Mike, Your results are not all that abnormal. Most do not begin to encounter attenuation until less than 400 Hz, so yours is slightly worse off than normal in that regard - but then I usually consider 2 dB to be within measurement error range. However, I was concerned about those who said they had significant attenuation at 700 Hz.
Even though there is attenuation at the narrow filter settings, the filters are still quite usable for combating QRM. On the lower bands, the band-noise is typically high enough that adding more gain is not beneficial unless your antenna is inefficient, but on the higher bands, running with the preamp on will more than make up for the few dB loss of the narrow filter. In other words, while this is an interesting topic for those of us with measuring tools (signal generator and Spectrogram), it is not likely to make a huge difference in actual operating. 73, Don W3FPR On 11/5/2010 1:29 PM, Mike Harris wrote: > > Measured using Spectrogram ref level for audio peak -90dB. The > sound card in my PC isn't particularly good and this low level > eliminates displayed audio harmonics. > > Filter: > 1000Hz -90 (ref) > 700Hz -90 > 400Hz -92 > 200Hz - 94 > > FWIW. > > Regards, > > Mike VP8NO > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
