A common complaint with some AT-5555N II units is an elevated noise floor (e.g., an S5-S7 reading with no antenna connected). A popular workaround is to adjust the service menu:
However, beneath the surface of its user-friendly LCD display and multi-function buttons lies a hidden layer of calibration: .
Press and hold the button and the CLARIFIER knob simultaneously. While holding them down, turn the radio ON .
If done correctly, the radio will enter Service Mode, giving you access to the hidden parameters. anytone at-5555n ii service menu
Once the main shift is corrected, use the bfC (BFO) setting for final precision. This approach preserves your fr (frequency range) settings.
If you need to troubleshoot a specific parameter or want to look up a precise factory value alignment step, please let me know: Your current (displayed at power-up)
| Parameter (Channel) | Common Label | Function & Typical Adjustment | | :--- | :--- | :--- | | | RFG | RF Gain Calibration. A well-known adjustment for radios with high receive noise. The typical default is 86 . Increasing this value (e.g., to 105 ) can reduce the noise floor and make listening more pleasant but reduces the effective RF Gain control. | | CH-?? | TONE | Modulation Tone. There are separate parameters for AM, FM, USB, and LSB (e.g., AMTONE , FMTONE , USBTONE , LSBTONE ). Adjusting these changes the transmit audio's tonal balance. | | CH-?? | RXBPF | Receive Band-Pass Filter. The default is often 255 . Increasing this value can make the received audio sound "fuller" and less "thin" or "far away". | | CH-?? | TX Low Power (AM/FM/SSB) | Transmit Power on Low Setting. Adjusts the carrier or power output for the low power setting on each mode. | | CH-?? | TX High Power (AM/FM/SSB) | Transmit Power on High Setting. Adjusts the maximum power output for the high power setting. | | CH-?? | Frequency Calibration | Frequency Alignment. Sets the reference frequency for the entire radio, requiring precise measurement with a frequency counter. | | CH-?? | S-Meter Calibration (S9) | S-Meter Adjustment. Calibrates the point at which the meter reads S9 for a given signal strength. | | CH-?? | Modulation Limiter (AM) | AM Modulation Depth. Sets the maximum percentage of AM modulation, often to prevent flat-topping or overmodulation. | | CH-?? | ALC (Automatic Level Control) | Transmit Level Control. Adjusts the ALC to control the maximum transmit level across all modes. | A common complaint with some AT-5555N II units
Critical: Before making any changes, . If you change a parameter and don't have the original value, "you CANNOT change it back to how it was" without specialized test equipment. There is no "factory reset" for these hidden settings, so this manual backup is your only safety net.
Professional technicians typically use calibrated frequency counters and power meters when accessing these settings to ensure the device remains within manufacturer specifications. Technical Parameters in the Anytone AT-5555N II
Use a high-quality, regulated DC power supply to prevent noise and voltage spikes. While holding them down, turn the radio ON
To enter the service menu without a PC:
While holding those two buttons down, turn the volume/power knob clockwise to switch the radio on.