Seen them on Ebay pretty cheap.  Going to connect up my Bendix aircraft ADF  with the loop and sense antennas. Maybe I will hear something usable.  

Jeep K3HVG 

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From: [email protected] <[email protected]> on behalf of B. Smith via MRCA <[email protected]>
Sent: Thursday, December 11, 2025 6:27:42 PM
To: Military Radio Collectors Association <[email protected]>
Subject: [MRCA] LF Loop

Several have asked for details on the rotatable loop on my Bendix 555 receiver.
Attached is a photo. You can estimate the turns etc. Note the use of a standard phone jack for the mount. The loop is shielded. I've posted in the past construction details for a loop for 80 meters. I've enjoyed the Bendix, it has a S meter, BFO, and a "Sense" antenna.
http://k4che.com/DFloopstick/DFstickpg1.htm
Z