Chris,

It looks like you have a broadcast station where it shouldn't be (at 
132.65kHz) and several other spurious stations in that area, so you 
may well have unwanted signals within the 136kHz band, especially at 
night (your recording seems to have been done during the middle of 
the day). You might improve things by by-passing the pre-amp. It 
would do no harm just by experimenting with an attenuator but why 
attenuate and amplify at the same time unless the preamp also 
provides another function such as matching? It seems the only 
front-end selectivity on that receiver is a narrow bandpass so you 
would really benefit from some additional wider filtering, eg an LPF 
with a cut-off just below the LW BC band.

Mike, G3XDV
==========

On 12 Feb 2018 at 14:11, Chris Wilson wrote:

> 
> 
> Hello  LF'ers,
> 
>   I would like to know if the experts here think I need an antenna
>   attenuator on 136kHz? I am using in this capture a little IDC
>   receiver:
> 
>   http://icas.to/lineup/idc-136-kit-eng.htm
> 
>   but see the same with a Softrock LF. I am unsure if the antenna is
>   overloading the RX, it's a big file at around 14 megs, but I guess
>   most people, unlike me in the sticks, have broadband :)
> 
> 
>   Thanks.
> 
>   http://www.gatesgarth.com/Untitled26.mp4
> 
> -- 
> Best regards,
>  Chris                          mailto:[email protected]
> 
>