[Heathkit] HR-10B LATTICE FILTER?

[Ed - K9EW]

Hello to The List,

I see this question has been asked before, but I haven't come across
an answer...

I just acquired an HR-10B, and I'd like to narrow-up the crystal
half-lattice filter.  It looks like it's about 2000 Hz wide as built,
but I'd like to narrow it up to around 500 - 700 Hz for CW operation.
Installing a couple of new crystals seems like the way to go, but it
would be much easier if someone has already done this and could
provide the necessary information.

Has anyone out there already invented this wheel?

tnx es 73,
ed - k9ew
www.k9ew.us