We Live In Nanjing

  Chapter 75 Radio

  Friday.

   Banxia hummed a song and spread out the drawings on the table.

The drawings given by BG4MXH explain in detail the key points of modification of GR3188 repeater and Icom725. Last night, BG4MXH was as patient and guided slowly as teaching kindergarten children to recognize Chinese Pinyin, allowing Banxia to understand the role of each interface. , Repeat one sentence three times, and repeat three times if you don’t understand it, move it with affection, know it with reason, seduce it with good faith, tempt it and wipe it out. The girl is also very serious in learning, leaving the teacher behind but shelving it. I took down this English-Chinese dictionary and turned it over if there was nothing to do.

  In the late autumn afternoon, the weather is rarely dry, with bird droppings on the windowsill and golden leaves on the road.

The temperature is getting colder day by day. When the girl sees more and more squirrels in the community, she knows that another winter is coming, but winter in Nanjing is not snowing, and the little animals will have time to adapt to climate change in the future. They are still preparing for storage for the winter. The dense winter fur that these little rodents have evolved over millions of years will make them too hot to sleep in this winter.

  It used to snow in Nanjing, but from a certain year onwards, it will not snow anymore.

  "COROUT...The Motorola receiver COROUT of the repeater is connected to the PTT of the radio."

   "RXAUDIO, where are the RXAUDIO interfaces? Here...it connects to the MIC interface of the radio."

   "The last is GND."

  Banxia is wearing a vest and shorts, with her hair tied into a ponytail, sitting cross-legged on a chair, and the table in front of her is full of electronic parts.

  She pulled out the hand microphone of the Icom725 radio station, and curiously leaned in front of her eyes to observe carefully.

This is the first time that Pinellia has pulled out this thing. It is also the Icom hand microphone, which is the same brand as the radio station. It is heavy and thick. It holds exactly the size of a palm. I don’t know how long it took. There is a small numeric keypad, and the numbers are blurred.

The plug of the hand microphone is cylindrical. In layman's terms, this cylindrical plug is called an aviation plug. The full name is "aviation plug". It is an eight-hole plug with a small hole in the center and other small holes evenly distributed on the outside. , And its socket is in the lower left corner of the radio operating panel, corresponding to the plug, and there are eight slender metal pins in the socket.

  Each pin has a different function and function. If Pinellia wants to connect the radio and the relay together, the first link must go from here.

  Hand microphone is a microphone. It is a microphone. People hold the hand microphone and speak. So usually, the information is input into the radio station from the socket of the hand microphone.

  This is the mouth of the radio station.

  The receiver of the repeater station will be inserted into the mouth of the radio station.

  As for the transmitter of the repeater station, it must enter the station later.

   is simply radio 3P.

   But Bai Zhen waved his hand: No, it’s not 3P on the radio, how could it be so licentious? The transmitter of the repeater is not responsible for output, it is the receiver.

  Finally, a link is formed through which the receiver can transmit information to the radio station and the radio station can transmit information to the transmitter.

  So this is Radio Centipede!

  In order to figure out where the eight pins in the socket lead to, Bai Zhen and Wang Ning searched the entire network and found the manual for the Icom725 amateur radio station.

"BG4MSR, look carefully at the interface of the hand microphone. The eight pins are numbered counterclockwise from 1 to 8, and the middle one is number 8. There are three interfaces we need, one is PTT, one is MIC, and one It's GND." Bai Yang explained carefully, "MIC is pin 1, PTT is pin 5, GND is pin 6 and 7, we are going to use pin 7, do you hear clearly? OVER."

  No one speaks in the channel.

   "Did you hear clearly? OVER."

  No one speaks yet in the channel.

  "Miss? BG4MSR? Are you there? Why don't you speak? OVER."

  Bai Yang urged Pinellia into a hurry, and the latter had to plug the microphone back in, and said angrily:

  "Didn't you let me pull my hand microphone! How do I talk?"

  ·

  ·

  ·

  Pan Xia energizes the soldering iron.

  I need rosin with an electric soldering iron. Banxia searched the Computer City and couldn't find it. Bai Zhen had a clever move and asked her to rob the musical instrument shop, and she found it.

  Wang Ning urged Pinellia ternata to be safe with an electric soldering iron.

  Do not hold your hands on the iron core.

  Bai Zhen said there would be such a stupid person? Holding it on the core of the soldering iron?

  Wang Ning said, why is there no more? Most of them use soldering irons as pens.

  Banxia straightened the thin white wire on the repeater, then picked up the scissors, clicked, and cut off one end of the PCB board neatly.

  The head of the PCB board is on the ground, and Pinellia peels off the white rubber sheath of the wire to separate three thin wires, red, black and yellow.

  These three lines must be connected to the microphone jack of the radio.

  The red line is COROUT, which corresponds to PTT.

  The yellow line is RXAUDIO, corresponding to MIC.

  The black wire is GND, which corresponds to GND.

  There are metal pins in the socket of the 725 radio. The wires are connected to the thin pins.

So Bai Zhen suggested that Pinellia should find the thin copper wire, first wind the thin copper wire around the pin one by one, winding it into a spring-like slender spiral, and make sure that it can fit on the thin pin without falling off. Then pull out the spiral copper wire and solder it with the wire.

  In this way, a simple self-made plug is obtained.

   "This needle is too thin to be inserted." Banxia vomited, "What should I do if my hands are shaking?"

   "Do you have Parkinson?"

   "What is Parkinson?"

   "Parkinson is paralysed and trembling all the time."

   "Really? It sounds so interesting. I want to have Parkinson too. I keep shaking and shaking all the time."

  Banxia solder them all, connect the three wires of the repeater receiver to the corresponding pins of the radio microphone jack, and half of the work is done.

  Next is the other half.

  The other half starts with the **** of the radio station.

  There are two ports on its butt.

   "Two jacks! ACC1 and ACC2!"

   "Yes, there are two jacks for turning two and five. As I told you, I need to use the ACC1 interface! Pay attention to the metal nameplate on the back of the radio. Which one is ACC1 is marked on it."

   "Right."

   "Yes, the one on the right."

  "This is a multi-hole interface, there are so many holes in this socket... one, two, three, four, five, six, seven, eight... eight small holes!"

  In order to find out the function and function of these eight small holes, Bai Zhen and Wang Ning searched the whole network again. The detailed information of Icom725 is really hard to find.

There are quite a few ports on the back of the Icom725 radio. The most striking thing is the two circular ACC sockets in the center. These are two multi-hole sockets. Each socket has eight spindle-shaped holes, which are distributed like a chrysanthemum bloom. The socket of the hand microphone is just the opposite. The socket of the hand microphone is a pin, which is the input port for information, while the ACC socket is a hole, which is the output port for data. The hole should be better to deal with, and you can insert it directly with a thin copper wire.

  But how to insert and which ones are the key.

  "Well... the SQLOUT of the radio is connected to the PTT of the repeater transmitter."

  "EXSPEAKER is connected to the MIC of the transmitter."

   "The last is GND."

  Banxia still remembers BG4MXH's advice.

  She pulled out a thin white wire and straightened it out—this kind of cable with PCB board at both ends has only one in a repeater, and it is used to connect the transmitter and the receiver.

  The connection line of GR3188 relay itself has just been cut by Pinellia.

  The line is plugging one end into the receiver and one end into the microphone jack of Icom725.

  So Pinellia found a connection cable from other relays of the same model, and cut off one end neatly, and separated three thin red, yellow and black wires from under the white rubber.

  Three thin wires are each welded with a long copper wire.

   "Which hole is SQLOUT?"

   "Hole No. 6."

   Carefully insert the three copper wires into the bottom of the radio station.

  Let this white cable plug one end into the bottom of the radio station and the other end into the relay transmitter.

  At this point, Radio Centipede is done.

  This set of programs has been successfully tested nine times by Wang Ning, Bai Zhen and others yesterday.

  But it's not over yet.

  There is another important component—antenna.

  Wang Ning and Bai Zhen thought about the antenna for a long time. To be honest, most of the antennas are bought these days. The manufacturer has set the parameters for you, and you can use it after you install it.

  But in the era of Banxia, ​​there was no Taobao or JD. Online shopping was impossible. If you want to get an antenna, the easiest way is to do it yourself.

  But the two old guys, Wang Ning and Bai Zhen, haven’t made antennas for many years. They don’t have this ability, but if they have the ready-made ones, why do they do it themselves? What's wrong with being a lazy dog? So swords and guns entered Kuma and released Nanshan.

  "How do you do the antenna? Do it yourself?" Wang Ning asked.

  "What else can I do if I do it myself?" Bai Zhen said, "Let's do it ourselves and try the effect. If it works, then teach her to do it."

  "What about the impedance standing wave?" Wang Ning asked, "She should not be able to measure it."

   "Let's make do with it, one of them is almost the same, it's not bad." Bai Zhen shook his head, "As far as the electromagnetic environment of her time was, the whole world could hear it."

  In theory, all conductors can be antennas.

  Only the effect is different.

  So to make an antenna, you can take materials from anywhere, such as drying racks, golden hoop rods, celestial circle, hoop curse, purple golden bowl, nine-tooth nail rake, Fangtian painting halberd, Qinglong Yanyue knife, as long as you can get it, there is nothing that can't be made into an antenna.

  Wang Ning and Bai Zhen chose to use coaxial cables.

   "Coaxial cable! Use coaxial cable, pretty good things, everywhere in the city, TV cables, network cables will do."

  "It's better to find 75-7, 75-5 is fine too!"

Coaxial cable is easier to find and has better effect than Qinglong Yanyuedao. It is often used as an antenna feeder. In fact, it can also be used as an antenna. The structure of coaxial cable is simple. It has a two-layer structure. The center is a metal core and core. There is also a fine metal mesh shielding layer outside the wire. The core wire and the shielding mesh are filled with insulating material, and the outermost layer is a rubber sheath.

  So the cross section of the coaxial cable is similar to that of a gun target, with a solid circle in the center and a ring on the outside.

  To make the coaxial cable into an antenna, the most important thing is to remove the metal shielding layer.

The shielding layer is like a Faraday cage. The reason why the anti-interference ability of the coaxial cable is stronger than that of the ordinary twisted pair is because of the existence of this shielding network, which can not only isolate external interference, but also prevent the electromagnetic waves generated inside the cable from radiating outward Divergence, so peel off this layer of skin so that the electric wave can spread out.

  "144MHZ, how long is it likely to stay?" Wang Ning asked.

  Bai Zhen stared at the black cables piled in a circle on the floor, pondered for a few seconds, and quickly mentally calculated in his head.

   "About 0.5 meters."

  The two people used a ruler to measure the length of 0.5 meters at the end of the coaxial cable, and then cut a circle with a small knife ring at the position of 0.5 meters.

  This is a massive circumcision, the foreskin alone is half a meter long.

  They stripped off the 0.5-meter-long slender foreskin, revealing the inner silver metal shielding net.

Wang Ning and Bai Zhen squatted on the floor, slowly rubbing the metal shielding net with their hands, using skillful techniques to loosen the shielding net woven with soft thin metal threads, and then pull them back little by little, like turning clothes. Cover the rubber sheath of the coaxial cable like a sleeve.

  After finishing the set, the simple entry-level 144MHZ antenna is basically completed.

  This coaxial cable is both a feeder and an antenna. The stripped part is the antenna responsible for radiating radio waves, and the unstriped part is the feeder for signal transmission.

It's that simple.

  Finally, Wang Ning used the standing wave meter to make fine adjustments.

The two carried out nine experiments with this antenna yesterday. The soft and collapsed coaxial cable could not be braced by itself, so Wang Ning tied it to a wooden mop stick. He held up two mops and leaned out the window. As if about to take off at any time, the owners passing by in the community were scared to the police.

  In Nanjing in 2019, in the Meihuashanzhuang community where power switches and electric vehicles are everywhere, these two seemingly simple whip antennas still stubbornly supported the scolding of Wang Ning and Bai Zhen.

   "Lao Bai, are you **** good? My waist is going to be broken. I told you that you have to compensate for my medical expenses. Five hundred yuan can't be less."

  "If you fly down, I will give it to you. I promise to burn it to you. It's a lot of money."

  "Fuck you, come up if you have the ability, come up and try."

   "If you have the ability, come down!"

   "You come up!"

   "You come down!"

  Banxia tied the prepared coaxial cable antenna to the stick, and BG4MXH especially urged her to use an insulator.

   There are two antennas, one for the transmitter and one for the receiver. The girl took a lot of effort to stick them out of the attic skylight and stand on the roof.

  144MHZ is the UV band, or to be precise, the VHF band. Electromagnetic waves propagate within the line of sight, so the higher the antenna is, the better.

   Pinellia asked how far it can pass?

  Wang Ning shrugged, he couldn't tell.

  UV waves are used for short-distance communication in conventional concepts, but nothing is fixed, there are exceptions to everything, as long as the conditions are right, the UV band can also be directly connected for hundreds of kilometers.

  Bai Zhen said that Nanjing in the last days was empty, the electromagnetic environment must be very, very quiet, and the signal-to-noise ratio of Telecom would be very good.

  Wang Ning said that a world with only one person really saves trouble, and relaying even saves Asian voices. Anyway, you are the only one who speaks.

  That night, the girl fully charged the mobile station.

   Baofeng UV9R waterproof version.

She followed Bai Zhen and Wang Ning’s instructions to find waterproof handstands. Banxia found a total of 18 well-preserved waterproof handstands on Zhujiang Road. Motorola and Yaesu, all the big names have lost the battle. In the end, only a very large stock. The Baofeng UV9R still works normally.

  Open the Icom725 radio station.

  Open GR3188 analog relay.

  Banxia took a deep breath, and she was busy with it for a whole week. Success or failure depends on this.

  Gently turn the switch **** on the top of the hand table, and the LCD screen lights up.

  In a night with a shining starry sky, the girl left the room and climbed to the attic, sat on the roof, and told BG4MXH about the stars she saw.

  (End of this chapter)