Re: The APF feature of the K3.
Posted by
Bill W4ZV on
Feb 04, 2011; 1:46pm
URL: http://elecraft.85.s1.nabble.com/The-APF-feature-of-the-K3-tp5990251p5992625.html
APF was discussed extensively in August 2009 (check the archives) including a simulation of the exact FT-1000D APF analog circuit which I found and sent to Al W6LX. Here's Al's simulation which was the model for the K3's DSP implementation of APF:
http://sites.google.com/site/ft1000apf/w6lxanalysisoftheapfcircuitintheft-1000If you search online, you can find the FT-1000D Service Manual which has the analog APF circuit (less the front panel control pot VR8901-2 which is 1k ohms). You must use the original resistor values, not those later changed in a Yaesu service bulletin (to address complaints of peakiness...which in fact is what makes it work). Connoisseurs of APF that bought later "improved" FT-1000Ds quickly discovered its APF was not as effective as the original and reverted to the original "peaky" design:
http://lists.contesting.com/_topband/2000-03/msg00027.html73, Bill