a gift, she might think it's inappropriate. "

"If you really want to give me a tube radio, I can buy it directly from a department store. Let me explain it this way. Ye Zi is going to the northwest with Professor Wang to explore for minerals. That place is remote and it is inconvenient to buy batteries. So I plan to make a crystal radio for her."

"Great, really great, Lao Hu's skill in coaxing girls is really first-rate, I admire you deeply."

"Don't talk nonsense, Ye Zi and I are purely friends."

"Old Hu, you are just shy. Now is a new era, and it is common for men and women to date and fall in love."

...

Li Xiaodong turned around, a hint of joy flashing across his black eyes.

The three people were students from the Department of Physics at Tsinghua University, and they were also avid fans of mineral processing machines.

A crystal radio is a wireless receiver that does not require a power source, uses crystals for detection and a tuning circuit.

Because of its low cost, the ore machine can be assembled by hand, does not require batteries, has a long service life, and does not require maintenance costs, it is deeply loved by the people.

Although the ore machine has many advantages, it has not been widely popular for a long time and also has major defects.

Receiving radio signals requires patience in finding the sensitive points of the ore, and not all ores are suitable. People often spend a lot of resources to buy ores, only to find that the ore machine cannot receive signals.

Therefore, the technical threshold for producing ore machines has gradually increased.

Most of the people who made crystal radios were radio enthusiasts. In that era, owning a radio was as luxurious as owning a luxury car, which meant having a certain level of cultural literacy and financial strength, like Hu Guangliang.

While Li Xiaodong was working as a temporary worker, Hu Guangliang often came to buy raw materials needed for the ore mining machine, and the two gradually became familiar with each other.

He knew that Hu Guangliang came from a military compound, and the two people around him also came from ministry compounds.

In addition to money, the key is to obtain a letter of introduction for the purchase of chemical materials. Just as you need food coupons to buy food, meat coupons to buy meat, poultry coupons to buy old hens, bicycle coupons to buy bicycles, and even industrial products such as toothpaste, steel pots, enamel basins and flashlights also require corresponding industrial coupons.

组装矿石机所需的矿石、电容（2200皮法）、高阻耳机、2AP9二极管、1N60二极管、漆包线、电线以及可变电容等均为管控物资，需凭借单位的介绍信在化工原料门市购买。

Ordinary people simply cannot obtain these channels, which is why Li Xiaodong is looking forward to the three students from the Department of Physics of Tsinghua University. They are members of the radio experiment team and hold letters of introduction issued by Tsinghua University.

"Sister, start preparing a set according to the materials on the list." Hu Guangliang shook the letter of introduction in his hand, and then handed the list to Sister Niu. The production of ore machines is extremely complicated and often ends in failure.

He was determined today, no matter how much it cost, to help Ye Zi assemble a crystal receiver that could receive broadcasts from Beijing.

"Okay, wait a moment."

They are all regular customers. The consumption of students from Qinghua University here has exceeded four or five hundred yuan. Sister Niu did not look at the letter of introduction carefully. She took the list and went directly to the warehouse to get the materials.

As soon as she left the counter, she was stopped by Li Xiaodong: "Sister Niu, I have nothing to do and I am familiar with the warehouse. Let me go."

"Okay, then I'll treat you to lunch and bring my niece along." Sister Niu said half-jokingly, eager for help.

...

李小东在化工材料店做了整整三年的临时工，闭着眼都能找到所需的材料。辉铜矿石、电容（2200皮法）、高阻耳机、2AP9二极管、1N60二极管、漆包线、电线、可变电容……

Within five minutes, Li Xiaodong went out with a bamboo basket full of materials.

At this time, Hu Guangliang and the other two had already paid and were sitting at a small table near the wall of the store. In addition to them, there were four or five young people who looked like college students gathered there.

Although Li Xiaodong didn't know their names, he knew they were all radio enthusiasts. Making crystal radios was a niche and elegant hobby, just like playing racing and participating in the feast of the sea and sky in later generations.

Similarly, enthusiasts also need to communicate with each other. The side room of the chemical material store has several tables and tea, which is an ideal place for communication.

After hearing Hu Guangliang's plan, the young people all offered suggestions.

"Materials are crucial, Lao Hu, don't be reluctant to spend money."

"I heard from a friend in a military factory that the Q value of the military's 222 air variable capacitor can reach . If you use this, you will definitely be able to receive two more radio stations."

"That's right. The chemical material stores only sell common goods. It's better to go to the laboratories of military factories and have a look."

...

The person who spoke was a young man in a general's uniform. Li Xiaodong recognized him but didn't know his name.

Everyone called him Lao Bai. He always wore a general's uniform and a small military cap, looking very arrogant.

In the past, Li Xiaodong might have just laughed it off, as he could have been more relaxed if they weren't tinkering around in the store. But today was different.

...

"Old White, the performance of air variable capacitors is not necessarily better than that of small sealed capacitors." This unconventional remark sounded like thunder in everyone's ears. They all turned their heads and saw a young man standing there quietly with a bamboo basket. Although he was wearing a worn cotton coat, his temperament could not be concealed.

The first person to react was Hu Guangliang.

He stood up, with a look of joy on his face, walked over and waved at Li Xiaodong: "Xiaodong, you are wearing an old cotton-padded jacket today, I almost didn't recognize you just now. Where have you been during this period? I came here several times but couldn't see you. I thought you resigned."

They are all young people who love lively atmosphere. Whenever mining equipment is made, Li Xiaodong always watches and learns. Over time, he is also considered a half-radio enthusiast. Although he lacks practical experience and theoretical knowledge, his familiarity with various materials exceeds that of many amateurs. In the past, Hu Guangliang would specially let Li Xiaodong select the materials he needed.

"I really don't want to do this anymore, I just miss you all." Li Xiaodong grinned. The two chatted for a while, but an officer next to them seemed impatient.

"Xiaodong, everyone who uses mining machines knows that different types of variable capacitors have different performances. For example, the performance of small sealed variable capacitors is inferior to that of air dielectric ones, which is determined by their manufacturing principles." Hu Guangliang added, "It's not that I don't give you face today, but what you said violates scientific common sense. These materials were barely usable before, but not today. I'm going to return them now."

Li Xiaodong quickly stood in front of Hu Guangliang and said, "Practice makes perfect. Why don't we verify it ourselves?" His suggestion immediately won everyone's support.

"That's a good idea. We often use capacitors, but we've never tested their quality parameter, Q."

"Although Xiaodong has a low level of education, his understanding of ore mining machines is deeper than mine."

"Yes, we can tell which one has a higher Q value by testing it."

"Okay, let's give it a try." Hu Guangliang nodded in agreement. He was also curious about the Q value limit of small sealed capacitors.

"Wait a moment, I'll go get the testing tools." Li Xiaodong put down the basket, turned and walked towards Sister Niu.

"Sister Niu, this is what happened..." After listening to Li Xiaodong's explanation, Sister Niu, who was knitting a sweater, frowned.

"I don't understand those professional things. Please tell me what tools are needed for testing. Don't let these guys return the goods casually, otherwise it will be troublesome to reconcile the accounts at the end of the month." Sister Niu warned.

"Don't worry, with me here, they won't be able to return the goods, and they may even buy more." Li Xiaodong took the order and walked into the warehouse. Five minutes later, he came out holding a fist-sized copper coil, a frequency meter, and several lacquered copper wires.

Hu Guangliang has placed the capacitor on the table. Li Xiaodong came to the table and looked at everyone: "I connected the coil and the capacitor in series to form an LC circuit to measure the Q value of the coil. Because the coil is constant here, when measured in parallel with different fixed capacitors, the Q value will change accordingly, which indirectly reflects the performance of the variable capacitor."

"Does anyone have any objection to this method?" Li Xiaodong asked.

Hu Guangliang nodded: "No!"

Lao Bai nodded: "No!"

Others nodded: "No!"

Li Xiaodong quickly connected the coil and finally connected it to the frequency meter. Instantly, the dark blue screen of the frequency meter flashed with light. The line of numbers came into view, causing everyone to gasp in surprise.

"!"

"Oh my god, look, it's reached! It's much higher than the air variable capacitors used in military aircraft."

"Impossible, absolutely impossible, this is not in line with scientific principles!" Lao Bai's face was full of disbelief, and he suddenly looked up at Li Xiaodong.

"Did you do anything?"

Can't afford to lose?

Li Xiaodong frowned and was about to speak, but was interrupted by Hu Guangliang. "Lao Bai, you should know Xiaodong's character well. How could he play such a trick? Besides, whether the capacitors are sold today or not has nothing to do with him."

Lao Bai was speechless. But he was a man who would not give up until he reached the Yellow River. He picked up the frequency meter again to test it himself. Looking at the glaring, he had to accept the result.

"Brother Xiaodong, can you explain to me how this goes against science?" Everyone gathered around. It was unbelievable that an old variable capacitor could outperform the latest air variable capacitor.

Li Xiaodong smiled and picked up the capacitor. "We are all college students. We have taken physics classes and done a lot of experiments. We should know that there is a term in physics called error. Theoretically, the performance of air variable capacitors is better than that of sealed ones. However, in actual production, factors such as cleanliness, internal gaps, and oxidation degree may cause the finished product to deviate greatly from the ideal state."

"Air capacitors are new, so their technology is naturally not as mature as that of older products." He looked around at everyone, "So, this is completely in line with scientific logic."

---

In the 1960s, Tsinghua University did not accept students with special talents.

As one of the top universities in China, Tsinghua University is known as the "cradle of engineers."

There is even an atomic nuclear reactor experimental base on campus, and the students' knowledge level and practical ability are far beyond ordinary people.

Although Lao Bai always wears a military officer's coat and looks arrogant, he is actually a member of the physics department's research team and has participated in the research and development of major national projects. When he heard the word "error", he immediately understood the reason for the "unscientific" phenomenon.

However, he still had doubts in his mind.

How could a temporary worker have such insight?

Seeing that Lao Bai was dumbfounded, Hu Guangliang nudged him with his elbow. "Lao Bai, you misunderstood Xiao Dong. Apologize now."

Lao Bai seemed to be too embarrassed to do it, and was hesitant and coy.

After all, although this era is close to equality for everyone, there is still a slight gap between officers and ordinary people.

Li Xiaodong expects these partners to help him pay back Yi Zhonghai's money and naturally will not embarrass him.

"No need to apologize, this is just an academic discussion, and it's normal to have different opinions. I've been in the material store for a long time, and I've seen a lot, but my theoretical knowledge is indeed not as good as you future pillars."

Lao Bai felt relieved and looked at Li Xiaodong with gratitude.

This temporary worker does not seem to be incompetent.

Hu Guangliang glared at him and said, "Li Xiaodong, this is to show some mercy to you. Don't accuse others of tampering without evidence in the future."

"I see. You are stricter than me!" Lao Bai said with an awkward smile. "When the supply and marketing cooperative opens, I will treat Brother Donglai to a bottle of Beibingyang."

...

After the debate, Hu Guangliang began to assemble the mineral receiver.

The assembly process is not complicated. You only need to make a few holes in the wooden board, fix the line connector, air coil and other components, and then connect them through a high-resistance secondary conversion impedance, and then connect a 2000pF capacitor.

The key challenge is how to install the chalcocite to achieve detection, which is crucial for the crystal receiver to clearly receive the station.

Hu Guangliang carefully drilled holes in the wooden board, installed the chalcocite, and connected it with wires.

"Is it done?" Lao Bai asked anxiously.

"I'm not sure, but I have a strong feeling that we should be able to receive the Beijing Radio Station this time." Hu Guangliang wiped the sweat from his forehead.

He had tried his best just now. If it still didn't work, he might have to accept Lao Bai's suggestion and buy Ye Zi a radio. At most, he could prepare some extra batteries for her to carry with her.

At this point, the team members had already connected the more than one-meter-long antenna to the mineral receiver.

"Well, practice is the only criterion for testing truth. Success or failure depends on this one."

Hu Guangliang pressed the button and the mineral receiver made a "squeaking" noise.

Hu Guangliang looked solemn and slowly adjusted the buttons.

Squeak...squeak...squeak...

Suddenly, a melodious song came from the mineral receiver.

"Grow up quickly, little pine tree, tender green buds hang on the branches, and the golden sunshine warms you."

The music started and everyone became excited.

With the sound, there is no doubt that the crystal receiver is successfully made.

Lao Bai gave a thumbs up and said, "Guangliang, I'm impressed. No one else can make such a clear mineral receiver except you."

Hu Guangliang also breathed a sigh of relief.

Only Li Xiaodong looked calm, standing with his arms folded.

Just now he clearly saw that Hu Guangliang's hands were shaking slightly when he was installing the ore, causing the position of the ore to shift slightly.

How could it be so smooth? Is there an "unscientific" factor?

"Let's go. Brother Guangliang has won the first battle today. I will treat everyone to a drink of Arctic Ocean to celebrate."

Just as Lao Bai was about to put away the crystal receiver, the radio program ended.

"Okay, that's it for 'Little Pine Tree' sung by the Youth Choir. Next we'll play the opera 'Red Guards of Honghu Lake'."

[RECREATION]22

Shenyang Radio Station!!

Lao Bai's hand was suspended in the air, with his fingertips only 0.01 centimeters away from the ore machine.

Hu Guangliang's face instantly turned as dark as ostrich ink.

The college students looked at each other with astonishment in their eyes.

"Why did the originally agreed Beijing Radio Station become the Shenyang Radio Station?"

"The ore must have been placed in the wrong location."

"Keep your voice down. Old Hu is not in a good mood right now."

Hu Guangliang was indeed in a bad mood.