Hello Stewart, Tail end IF Filter: Given that the prime purpose of the 2nd IF Crystal filter is to reduce wideband noise created by the MC1350 IF amplifier, which comes out as audio "hiss", yes a better filter would do a better job provided that it is wider than the SSB filter. BUT I suspect that the MC1350 would not be happy driving such a filter with its varying input impedance. More distortion / intermod would result than when driving the two crystal filter. The other possibility is that the drive to the AGC system could "bounce" due to these impedance variations, and depending on time constants etc oscillation at some frequency high or low could result. An Image Reject Demodulator can eliminate the need for any "tail end" filter, but no room,
AGC Take-off point. Here I am guessing. It could be 1) To reduce the BFO signal leaking through the demodulator that might drive the AGC. The filter chops this down. 2) A simple matter of drive level 3) To reduce AGC Attack delay. 73. Geoff, GM4ESD ----- Original Message ----- From: "Stewart Baker" <[EMAIL PROTECTED]> To: "Elecraft Reflector" <[email protected]> Sent: Saturday, March 05, 2005 11:27 AM Subject: [Elecraft] K2 - 2nd Xtal Filter Anyone any experience of, or thoughts about adding another 3 crystals to the K2 2nd crystal filter ? 73 Stewart G3RXQ _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
