[Elecraft] [K2] AGC Time Constant

[Al Lorona]

I'm looking at the K2 schematic at the components on the Control Board that set the AGC time constant, and I can't understand how the fast setting gets its time constant... the parts involved, C4 and R2, appear to have a very long time, much longer than necessary for the FST settting. 

If you know what's going on could you contact me off-list to explain it to me? Thanks.
R,
Al  W6LX