Hi Don, I'm not concerned in the slightest, it is to be expected and was just another measured data point in the discussion.
Regards, Mike VP8NO ----- Original Message ----- From: "Don Wilhelm" <w3...@embarqmail.com> To: "Mike Harris" <mike.har...@cwimail.fk> Cc: "Curt" <rhule...@comcast.net>; <elecraft@mailman.qth.net> Sent: Friday, November 05, 2010 3:12 PM Subject: Re: [Elecraft] [K2] Filters attenuation > 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 >> -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.864 / Virus Database: 271.1.1/3239 - Release Date: 11/05/10 04:34:00 ______________________________________________________________ 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
