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#1
May 8th 08, 12:56 AM
posted to rec.radio.shortwave
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CW narrow filters
On May 7, 3:12*pm, joe wrote:
RHF wrote: On May 6, 10:38 pm, Telamon M... Sushi, Should not the Two separate IF Filters of the same Band-Width : one for the 1st IF and one for the 2nd IF create a Series RF Signal Path resulting in a better combined Filtering Shape Factor then one along; plus improve the Ultimate Rejection of the RF Signal Path. Shape Factor : 2.0 & 2.0 = 1.4 Ultimate Rejection : 60 dB & 60 dB = 90 dB SNIP - That's some very interesting math you got going there. - - -- - Telamon - Ventura, California Telamon - Did I say it was "Math" ? Shape Factor : 2.0 (1st IF) and 2.0 (2nd IF) comes out to roughly 1.4 at the end of the IF Processing Stages in the Signal Path. OK so 60 dB was a bad number so make it 85 dB. Ultimate Rejection : 85 dB (1st IF) and 85 dB (2nd IF) comes out to roughly 127 dB at the end of the IF Processing Stages in the Signal Path. practically speaking - no math required ~ RHF *. RHF, As far as I know there is no general method that allows you to combine shape factors for two filters into a number describing the net result. I also know of no general method for combining rejection of two filters to give a meaningful net number. So, please tell us how you arrive at these numbers.- Hide quoted text - - Show quoted text - FM ! ~ RHF |
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