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

[Richard Brunner]

Re:
> .................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 never seen special gear for DF'ing receiver radiation, nor found
evidence that anyone did.  I have corresponded with Germans on this point,
and they never bothered, as they had better reliable resources.  Their
underwater listening gear could hear ship's screws at minimum 20 miles away.
When a sub found a convoy it would sometimes, upon request, broadcast a weak
beacon for other subs to home on.  I have found no reference to special
equipment, so the sub's beacon would be standard equipment at reduced
output, certainly measured in Watts, vs milliwatts or microwatts from a
receiver.

"The Metox Affair"  The Germans had a vhf receiver, the Metox, made in
France, to detect radar, and when they were routinely caught on the surface
with no radar warning, they suspected we were homing on Metox's receiver
radiation.  This was plausible because it used a 955 local oscillator and no
rf stage.  They then conducted tests by flying a plane with a vhf receiver
over at various altitudes, and found that receiver radiation could indeed be
detected at respectable distance depending on altitude.

500 m       12 sea miles/22 km
1,000 m    18 sea miles/33 km
2,000 m    25 sea miles/46 km

They then pulled the Metox receivers from service.  We were not listening,
rather had moved to microwave radar, which was undetectable on the Metox.

Reference: "Funkpeilung als alliierte Waffe gegen deutsche U-Boote
1939-1945," Arthur Bauer, 1997
Their "955" has, I think, a different number, but is the same construction.
I have the Metox schematic here somewhere.

Richard Brunner, AA1P