[Milsurplus] L.O. radiation

[Radioman390 at cs.com]

"Ralph Cameron" <ramcam at magma.ca> wrote:

>There have been several documented cases of radio agencies locating clandestine operations from receiver L.O. emissions. In some cases they were able to determine the actual frequency being received.
>
>The Canadian military has a requirement for a specified minimum radiated signal ( in dBw) for spectrum analyzers and the same holds true for intercept receivers. Maybe they believe in myths.
>
>73
>Ralph VE3BBM
>

Actually, regerenative receivers, especially for VLF (below 300 kHz) were made into the 1970s. I have a transistorized Radiomarine VLF receiver (I got it new!) made while Radiomarine was part of EAC (Electronic Assistance Corp.) at the same time they were making R-390As for the military. I believe Fred Osterman included a picture of it in his book "Radio Receivers Past & Present", although he misidentified it as an RCA Radiomarine. It was an EAC-Radiomarine. EAC also owned Hammarlund for a while. My friend, Bob Edwards, was chairman of the Board. An improperly squelched regen radiates like hell.

Another indication that LO signals get out a ways is that a TV ratings outfit in the 60s was able to determine what TV channel you were watching by driving a van down the street with a big loop on the front, which would pickup the TV set's LO signal, and identify the channel. Similarly another ratings outfit had receivers by the side of the road to pickup LOs from passing cars and calculate the channel tuned to.______________________________________________________________
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