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Re: LF: Strong signal on 137 kHz

To: "[email protected]" <[email protected]>
Subject: Re: LF: Strong signal on 137 kHz
From: DK7FC <[email protected]>
Date: Sun, 06 Apr 2014 21:31:31 +0200
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John,

Last night i've checked my 50 Hz sidebands (actually 100 Hz) on LF by using SpecLab and a Tecsun PL660 receiver, both running on batteries (ferrite antenna) and coupled via a cable.
The sidebands are at -40 dBc, see attachment.

So maybe the problem is on your side. I remember a similar effect by MF WSPR decodes by a EA station. From that station i'm often getting 2 decodes in the same time slot, beeing 100 Hz distant and just 10 dB or so in SNR difference, which is also not caused on my side... Maybe a galvanic coupling with some mains harmonic currents on the antenna cable?
73, Stefan/DK7FC


Am 30.03.2014 23:25, schrieb DK7FC:
[...]
I can't explain the -20 dBc sidebands. I've measured my sidebands to be -35 dBc 
some time ago and didn't change anything on the LF setup. I'll check it soon 
again.

73, Stefan/DK7FC

Am 30.03.2014 13:00, schrieb John Rabson:
This morning at about 0745Z I received a signal which seemed to be QRSS. It would have 
been a strong signal except that I’m still suffering from severe QRM.  I was 
unable to identify it, but there were traces of 50 Hz side bands about -20 dBc.

This was the first signal I had received for some weeks. I’m still hunting the 
source of interference.

73
John F5VLF

Attachment: -40dBc.png
Description: PNG image

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