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
>
|
