Doubling the internal clock speed of the 35SQ (from 8192Hz to 16384Hz) and with an increased accuracy of 0.1s/day (3s/month), the 36SQ claimed to better the 35SQ in all aspects. Whilst the story of the Suwa Seikosha produced Astron 35SQ is well known in watch circles, what isn’t so well known is that Daini Seikosha were developing their own quartz calibre at the same time, the 36SQ, which was released in 1970. Since 1959, Seiko had been split into two wholly owned subsiduaries, Suwa Seikosha and Daini Seikosha, in which no development information, movement design, or parts were shared, effectively making them rival companies within the Seiko brand. Despite costing ¥450,000, the same price as a small family car, they still found buyers (100 in the first month) and the model signalled the start of the quartz revolution. Several watch manufacturers had been developing quartz calibres throughout the 1960’s, but it was Seiko that were the first to market with the Astron 35SQ in December 1969. being one example, and a real eye-catcher. I’ve been looking at a few vintage quartz watches over the last few months, this Seiko 3923-5010 V.F.A.

Doxa Serial Numbers