On 18 Aug 2009 at 23:56, Alan Melia wrote:

> However I suspect that the worst problem in Europe might well be 500kHz
> exactly, which is 16 times the TV line frequency. I dont think modern
> sets radiate so much at this frequency that they used to with CRTs, but
> I still have one or two CRT around me.

In fact it is 32 times the line frequency - 15.625kHz x 32 =500kHz
I do have a weakish carrier there, so that is probably what it is 
coming from.

What puzzles me about this thread is why you need such a narrow receive 
filter anyway. Blocking/intermod from broadcast stations is often 
stated as a problem on 500kHz but I get no problems here with my Datong 
UC1 (which has a tunable preselector but pretty broadband). If it is a 
problem then presumably a high pass filter passing above (say) 450kHz 
with a high attenuation below, or a notch at the frequency of a local 
LW station would surely be the better solution - or a better receive 
mixer.

73 Dave G3YMC

http://www.davesergeant.com