Reference:pre-daytona-chronographs: Difference between revisions

[checked revision][checked revision]
Text audit: voice, clarity, source links
Text audit: voice, clarity, source links
Line 93: Line 93:
|}
|}


The Cal. 72B → Cal. 722 transition runs through the [[Reference:6238|6238]] itself. First-series 6238 production carried the unstamped Cal. 72B held over from the late 6234; the second-series redesign brought the Rolex-stamped Cal. 722 that then powered the 6239 and 6241. Russell Sheldrake documents the transition in ''Is the Rolex Pre-Daytona a Forgotten Classic?'' for A Collected Man (2020).
The Cal. 72B to Cal. 722 transition runs through the [[Reference:6238|6238]] itself. First-series 6238 production carried the unstamped Cal. 72B held over from the late 6234; the second-series redesign brought the Rolex-stamped Cal. 722 that then powered the 6239 and 6241. Russell Sheldrake documents the transition in ''Is the Rolex Pre-Daytona a Forgotten Classic?'' for A Collected Man (2020).


The frequency stays at 18,000 vph (2.5 Hz), 17 jewels, no hack and no quickset, all the way through to Cal. 727 in 1970, two references beyond the end of this line.
The frequency stays at 18,000 vph (2.5 Hz), 17 jewels, no hack and no quickset, all the way through to Cal. 727 in 1970, two references beyond the end of this line.