Quote:
Originally Posted by ORAWA01
Just wondering if LOW PASS filters for blocking MW signals appearing on SW or LW bands are worthwhile investment.
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I may have misunderstood the above, but if a low-pass filter is installed to block MW signals then all signals
above MW frequencies will be blocked also, i.e. all signals on the SW bands. However, since LW signal are
lower in frequency that MW signals, they will will not be so blocked.
However, judging from what you have written, it does sound to me that the fitting of such a filter, be that low-pass, high-pass or even band-pass is simply tackling your problem the wrong way. It does sound as though you have an overload of signal strengths reaching your receiver producing severe cross-modulation. There is a strong possibility that there is a fault in your receiver that is allowing strong off-tune signals to cause such cross modulation: I would investigate that path first.
Failing that, the fitment of an AMU / ATU
* between aerial and receiver would be worth a try or even a variable resistive attenuator should help.
There is also the possibility that in your locality there may be a transmitter producing high field strengths driving the 'front end' of your receiver into non-linearity, in which case, the fitment of that ATU / AMU, perhaps plus an attenuator, should help.
A further thought: You also wrote "using larger antennas and amplified antennas at nights". That is really not helping matters! Your aerial is probably picking up quite adequate signal strengths: the amplifier is probably getting driven into non-linearity. Remove that amplifier and see if doing that helps.
*Aerial matching unit / Aerial tuning unit
Al.