Once We Lived in Nanjing

Friday.

Ban Xia hummed a tune, spreading the schematics across the table.

The diagram provided by BG4MXH detailed the modification points for the GR3188 relay station and the Icom725 radio, and last night, BG4MXH patiently guided her as if teaching kindergartners to recognize Chinese Pinyin. He repeated each sentence three times, and if it was still unclear, he'd repeat it three more times. With a blend of emotion and reason, he gently persuaded and thoroughly clarified, and the girl studied seriously. She took down the English-Chinese dictionary that her teacher had left her but she had shelved, and now she flipped through it whenever she had time.

In the late autumn afternoon, the weather was unusually crisp, with bird droppings covering the windowsill and golden fallen leaves carpeting the road.

As the temperature dropped day by day, when Ban Xia saw more and more squirrels in the neighborhood, she knew another winter was coming. However, Nanjing's winters didn't bring snow, and the animals hadn't had time to adapt to the climatic changes. They were still busy preparing for winter storage. Their dense winter fur, developed over millions of years of evolution, would make them too hot to sleep this winter.

Nanjing used to have snow, but from a certain year on, it stopped.

"COR OUT... The Motorola receiver's COR OUT of the relay station connects to the radio's PTT."

"RX AUDIO, where's the RX AUDIO interface again? Here... it connects to the MIC interface of the radio."

"Last is GND."

Wearing a tank top and shorts, Ban Xia tied her hair in a ponytail and sat cross-legged on a chair, with a table in front covered with electronic components.

She unplugged the hand mic from the Icom725 radio and observed it closely with curiosity.

This was the first time Ban Xia had ever unplugged this thing. The hand mic, also from Icom, was weighty, solidly built, and fit perfectly in the palm. The small numeric keypad on it had become blurred from use.

The plug of the hand mic was cylindrical. In layman's terms, this cylindrical plug was known as an aviation plug, officially called "aviation connector." It was an eight-hole plug with a small hole in the center and the other holes evenly distributed around it. Its socket was located at the bottom left corner of the radio control panel, corresponding to the plug and containing eight slender metal pins.

Each pin had a different function, and to connect the radio and the relay station, the first link had to start here.

The hand mic was the microphone—people spoke into it, so generally, the information was input into the radio from the hand mic's port.

This was the mouth of the radio.

The receiver of the relay station had to be plugged into the mouth of the radio.

And the transmitter of the relay station had to be inserted from the back of the radio.

It was a radio threesome.

But Bai Zhen dismissed this with a wave of his hand: No, it wasn't a radio threesome, how could it be so promiscuous? The transmitter of the relay station wasn't responsible for output; it was the receiver.

Finally, a linkage was formed where the receiver could pass information to the radio, and the radio could pass information to the transmitter.

So it was a radio centipede!

To figure out where each of the eight pins in the socket led, Bai Zhen and Wang Ning searched the entire internet and found the user manual for the Icom725 amateur radio.

"BG4MSR, look carefully at the hand mic's connector. These eight pins are numbered counterclockwise from 1 to 8, with the middle one being number 8. We need three connections: one for PTT, one for MIC, and one for GND," Bai Yang explained meticulously, "MIC is pin 1, PTT is pin 5, GND is pins 6 and 7, but we'll use pin 7. Did you get all that? OVER."

No one spoke in the channel.

"Did you get all that? OVER."

Still no one spoke in the channel.

"Miss? BG4MSR? Are you there? Why aren't you talking? OVER."

In his urgency, Bai Yang rattled Ban Xia, who hurriedly reconnected her hand mic and said impatiently:

"Aren't you the one who asked me to unplug the hand mic? How would I talk then?"

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Ban Xia powered up her soldering iron.

To use a soldering iron, one needs rosin. Ban Xia had searched the entire computer city without success until Bai Zhen suggested she raid a music store, where she indeed found some.

Wang Ning reminded Ban Xia to be careful when using the soldering iron.

"Don't hold it by the iron tip."

Bai Zhen asked if there really were such foolish people? Holding a hot iron by the tip?

Wang Ning said of course there were. Plenty of people treated the soldering iron like a pen.

Ban Xia straightened a thin white wire from the relay station, then picked up the scissors, and with a "snap," she neatly cut off one end connected to the PCB.

The heads of the PCB fell to the ground, and Ban Xia peeled back the white rubber insulation of the wire to separate the red, black, and yellow thin wires.

These three wires needed to be connected to the hand mic port of the radio.

The red wire was COR OUT, corresponding to PTT.

The yellow wire was RX AUDIO, corresponding to MIC.

The black wire was GND, corresponding to GND.

However, the metal pins inside the 725 radio's port were tiny, and connecting wires to such slender pins was tricky; it was difficult to fix them together.

Therefore, Bai Zhen suggested Ban Xia find some thin copper wire, wrap it around the pins in a helical, spring-like fashion until it could slot onto the slender pins without falling off, then remove the coiled copper wire and solder it together with the electric wire.

This way, a simple homemade plug was created.

"These pins are too slender, hard to plug in," Ban Xia complained. "What if my hand shakes?"

"Do you have Parkinson's?"

"What's Parkinson's?"

"Parkinson's means half-paralyzed and constantly shaking."

"Really? That sounds interesting. I want to have Parkinson's, keep shaking non-stop."

Having soldered them all, Ban Xia connected the three wires from the relay station receiver to the corresponding pins in the radio's hand mic port, completing half of the work.