I did the last destructive test on the one coil remaining on the JW Miller 100Khz #1710 IF transformer. It's 62ft of wire ...and at 105 ohms per wire that works out to be bifilar #42 AWG. It also says the #1710 transformer is good for 18ma DC. Difficult to measure down that far with calipers and unknown insulation. 73s Kees K5BCQ