I started with a ship full of max-level veterans, and I'm just a complete noob.

The pointer is still dropping.

Eighty-five, eighty, the coating is collapsing faster than expected. In a few more seconds it will fall below the critical threshold and A02 will completely turn into a waste glass tube.

Lu Qinghe stopped looking at the pointer and started moving her right hand.

She unplugged the signal wire from the output terminal of the Jia-02 lamp. A spark flew from the copper plug, flashing briefly in the dim red glow of the filament on the tube casing before going out.

The spare socket for Jialingsan was about 30 centimeters to her left, and the filament preheating switch was a red lever with a spring reset.

She pushed the lever all the way down and simultaneously inserted the signal cable plug into the output terminal of the 03 series. A short, crisp sound was heard as the copper contact surfaces clicked together.

"Forty-five seconds."

Chen Zhiyuan had already started moving on the other side of the delay line.

He unscrewed the coaxial connector from the old adapter board and connected it to the new adapter corresponding to the output of the A03.

The threads need three and a half turns to engage. When he got to the third turn, his fingers slipped. He took a deep breath, squeezed them again, and tightened them to the third and a half turns, sealing the metal casing.

The oscilloscope screen still showed that white wall of noise, and the hissing sound from the speakers filled the wooden house.

Lu Qinghe looked at the micro-announcement of Jia Ling San.

The pointer started climbing from zero, but the speed was a little slower than the preheating curve she remembered. It was probably because the temperature was too low at night and the cathode substrate had not yet reached thermal equilibrium.

Thirty seconds later, the pointer reached 200 microamps.

Thirty-five seconds, two hundred and thirty.

Forty seconds, two hundred and fifty-two.

Forty-five seconds passed, and the pointer was still moving, from 255 to 260, finally stabilizing at 268 microamps.

Faced with a noise wall covering the entire shortwave band, the rare earth coating of the A03 did not collapse like that of the A02, and the transmission current was only seven microamps lower than the static nominal value.

"The pipe is alive."

Chen Zhiyuan peeked at the watch face from the other end of the delay line, his voice tinged with uncertainty.

"Will it work?"

"It works."

Lu Qinghe is already adjusting the receiver's intermediate frequency gain, trying to pull the saturated signal from the previous stage back into the linear range.

"But it's not a narrow pulse; the delay line can only suppress components near the main frequency, not completely."

Chen Zhiyuan returned to the adjustable capacitor and began fine-tuning it.

The principle of a delay line is to use phase difference to cancel out signals of a specific frequency.

It was more than enough to deal with the narrow pulse interference with a 15-second interval, but the current block of broadband white noise did not have a single dominant frequency. It was spread out from 3 MHz to 6 MHz, and the delay line could only catch the most concentrated part of the spectrum.

He slowed down the oscilloscope's time base to observe the spectral distribution of the noise wall.

The noise is not completely flat; there is a noticeable energy bulge around 4.5 MHz, about 200 kHz wide, and nearly twice as high as the sides.

"Center frequency 4.5 MHz".

He reported the reading to Lu Qinghe, while he was already adjusting the capacitor, pulling the cancellation frequency of the delay line from 3.8 MHz to 4.5 MHz.

The secondary capacitor was rotated down two notches from 14.2 picofarads to approximately 11.8 picofarads.

On the oscilloscope screen, a dent appeared in the middle of the white wall.

Although it is only less than halfway indented, the baseline at the indentation is already able to distinguish the outline of the directional signal.

"About 60% was cut."

Chen Zhiyuan estimated the depth and original amplitude of the indentation and wrote down the data in his notebook.

That's enough.

Lu Qinghe stared at the barely discernible signal in the depression and used a protractor to read the azimuth.

One hundred and forty-seven degrees.

The direction has not changed.

The source of the interference is still in the depression in the eastern section of the Camel Trail, which is completely consistent with the previous dozens of records.

But the center frequency of 4.5 MHz made her pause for a moment.

Previously, the transmission frequency of "three short, one long, and three short" had been around 3.8 MHz, with a maximum deviation of no more than 0.5 kHz.

The energy center of this wall of noise is 4.5 MHz, which is a full 700 kHz higher, and its power far exceeds the output capability of a small radio station.

"It's not that telegraph machine."

Lu Qinghe made this judgment very quickly, without any unnecessary embellishment.

Chen Zhiyuan looked up at her.

"You mean there's other equipment downstairs?"

"The power of a telegraph machine is at most a few tens of watts; it can't produce this kind of effect."

She tapped the pencil on the notebook, leaving a black dot.

"4.5 MHz, broadband continuous wave, requires at least several hundred watts of radio frequency power to saturate our preamplifier. There are high-power transmitting devices in the underground bunker, not communication equipment, but jamming equipment."

When Lao Zhou heard this, he turned around from the window, his face looking rather grim.

"Did they hide a jammer underneath?"

Lu Qinghe did not answer.

The answer is already on the oscilloscope screen.

She walked over to the radio, sat down, picked up the send button, and sent three messages to the command post in the most concise way possible.

First, the location of the interference source remains unchanged, still in its original position on the eastern section of the Camel Trail.

Second, the interference is high-power broadband white noise with a center frequency of 4.5 MHz. It is not caused by the original transmitter, and there may be fixed high-power transmitting equipment in the underground fortification.

Third, A02 is scrapped and has been replaced by A03, which can be used for no more than 20 minutes.

After sending the message, she released the button, returned to the receiver, picked up the alarm clock, placed it next to the panel, aligned the second hand with the twelve o'clock position, and started timing.

twenty minutes.

From this moment on, the thin coating of Jialingsan is racing against time.

The coating is thinner than both the Alpha 01 and Alpha 02, and has a lower heat capacity. It can withstand impacts for a short time, but its heat dissipation cannot keep up with the cumulative effect.

Twenty minutes is the safety limit; beyond this time, the coating temperature will enter the irreversible ablation range.

"Keep memorizing the directions."

She said something to Chen Zhiyuan, her attention focused on the oscilloscope and the microammeter.

Two hundred and sixty-eight microamps, the pointer did not move.

The first three minutes were stable.

In the fourth minute, the noise wall on the oscilloscope screen suddenly increased by about 15%, as if the other party had increased the power level again.

The receiver preamplifier gain is further compressed, and the signal profile at the delay line recess becomes more blurred.

Chen Zhiyuan paused for a moment while adjusting the capacitor.

"The power has been increased."

"Can directions still be read?"

He leaned closer to the oscilloscope for three seconds and made two marks on his notebook.

"We can barely make a judgment, but the accuracy has dropped to about two degrees, which is half as bad as before."

"Two times is enough."

Lu Qinghe wrote down the location data for the fourth minute in his notebook, and marked the accuracy degradation and power change next to it.

The microammeter of the Jialing 3 showed its first fluctuation in the fifth minute, dropping from 268 to 265, and then returning to 267 two seconds later.

It's not an avalanche; it's the increased surface temperature of the coating that causes a slight adjustment in the thermionic emission efficiency.

In the sixth minute, the score was 267.

Seventh minute, 266.

It loses one microamp per minute; this is the coating consuming itself.

Old Zhou squatted by the radio, waiting for a reply from the command post. Finally, in the eighth minute, he received an urgent telegram.

After he finished copying the document, he handed it to Chen Zhiyuan, his expression somewhat complicated.

Chen Zhiyuan glanced at the contents and read them aloud.

"The vanguard of the first company has reached 200 meters outside the entrance and encountered barbed wire and concrete slabs. It has been confirmed that there are underground fortifications, and the engineers are dealing with the obstacles."

"How long will it take to get in?"

Lu Qinghe asked, her eyes never leaving the micro-announcement.

"He didn't say."

265 microamps, 9th minute.

Ten minutes, 264.

The noise wall's power was pushed up again, almost completely filling the indentation created by the delay line on the oscilloscope screen, reducing the readability of the azimuth data to its limit.

Chen Zhiyuan adjusted the capacitor by half a notch, and the dent reappeared, but it was much shallower than before.

"He's increasing his bets."

For the first time, Chen Zhiyuan's voice betrayed anxiety.

"He knew we were still watching him and wanted to drown out the last bit of signal."

In the twelfth minute, 262 microamps.

The numbers on the alarm clock made Lu Qinghe's back tense up a little, but her hand still held the pencil steadily, recording once per minute.

Fourteen minutes, 260 microamps.

The last readable record of the azimuth data is 146 degrees.

The deviation from the previous measurement was within the measurement error range, and the target did not move.

Fifteen minutes, 259 microamps.

The noise wall amplitude increased again, the delay line depression was completely filled, and the orientation could no longer be read directly from the screen.

Sixteen minutes, 257 microamps.

Seventeen minutes, 255 microamps.

The coating temperature is rising rapidly, and the slope of the decay curve is becoming steeper.

Eighteenth minute, 252 microamps.

The alarm clock shows two minutes left.

Lu Qinghe had already moved his right hand from the pencil to the filament switch of the Jialingsan tube, preparing to cut off the power at the moment the countdown reached zero and save the tube.

At that moment, a call signal from the command post came through the radio loudspeaker.

After Old Zhou finished copying the notes, his hand trembled slightly as he handed them over.

The note contained very little information.

The engineers have blown open the top of the bunker. We need to use a direction finder to confirm whether the interference source is still in a fixed position or is being moved. We require a response within five minutes.

Lu Qinghe watched the numbers on the alarm clock jump from two minutes to one minute and fifty-nine seconds, then shifted her gaze to the hand on the microammeter that was slowly tilting to the left.