[Milsurplus] LO radiation vs observation

[Hue Miller]

----- Original Message ----- 
From: "William Donzelli" <aw288 at osfn.org>

> > First, the detection range is of the order of a few to a few tens of miles.
> > i.e.: not really useful for searching wide areas.
> 
> Ten miles can make the difference if the sub has a clue where a convoy
> might be. A net of a few subs would have a real, albeit low, chance of
> intercepting a convoy. And two or three freighters sunk makes those
> expensive Scott radios look like a good deal, in hindsight. 
> 
> William Donzelli
> aw288 at osfn.org
> 

Ten miles could make a difference if you could establish that the 
Kriegsmarine boats ever used this technique. I believe 10 miles
was in visual contact range for days, and for nights, if there
was a convoy battle on, you would certainly hear the explosions
and see the flashes.
I recall reading about one of the classic convoy battles, and U-boats
were frequently ( at danger to themselves, altho probably not realized )
updating HQ about the proceedings, and HQ was sending frequent 
broadasts to update the whole U-boat pack on the proceedings. 
Another issue: in a convoy, the individual freighters would not 
necessarily even have a reason to have their MF receivers on, or
any receiver, actually; except maybe a morale radio. Because in convoy,
the ships communicated by blinker, TBS, or TBY  in the 72 MHz range.
Warships with better equipment, of course, were on constant 500 kHz
watch.  

I still think the "radio receiver leakage" issue was grasping at straws to
try to explain the grievous losses to US shipping in early 1942. Allied
with the "Loose Lips Sink Ships" posters and all that.  More likely than
your  SW-3 or Marconi regen (with RF stage) or some tipsy sailor in a
bar, were factors like fully lighted coastal cities silhouetting freighters
offshore, lack of adequate escort vessels, lack of air cover, ships sailing
individually without escort, and German radio stations in upstate NY
state and in Quebec province, Canada.  In the NY case, agents could
count the production of tanks by the numbers on railcars going to the port.
One thing that is still a mystery to me - the German station in Quebec,
near the St. Lawrence seaway- were they expected to reach Hamburg with
their 20 watt transmitter, or was there some unknown-to-us relay system?
( Project # 3006-B is to look up the "La Prense" ( sp? ) French Canadian 
newspaper article on this story. ) -Hue Miller