The Bendix ADF-T12-series direction finders are the Bendix
transistorized version of the old Motorola ADF-12. Any General Aviation
radio shop will have a book on this radio. The I.F. frequency is 140
kHz. The schematic set is a bit involved to scan, but the rear panel
Amphenol Blue-Ribbon connector pinout is as follows:
Pin 1 Sense antenna
Pin 2 Loop shield
Pin 3 Loop Input R1 (Tin)
Pin 4 Loop Input R2 (Copper)
Pin 5 Optional Audio Amp A+
Pin 6 Dial Lamps
Pin 7 Tuning Meter (ext)
Pin 8 47Hz switching Phase 2
Pin 9 Ground
Pin 10 Servo DC Output
Pin 11 Spare
Pin 12 47Hz switching Phase 1
Pin 13 Servo DC Output
Pin 14 Headset (500 ohm)
Pin 15 DC In +
Pin 16 ADF Servo Signal Output

The manual set I have is for the ADF-T12D with synthesized tuning. The
12B and C are infinitely more reliable than the D-model.. which is a dog!!!

Good luck with the project. de K3HVG



Henry Kolesnik wrote:
A freind has asked me to see if I can find any info on the subject aircraft
radio that covers 190 to 1750Kc in 3 bands. A schematic and IF frequency
would be nice. I can't find anything Googling.
tnx
73
Hank WD5JFR