[Milsurplus] Question ( RBS; submarine )

[Richard]

Another thing.  Back in those days all ships had DC power systems, so 
with a few motors running (commutator noise) I'm surprised they could 
hear anything.  QRP with a few Watts is eminently useful; I once used a 
Ten-Tec 509 with 2.5 to 3 Watts output with complete satisfaction.  I 
could work most everyone I could hear, BUT, that's many decibels 
stronger than milliwatts or microwatts.

Richard, AA1P


On 08/25/2016 05:21 PM, Ray Fantini wrote:
>
> I am still not buying it, the Afghanis in there mud huts believe that 
> the Americans can hear their conversations with drones five miles 
> above them. QRP operations in the Ham bands are a wonderful thing but 
> my experience of running low power CW and AM left me with the idea 
> that life is too short for QRP, lots of time spent calling other 
> stations or CQ with little response. If all the stars and planets are 
> in perfect alignment sometimes they get lucky and have a short 
> exchange and call that a QSO, but that’s just me.
>
> I would have thought German surface raiders in there short period of 
> time in operation relied on things like patrolling know shipping lanes 
> and approaches and visual sighting of smoke way before they would use 
> something as sketchy as receiver LO detection. And as to the noise 
> floor remember that we are talking about a ship that also had many 
> electrically powered motors and other potential noise sources.
>
> No, if no one here can’t sight a document I am sticking with LO 
> radiation being an issue in using multipole receivers in the same 
> location and the idea of long range LO direction finding a myth.
>
> Ray F/KA3EKH
>
> *From:*Nick England [mailto:navy.radio at gmail.com]
> *Sent:* Thursday, August 25, 2016 12:31 PM
> *To:* Ray Fantini <RAFANTINI at salisbury.edu>
> *Cc:* Military Surplus List <milsurplus at mailman.qth.net>
> *Subject:* Re: [Milsurplus] Question ( RBS; submarine )
>
> "It has been reported", .... but I don't know where -
>
> From http://www.tubedevices.net/Lorenz.php
> "It has been reported that a German raider during WWII indeed managed 
> to locate merchant ships sailing on their own, not in convoy, by 
> direction finding on the signal radiated by their receivers. 
> Presumably, these ships had rather old-fashioned equipment, perhaps 
> with an oscillating detector directly coupled to the antenna."
>
> Certainly NRL and USN training documents say that the purpose of 
> shielding and RF and stages was to prevent LO radiation that could be 
> tracked by enemy ships. The NRL history states this rationale for the 
> RAA, RAK, RAL, etc. designs, well before it could have been invented 
> as a "cover story" for Ultra, etc. So it seems there was certainly the 
> belief that it was possible.
>
> I'm not so hot to dismiss this as myth or misdirection - The middle of 
> the Atlantic in 1942 must have been pretty damn quiet RF-wise. 
> (Unimaginably quiet compared to my house.)  And an oscillator 
> connected to a nice long wire high above a steel ship in a salt water 
> ocean is not to be sneezed at.
>
> Current QRP efforts have shown 500+ mile reception on 80m with a 40 
> microwatt transmitter.
> Here's some 100mw 500kc results - http://www.w4dex.com/medfer.htm
>
>
> Nick England K4NYW
>
> www.navy-radio.com <http://www.navy-radio.com>
>
> On Thu, Aug 25, 2016 at 10:31 AM, Ray Fantini <RAFANTINI at salisbury.edu 
> <mailto:RAFANTINI at salisbury.edu>> wrote:
>
>     Can anyone anywhere document just one example of active LO
>     direction finding in use by any Navy in WW2? , I am not talking
>     about DF operations in fixing locations of submarines or surface
>     craft by receiving low to medium powered CW or AM transmissions,
>     or the practice of receiving radar emissions to identify
>     frequencies and pulse rates but the alleged practice of attempting
>     to receive the LO of a receiver at any distance beyond a hundred feet.
>
>
>
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