♂?，，

  Old Xu stared at the wooden box in his hand with a look of astonishment.

  At first, he didn't notice it and just thought the wooden box was old and fragrant. But when he opened the lid, he found that this was actually a radio. When he looked at the structure inside more clearly, he was even more surprised to find that it was a crystal radio.

  Lin Changming saw Old Xu's surprised face and was also puzzled, so he asked:

  "Old Xue, isn't this thing ridiculous? My kid has been insisting that he made it himself. Isn't that a joke? If he could really make radios, wouldn't the radio factory have gone bankrupt?"

  "This isn't mine." Old Xu shook his head at him, then said with a serious tone, "Changming, you really need to change your violent temper. Xiaohong may look like he doesn't like to talk, but he's actually very clever. You care too little about the child, as a father, yet you're so careless and don't understand your own son at all..."

  When Lin Changming heard Old Xu's words, he nodded frequently, with a look of being taught. Upon careful consideration, what Old Xu said was not wrong, he indeed cared too little for his own son, and there was no woman at home to take care of things. In other families, children of this age were considered precious jewels by their parents, who would be afraid of exhausting them with tasks, while in his own family, some trivial matters still had to be done by his several-year-old son, thinking of which made him feel somewhat ashamed.

  At the same time, he was shocked beyond words, never having imagined that Old Xu would place such importance on his own son.

  "Could it be that this radio was really made by Xiao Hong himself?"

  Lin Changming looked at his innocent-looking son, feeling extremely complicated inside, shocked, regretful, happy, and relieved...

  "Lin Hong, let's go, we'll go to the room and see how this mining machine performs."

  Old Xu suddenly became interested, he had asked Lin Hong several times about the progress of the mining machine before, but was always vaguely fooled by the other party, who kept pushing it away saying it wasn't finished yet and was being improved, without realizing that the other party had already started treating the "mining machine" as a work of art.

  Old Xu carefully carried the crystal radio in his hands towards his room, with a hint of expectation in his heart. In his mind, he had always looked at Lin Hong differently, thinking that this child was talented. Now looking at the work he did, it's indeed not bad. Moreover, just now he also roughly scanned it, and the design of this crystal radio is very thoughtful in many aspects, such as the design of the switch and headphone jack, which can be called classic, taking into account both safety and convenience.

  Lao Sun also followed behind with a smug face, muttering in a low voice: "Heh heh, I knew this kid was cunning. Otherwise, would I have taken him as an apprentice?"

  He said this without batting an eyelid, not feeling the slightest bit guilty about being a master who didn't quite live up to his title. To be sure, ever since he last taught Lin Hong the Three-Body Stance, he hadn't taught him anything else; occasionally running into him was just a brief reminder of the stance's key points.

  Old Xu put the wooden box on his workbench and began to take out the external meter to test some important parameters inside this mineral radio.

  To measure the quality of a radio, first consider the variable capacitor and coil Q value. This is an important parameter for measuring inductive products. The higher the Q value, the smaller the loss and the higher the efficiency. Next are the detector's forward voltage drop and sensitivity, as well as parameters related to headphones and antennas.

  Old Xu put on his old glasses and used a multimeter to measure for half a day, finally sitting up straight with his body, muttering to himself all the time.

  Old Sun heard his old friend keep saying things like "What a wonderful idea...such a clever design...unbelievable..."

  He curled his lip and interjected: "It's just a broken radio, what's the big deal?"

  Old Xu looked at him with some speechlessness, and finally opened his mouth: "The stone radio is simple, but it's really difficult to do well. The parameters of this radio have reached the limit of the stone radio."

  Others may not understand, but Old Xu is very clear in his heart. Making a mineral radio is basically an introductory course for electronic professional students, and he also spent a lot of thought researching this back then, the finished product's performance parameters are far inferior to this one.

  Lao Xutou also didn't think that Lin Hong did it according to the manual, because he had basically read all the books and magazines here, and none of them recorded such a method for making mineral machines.

  At that time, when he was studying in the Soviet Union, he also participated in such a competition. At that time, experts from China and the Soviet Union worked hard to make dozens of various mineral machines. Old Xu's mineral machine at that time won third place, but compared with this one, it is much inferior in appearance, component layout, and key parameters.

  Old Xu turned his head and asked Lin Hong: "How's the reception effect?"

  "Nothing in particular." Lin Hong replied.

  Old Xu heard this and couldn't help but feel a little strange. Logically speaking, this ore machine shouldn't be performing that poorly.

  "What antenna? What kind of antenna?"

  Lin Changming hastily said: "The one in the yard is hanging on the Zhang book, it's strange and weird, like a fish skeleton."

  Old Xu ignored him and looked at Lin Hong instead.

  Lin Hongru replied: "I made some improvements on the basis of the eight wooden antennas, but the listening effect was still not ideal and could only receive seven or eight radio stations."

  Old Xu didn't care about that much, directly connecting the radar antenna he designed to the rock machine, then turned on the radio's switch button.

  Ten minutes later, Old Xu was completely speechless.

  "Such an effect, and you say it's ordinary?"

  He received many big and small radio stations, even one from a city in southern Soviet Union.

  This has already far exceeded the category of crystal radios. Ordinary crystal radios can receive one or two strong stations, and the number of radio stations just received has already exceeded ten. Although it has a lot to do with Old Xu's antenna, this is not the fundamental reason.

  Lin Hong actually said performance is just "average", Old Xu can only conclude that a newborn calf is not afraid of tigers.

  Lin Hong didn't know what the situation was like when the radio was in other people's hands, he just based it on his own ideas. He thought that if he couldn't receive certain shortwave stations, then the effect was only average. All along, he had been using Lao Xu's radio as a standard to demand of himself.

  This is simply a nearly perfect mineral radio!

  Old Xu held the wooden box in his hands, but his eyes were fixed on Lin Hong. His eyes showed an unusual sparkle. He thought to himself that Lin Hong was like an uncarved jade, only eight or nine years old, without any guidance from others, and yet he could create such a work just by self-study...

  "Heh heh, Old Xu, isn't my apprentice pretty good?" Old Sun saw the situation and became even more pleased with himself, immediately showing off. The apprentice is clever, and the master also gains some glory.

  Old Xu's head was stunned and said: "When did he become his apprentice?"

  =====

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