ETA F05.11A – Technical Communication

General Overview

• Caliber: ETA F05.11A

• Movement Type: 3‑hand quartz (hours, minutes, sweep seconds), available with a date window at 3 o’clock or 6 o’clock; 2‑hand variant also exists

• Ligne / Diameter: 10½''' (~23.3 mm)

• Movement Height: 2.50 mm; pinion height approximately 4.0 mm

Mechanical Specifications

• Jewels: None

• Hands Compatibility: Hour 1.20 mm, minute 0.70 mm, sweep-second 0.20 mm

• Stem: Typically uses S401‑2021 or ETA F05.111.405 (Tap 10)

Power Source and End‑Of‑Life (EOL)

• Battery: Silver-oxide 371 (1.55 V)

• Battery Life: Typically around 36 months

• EOL Indicator: Seconds hand jumps in 4-step intervals when voltage drops below approximately 1.30 V

Functionality and Variants

• Display: Standard version offers central seconds and semi-instant date at 3 o’clock; another variant places the date at 6 o’clock

• Variants:

  • Date at 3 o’clock (standard 3-hand + date)

  • Date at 6 o’clock (variant labeled F05.11A‑6)

  • 2-hand versions available with or without date

Electrical and Testing Details

• Power Consumption: Less than 10 µA at 1.55 V during operation

• Low Consumption Mode: Below 1.15 µA with external supply

• Stop-Lever Testing: In hand-setting position (stem pulled), consumption should be under 0.5 µA

• EOL Threshold: Between 1.30 V – 1.55 V, motor pulses increase from 8 to 16 steps per second

• Testing Conditions: All measurements should be performed at ambient temperatures between 20–25 °C

Serviceability and Compatibility

• Stem Compatibility: Compatible with ETA F05.111 stems (Tap 10)

• Hand Fitment: Standard hole sizes for hands — 1.20 mm (hour), 0.70 mm (minute), 0.20 mm (seconds)

• Component Mapping: Exploded views and lubrication charts are available in official technical documentation

Comparison with Related Calibers

• Shares the same base platform as ETA F05.105 and F05.115

• All variants maintain the same dimensions and basic performance features

• Updated models may include additional functions like HeavyDrive and PreciDrive

Summary Table

Technical Notes for Watchmakers

1. Battery Replacement: Use silver-oxide cell type 371. Watch for EOL jump indicator after fitting.

2. Stem Installation: Use Tap 10 stems for proper crown alignment.

3. Hands Installation: Standard diameters ensure compatibility with most generic or branded hand sets.

4. Service Guidelines: Follow ETA lubrication procedures. Test motor impulses using standard voltage and temperature.

5. Model Selection: Always verify date position and hand configuration before fitting to case or dial.

Conclusion

The ETA F05.11A is a robust and compact quartz movement widely used in Swiss-made and branded watches. With its versatile design, long battery life, and built-in EOL function, it’s a dependable choice for 3-hand and date watch configurations. Its compatibility with other F05 models and standardized components makes servicing straightforward and reliable.