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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: Spring Global <[email protected]>
Date: Fri, 11 Apr 2014 09:20:17 +0200
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Could be a neighbour with plasma tv. I have the same with the plasma at home on 
many bands in hF

Sent from my iPad

> On 6 apr. 2014, at 21:57, John Rabson <[email protected]> wrote:
> Stefan,
> On previous occasions when I have noticed side bands on your transmission, 
> they have been at worst -40 dBc which is why I was puzzled about the -20. It 
> did not make sense. You will note I did not originally suggest whose side 
> bands they were as I was not able to identify the transmission.
> I have been doing some further checking here and the matter seems to be 
> complicated by a lot of strong signals with 50 and 100 spacing across the 
> band. Thank you for the suggestion about galvanic coupling. If the weather is 
> fine tomorrow I will check the joints in the loop antenna I use for reception.
> 73,
> John  F5VLF
>> On 6 Apr 2014, at 21:31CEST, DK7FC <[email protected]> wrote:
>> 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

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