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Date: Thu, 30 Dec 2010 12:03:12 +0100
From: wolf_dl4yhf <dl4yhf@freenet.de>
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Subject: LF: LF "Mobile" ( was :  "NM" on 136177 )
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Hi Stefan,


you wrote:
 > This should allow me to easily receive 137 kHz while driving the car!
 > Hopefully there is not to much QRM during engine is running.
 > So maybe i can try a crossband QSO with DF6NM TXing on 137 and me 
answering on 30m while beeing on the highway :-)


Maybe, it's a Diesel engine, and the alternator properly low-pass 
filtered. I tried this years ago, and the QRM from the ignition coil, 
and / or the alternator was horrible. No big surprise that car radios 
with AM LF broadcast receivers have disappeared. And weak-signal 
reception "LF mobile" is even more a challenge.

In my Corolla, I would even have to disconnect the battery (!) if I was 
to receive VLF (and, most likely,  LF too) because some internal digital 
bus (most likely CAN or LIN) remains active, with the ignition and 
everything else turned off. For temporary V(!)LF operation on a remote 
site, I use a simple FM oscillator at the transmitter now, and listen to 
the VLF signals in the car's radio, using a distance of 10 m or so.


Cheers and a happy new year,
    Wolf DL4YHF .