Steve, W2MY/5 wrote: The DSP is audio. Its got a sharper cutoff but can be affected by the AGC which is also audio. The crystals filters FL1 -FL4 are IF and closer to the front end and cut interference before the AGC.
--------------------------------------------- The K2 AGC is not audio AGC. It's derived from RF in a separate I.F. strip dedicated to producing an AGC voltage based on the strength of the signal at the I.F. and the AGC voltage controls the gain of the I.F. amplifier. The AGC circuits are on the control board. NE602 mixer U1 converts the I.F. signal to about 150 kHz. That way any BFO signal at 4.9 MHz can't get into the AGC system. The output of the NE602 is rectified to produce the DC AGC voltage that operates the "S" meter and which controls the gain of the MC1350 I.F. amplifier (U12) on the RF board. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
