Alarm B
1971 · Stainless
About the Alarm B
The Alarm B was made only in 1971, giving it a single catalog year in Hamilton's lineup. It runs on the caliber 642, a movement built around the relatively rare alarm complication, housed in a round stainless steel case. Hamilton produced several Alarm variants during this period, and the Alarm B is one of the more quietly scarce members of that family.
Finding one in good condition takes patience. The alarm mechanism adds complexity that many owners and even some watchmakers weren't equipped to service correctly, so examples with fully functional alarm trains are worth paying attention to. Applied indices on the dial are a detail to inspect carefully, since loose or missing markers are common on watches that have been worn regularly for fifty-plus years.
From the Catalog
Hamilton marketed the Alarm series on the practicality of having a wrist alarm available at any moment, and the stainless steel case positioned it as a durable, everyday-capable option. Exact period pricing for the Alarm B isn't confirmed in available records, but the alarm models generally sat at a premium over comparable time-only Hamilton pieces of the era.
Hamilton Catalog Images
1971
What to Look For
| Dial | Look closely at each applied index. Any that are separated, tilted, or missing will affect both appearance and value. Check for moisture damage, which often shows up as spotting or discoloration near the edges. |
| Crystal | Confirm the crystal is appropriate for the model. A replacement that doesn't sit flush can let dust and moisture in, which causes problems over time. |
| Movement | Test both the timekeeping function and the alarm separately. Dried oil creates enough friction to stop the caliber 642 even when the watch appears to wind and set normally. A watch that hasn't been serviced in years may feel fine to wind but not run reliably. |
| Case | The stainless steel case should show wear consistent with its age. Inspect the lugs for thinning from over-polishing, and check that the case back seats properly, as these can be tricky to open and reseat without damage to the threads or gasket groove. |
| Crown | The Alarm B typically uses two crowns, one for timekeeping and one for the alarm function. Confirm both turn smoothly, seat fully, and that neither shows damage from forced use or incorrect fitting. |
The Movement
The caliber 642 is a mechanical movement with an integrated alarm complication, meaning it carries two separate mainsprings: one to run the watch and one to power the alarm. It's a more involved movement than a standard time-only caliber, with additional levers and a hammer mechanism that requires careful attention during service. Jewel count data isn't available for this reference, but the movement is known to be sensitive to dried lubricants, which can affect both the timekeeping train and the alarm function independently.