[HBR] lattice filters for a modernized HBR approach

[Peter Bertini]

I got lucky and scored two pairs of half lattice crystals from two scrapped
Heath HR-10 receivers. Even better, I have the LO crystals to use them with
an 85 kc IF. Life is good again. So, for now my 1st IF will be at 1680 kc,
which is also free of local AM activity in this area.

Here's my quandary:  I can go with two half-lattice filters cascaded, or I
can use the two sets in a full lattice configuration. The full lattice looks

easier to implement, but I can't find much practical information on which
filter configuration would work the best. I may have a third pair coming,
which opens the possibility of adding a tail end half-lattice at the end of
the 1st IFA stage (there will be an active 1st IFA) to improve the filter
shape factor and stop band. Or, I could add the half-lattice after the
full-lattice, on the secondary of the final IFT.

Pete
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