[Elecraft] cascaded filters for the K2

[Masleid, Michael A.]

Hello Merlin,

>Anybody out there remember Doug deMauw's brilliant receiver designs, =
with a=20
>crystal filter in front of the IF amplifier and another one at the =
output of=20
>the IF amplifier?

The K2 does have crystal filters on both sides of the IF amplifier.
(X5 and X6 are part of the post IF filter).  I'd guess that a
daughter board off of that area would couple back into the SSB
adapter's filter in a nasty way unless you add a lot of shielding.

>tapping into the spot between the existing filter's output toroid=20
>and the plug that goes into the RF board.

Remember, the SSB filter is also used on transmit.  U5 will be pumping
the TX signal through this area part of the time. =20

I'd think for quick test purposes, the noise blanker is the place
to experiment.  The tap in points are available there.

>with another seven poles it would be as good as there is.

I'd think that you'd have to be careful to match the bumps and dips
in one filter to the dips and bumps in the other.

73, de Michael, AB9GV