Movement record · Switzerland
ETA/Unitas 6497
Partially verifiedA large, simple bridge-type hand-wound calibre originally supplied as a pocket-watch movement and later widely re-used, undecorated or finished to order, in mechanical wristwatches valued for their visible, easily serviced construction.
Technical specifications
- Diameter
- 36.6 mm (16½ lignes)
- Height
- Approx. 4.5 mm
- Jewels
- 17 (base); higher-jewel and decorated versions exist
- Frequency
- 18,000 vph (2.5 Hz), later variants at 28,800 vph
- Power reserve
- Approx. 46 hours
- Winding
- Hand wind
- Setting
- Pull-out crown, sweep or small seconds depending on variant
- Escapement
- Swiss lever
- Balance
- Glucydur-type balance with Nivarox hairspring on later production
- Complications
- Subsidiary seconds (6497); centre seconds on the related 6498 layout varies by source
Identification features
- Large 36.6 mm plate size unusual in a wristwatch
- ETA or Unitas signature on the bridge of unbranded examples
- Small seconds at 9 o'clock (the 6498 places it at 6)
- Large balance under a cock; simple, robust going train
- Diameter about 36.6 mm
Known variants
- 6497-1 (small seconds)
- 6498-1 (centre seconds arrangement)
- 6497-1 and 6497-2 (hacking)
- 6498 with seconds at 6
- Many decorated or skeletonised finishes
Servicing notes
Straightforward to service given its size and simple bridge layout; parts remain widely available.
General guidance only. Antique movements should be serviced by a qualified watchmaker.
Historical significance
Large (16½-ligne) manual-wind movement designed originally for pocket watches in the 1950s and now widely used in oversized wristwatches because its size gives a broad, easily decorated bridge layout.
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- ETA technical documentation
- Trade literature on base-calibre re-use
Where sources disagree, the disagreement is stated rather than resolved silently.