====== Seiko 6600 ======
The **6600** series was a family of mechanical watch movements from [[Seiko]] in the 1960's.

Produced from [[1961]], the 6600 family was the basis of many later Seiko movements, including the [[Seiko 6100|6100 family]]. It ran at 18,000 A/h and used an [[automatic]] winding mechanism, Seiko's [[Magic Lever]]. The family was available in varying jewel counts 17, 19, or 21.

The first member of the lineup was the [[1961]] 6601A. Available with 17, 19, or 21 jewels and measuring 5.45 mm high, this basic movement nevertheless had a sophisticated automatic winding system. It was replaced by the 6601B later with unknown modifications. The 6606B and 6619A were launched in [[1965]] with a non-[[quickset]] day and date wheel and 21 jewels. It was not until the [[1968]] 6602B that Seiko reached a 45 hour power reserve, and this movement was 1 mm thinner.

  * Hand-wind - Officially 23.6 mm in diameter
    * 436/4361/66A (1960) - 23.6 or 24.1 mm, hand-wind
    * 66B (1960) - 23.6 or 24.1 mm, hand-wind
    * 957/6602B - 27.6 or 28.1 mm, hand-wind, dater Cal 66
    * 6618A (1966) - 24.1 mm, hand-wind
    * 6640A (1961) - 24.1 mm, hand-wind
    * 6642A - hand-wind
    * 6659A (1964) - 24.1 mm, hand-wind
    * 6660A - 24.1 mm, hand-wind
  * Automatic
    * 6601A (1961) - 27.6 or 28.1 mm, automatic
    * 6601B - 27.6 or 28.1 mm, automatic
    * 410?/6606B (1963) - 27.6 or 28.1 mm, automatic, day/date
    * 6619A (1964) - 27.6 or 28.1 mm, automatic
    * 245/2451
    * 790
  * 6605 (1962)
  * 660

^Winding ^Speed ^Model ^Year ^Jewels ^Power Reserve ^Notes ^
|Automatic |18000 |6601A, 6601B |1961 |17, 19, 21 |38 hours | |
|:::|:::|6602B |1968 |17 |45 hours |Date |
|:::|:::|6606B, 6619A |1965 |21 |38 hours |Day and date |

<WRAP ud ud_mov>

**Description:**
  * [[Automatic]] movement
  * [[Kif]]-[[Duofix]] escapement settings

**Functions:**
  * Hours, minutes, [[central seconds]]
  * Optional day and date

**Data:**
  * Diameter 12.25 ligne (27.6 mm), H 4.45 or 5.45 mm
  * 17 or 21 [[jewels]]
  * 18,000 A/h
  * Power reserve 38 to 45 Hours

**Production period:**
  * [[1961]]-
</WRAP>

{{tag>Movements Automatic_movements Seiko_calibres Suwa_Seikosha_calibres Magic_Lever_Movements}}