Dear All,
Firstly I would like to thank Bruce et. al. for all their wonderful posts. I have noted some debate about the Seiko Twin Quartz models in the forum and if Seiko had "regular" production models that were spected to +-5 seconds per year. I have seen a number of different postings dealing with which production Seikos had this level of accuracy and thought it might be helpful to set the record straight.
First Seiko "high accuracy quartz" : 4883 +- 1 second a month. 1974
First Twin Quartz spected to +- 5 seconds per year: 9983 1978
Second Twin Quartz spected to +-5 Seconds per year: 9483 1981
Third Twin Quartz spected to +-5 Seconds per year:9681 1981
( the 9983 is model number, 1978 year of production )
All these were produced when Seiko had an internal competition between two different ways to regulate the Twin Quartz model. The JHQ method only was tuned down to +- 10 seconds and lost. All other twin quartz models, other than above, were spected at +- 10 seconds.
Last Astron Re-Issue.
And finally the version that is being discussed today.
When I have a bit of time I will post on the differences between the 9F and 8F series. Suffice it to say the 8F is considered within Seiko to be a much better movement than the 9F and much more stable and accurate. It was expensive to produce and parts of the design made it hard to fit into thinner cases. The 9F sealed 50 year "no maintence" module that is discussed here actually is used in a number of movements. The 9F movement is less resistant to temp and magnetic fields and costs about 30 percent less to produce the the 8F. The 9F is thinner, and used more common parts and the frame is used for a number of other movements and watches. The 8F is, without a doubt, the most robust high accuracy quartz movement ever made. But it is thick ( hence the better thermo performance).
The very high accuracy +- 5 second twin quartz movements above were extremely expensive to produce and were not robust in field use. Their biggest problem was they tended to get fried if worn in hot baths or shower rooms ( a real issue here in Japan where the harried salaryman has his watch with him in the afterwork Sauna to benchmark the last train).
Best, Thomas Polgar.
Firstly I would like to thank Bruce et. al. for all their wonderful posts. I have noted some debate about the Seiko Twin Quartz models in the forum and if Seiko had "regular" production models that were spected to +-5 seconds per year. I have seen a number of different postings dealing with which production Seikos had this level of accuracy and thought it might be helpful to set the record straight.
First Seiko "high accuracy quartz" : 4883 +- 1 second a month. 1974
First Twin Quartz spected to +- 5 seconds per year: 9983 1978
Second Twin Quartz spected to +-5 Seconds per year: 9483 1981
Third Twin Quartz spected to +-5 Seconds per year:9681 1981
( the 9983 is model number, 1978 year of production )
All these were produced when Seiko had an internal competition between two different ways to regulate the Twin Quartz model. The JHQ method only was tuned down to +- 10 seconds and lost. All other twin quartz models, other than above, were spected at +- 10 seconds.
Last Astron Re-Issue.
And finally the version that is being discussed today.
When I have a bit of time I will post on the differences between the 9F and 8F series. Suffice it to say the 8F is considered within Seiko to be a much better movement than the 9F and much more stable and accurate. It was expensive to produce and parts of the design made it hard to fit into thinner cases. The 9F sealed 50 year "no maintence" module that is discussed here actually is used in a number of movements. The 9F movement is less resistant to temp and magnetic fields and costs about 30 percent less to produce the the 8F. The 9F is thinner, and used more common parts and the frame is used for a number of other movements and watches. The 8F is, without a doubt, the most robust high accuracy quartz movement ever made. But it is thick ( hence the better thermo performance).
The very high accuracy +- 5 second twin quartz movements above were extremely expensive to produce and were not robust in field use. Their biggest problem was they tended to get fried if worn in hot baths or shower rooms ( a real issue here in Japan where the harried salaryman has his watch with him in the afterwork Sauna to benchmark the last train).
Best, Thomas Polgar.