Before we dive into the button combinations, let’s understand why you might need to perform service work on the AT-5555N II.
The Problem: Local stations are S-9 on your friend’s radio, but S-3 on yours. The audio is quiet.
The Work:
When doing anytone at5555n ii service menu work, avoid these fatal mistakes: anytone at5555n ii service menu work
Once inside, you will see parameters labeled P-XX. Here is a breakdown of the most critical ones you will likely need to modify. Note: Firmware versions vary slightly, but these are standard on the V4/V5 hardware.
| Menu Item | Function | Typical Range | Why You Need It | | :--- | :--- | :--- | :--- | | P-01 | VCO Lock Voltage (Band A) | 0-255 | Diagnose Tx/Rx dropouts. Should be stable. | | P-07 | AM Carrier (Deadkey) Power | 0-255 | Most common adjustment. Raise/lower DK wattage. | | P-08 | AM High Power (Full modulation) | 0-255 | Sets max AM PEP. Balance with P-07 for 1:4 ratio. | | P-09 | LSB Transmit Power | 0-255 | Adjust SSB output on Lower Sideband. | | P-10 | USB Transmit Power | 0-255 | Adjust SSB output on Upper Sideband. | | P-11 | FM Transmit Power | 0-255 | Sets FM carrier power. | | P-15 | S-Meter Zero (Squelch threshold) | 0-255 | Calibrates S-meter to show "S-0" correctly. | | P-16 | S-Meter Full Scale (S-9 + 60dB) | 0-255 | Sets high end of signal meter. | | P-32 | PLL Reference Frequency (Master Oscillator) | 0-255 | The holy grail. Corrects frequency drift on TX/RX. | | P-45 | AM Modulation Depth | 0-255 | Sets percentage of modulation (avoid 100%+ to retain clarity). | | P-58 | Mic Gain Pre-Amp (SSB/AM) | 0-255 | Boosts internal mic preamp if external audio is weak. |
If you want, I can convert this into a printable one-page technician checklist, a step-by-step guided calibration for a specific parameter (TX power, PA bias, or VCO trim), or a troubleshooting flowchart — tell me which. Before we dive into the button combinations, let’s
The AnyTone AT-5555N II includes a hidden service menu used by technicians for calibration, diagnostics, and programming checks. This article documents how to safely access the service menu, common menu items and their meanings, recommended procedures, and safety precautions. Only qualified technicians should perform service-menu operations; incorrect settings can render the radio inoperable or violate regulatory rules.
If you have the proper test equipment, follow this workflow:
Honestly? Only if you have the gear.
If you don't own a frequency counter or a Bird wattmeter, do not open the service menu. Instead, send the radio to a reputable tech. The cost of calibration ($50-$80) is far less than the cost of a new AT-5555N II ($300+).
However, if you are a ham with a bench, the service menu turns the AT-5555N II from a "good off-the-shelf radio" into a precision instrument.