[Milsurplus] LO DFing, the myth that never dies!

[Ray Fantini]

With the development of the superhetrodyne receiver, modern style multi grid tubes, and the minimal amount of shielding between stages that almost every commercial or military receiver had by the mid thirties not to mention active RF stages that provide isolation from the mixer find it highly unlikely that much can be obtained or be of use from embassy listening at a distance of over several feet. Maybe in the teens and twenties when they still used regenerative receivers or some bread board triode stuff but not beyond that.
Ray Fantini KA3EKH