Chronograph A
1968–1971 · Stainless Steel · Manual Wind
About the Chronograph A
Made from 1968 through 1971, the Chronograph A uses Hamilton's caliber 643, a 17-jewel manual wind movement with 1/5-second stop watch timing, a tachometer scale, and a 30-minute recorder. The case is stainless steel with a round profile, and the two-toned dial pairs a white dial with two black subseconds registers, giving it the kind of purposeful, instrument-like look that defined chronographs of that era. The Chronograph A was part of Hamilton's broader push into sport and timing-oriented watches during the late 1960s, a segment the brand pursued seriously alongside its dress lines.
Finding a clean example means paying close attention to the dial, since the contrast between the white field and black subdials can hide fading or surface damage on casual inspection. The tachometer scale printed around the perimeter is particularly vulnerable to wear at the edges of the dial, and the raised gold hour markers can loosen or lose their finish over decades. A complete, unpolished case with legible chapter ring markings is worth holding out for.
From the Catalog
Hamilton positioned the Chronograph A within its Tachometer Chronograph line, describing the family as exceptionally accurate timepieces built around 1/5-second stop watch timing, a tachometer scale, and a 30-minute recorder. The stainless steel version retailed for $99.50 in 1968, a serious price point for the period that reflected the added complexity of the chronograph movement.
Hamilton Catalog Images
1968
What to Look For
| Dial | Look closely at both the white main dial and the two black subdials. The contrast between them can obscure condition problems at a glance. Check the tachometer scale around the perimeter for fading, cracking, or wear, and inspect the raised gold hour markers for loosening or discoloration. |
| Crystal | Check for deep scratches, crazing, or a replacement crystal that doesn't sit flush. A correct crystal matters on a chronograph, especially around the bezel edge where fitment affects the overall look. |
| Movement | The caliber 643 is a manual wind chronograph movement, and dried lubricants are a real concern on any movement of this age. On a chronograph specifically, dried oil creates enough friction to stop the movement or cause the chronograph function to seize. Budget for a full service, and keep in mind that parts for this caliber, including hands, can be genuinely difficult to source. |
| Case | Inspect the case for polishing. Swept lugs lose their definition quickly under a wheel, and a heavily polished case is hard to bring back. The caseback can be tricky to open without the right tools, so check for evidence of prying or damage around the edge. |
| Crown | The crown on a manual wind chronograph takes more regular use than a typical dress watch. Check that it threads or seats properly and that winding and hand-setting feel smooth, not gritty or loose. |
The Movement
The caliber 643 is a 17-jewel manual wind chronograph movement, meaning it needs to be wound regularly to run. It provides 1/5-second timing resolution, a 30-minute elapsed time recorder, and drives the tachometer function from the main dial. Chronograph movements of this type are more mechanically complex than a standard time-only movement, which makes service both more involved and more important to stay on top of.