Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_17 (call_sign VARCHAR, power__kw_ VARCHAR)

### Question ###
What's the call sign that has 20kw of power?

### Accurate SQL ###

SELECT call_sign FROM table_name_17 WHERE power__kw_ = "20kw"