 A production contract for 3 @,@ 000 units was immediately started at EMI , Pye , and EKCO . When they left for the USA in August , the Tizard Mission team took a Mk . IV , ASV Mk . II and IFF Mk . II with them , via the National Research Council ( Canada ) . During the following discussions , it was agreed that the US would produce AI , while Canada would produce ASV . Western Electric arranged a production license for the Mk . IV in the US , where it was known as the SCR @-@ 540 . Deliveries began for the P @-@ 70 ( A @-@ 20 Havoc ) and PV @-@ 1 aircraft in 1942 . 
