[Milsurplus] Fisher "Pilot" RDF, it's a boat DF.

[boeing377 at aol.com]

That radio in the photo is a marine RDF probably from the 1950s. I've used that very model back in the day. Was mfd by Fisher Labs in Palo Alto CA. Kaar, also in Palo Alto, made a few competing marine RDFs.

Having used many manual RDFs in pitching yawing rolling commercial fishing boats, I can tell you the ADF was a HUGE advantage, especially when trying to steer directly to a beacon in rough weather at night. 

I converted an ARN 7 for marine use and it worked great. I tweaked band 4 osc coil to get AM marine band comms in the 2-3 MHz band allowing me to shoot bearings on other boats too. 

Someone did a professional conversion of the SCR 269 (BC 433) system to cover the marine bad on band 3. The R 5 ARN 7 had four bands and went down to 100 kc. The BC 433 had 3 bands and went down to 200 kc. 

Jack Antonio kindly gave me a control box for the modified BC 433 and it looks like a stock military control head with a 2-3 MHz coverage on band 3. Someone made a new band switch label bezel and tuning dial with all the correct markings. I've always wondered who made these. I was told it was a ham in Southern CA but never was sure who or where. Quite a few were sold because they worked even better than the commercial gear of the day. The LP 21 loop had an ingenious mechanically programmable azimuth compensator that could remove the bearing distortion effects caused by metal rigging and structures.(masts booms etc). The commercial marine ADFs lacked this very helpful feature.

Those (Bendix?) ADF designs (ARN 7, MN 62, BC 433) were really well thought out: sensitive, fast bearings, thyratron loop servo motor controls, etc.

The commercially modified BC 433 ADF rcvrs  I saw had the osc coil can painted bright red. Would love to find one.

73
Mark 
AF6IM
www.parachutemobile.org