[Milsurplus] Re: DFing receiver re-radiation in WW 2?

[BOEING377 at aol.com]

There was apparently a lot of concern in WW 2 about receivers radiating 
signals that would give away their presence and possibly allow direction finding by 
enemies.  Some had special circuits to suppress such radiation before it 
could reach the antenna (e.g., ARR 7).  Did the US or its enemies have special 
gear for DFing receiver reradiation? I really doubt that standard DF gear would 
do the job.  I have had lots of experience with ARN 7 Radio Compass eqpt as 
well as later commercial marine DF gear and it took a reasonably strong signal to 
give a trackable null.  I don't doubt that you could detect a relatively low 
powered radiated IF signal at some distance, but DFing it with a small loop 
seems doubtful to me unless you were very very close.