I am wanting to place a 45MHz, 2-pole crystal filter between the first
mixer output and 2nd IF input. (Mixer output is a SA602 and IF input is
SA605).

The mixer output is around 1500 Ohms and the IF input is around 4500
Ohms with 2.5pF capacitance parallel.

The required source and termination for the filter is 800 Ohms par with
3pF. The insertion loss of the filter is 2dB max.

Would the impedances be close enough to use resitive pad between mixer
and filter (680R in series with 1k2) and a small cap to ground across
the filter input.
Then a 980R resistor to ground at filter output and no capacitance (use
SA605 2.5pF and stray to make up the 3pF).

This would give total loss around 4.7dB.

Or would I be better to use say a tapped capacitor or L match from Mixer
to filter with
added C on filter input.

Apparently the SA605 has a "swet spot" for noise at around 800R so maybe
the Res to ground on the input would be ideal ???

Thanks for any help, I have not used crystal filters before and unsure
of implications of the approach.

Regards

David Huisman