Re: LF: Strong signal on 137 kHz

[DK7FC <73dk7fc@googlemail.com>]

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
> >

-40dBc.png
Description: PNG image