The number of secondary turns in a microwave oven transformer (MOT) can vary depending on the specific design and manufacturer. However, Consequently, I cannot provide you with the exact number of secondary turns in a 1kW microwave.
Moreover, it's worth mentioning that the power rating of a microwave oven typically refers to its output power (the power of the microwaves generated for cooking), rather than the power rating of the transformer itself. The transformer's primary purpose is to step up the voltage from the power supply to a level suitable for the magnetron to generate microwaves, rather than being directly related to the output power of the microwave oven.
If you require specific details about a particular microwave oven model, I would recommend referring to the manufacturer's specifications or consulting the technical documentation for that specific device.