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_39417 ( "Call sign" text, "Frequency MHz" real, "City of license" text, "ERP W" real, "Class" text, "FCC info" text )

### Question ###
What is K236AM's lowest frequency in MHz?

### Accurate SQL ###

SELECT MIN("Frequency MHz") FROM table_39417 WHERE "Call sign" = 'k236am'