Well, I fixed the problem.

My homemade coils/filters are OK. Using a signal generator, I applied
a 0.5 Vrms signal to the SB-610’s vertical amplifier input and got a
trace on the CRT that was about 1 inch high (thick), which meets the
specifications at 3.395 Mhz.

The problem was the 1 pf capacitor I used to couple the plate circuit
of the SB-301’s second IF amplifier to the SB-610. I raised this cap
to 6 pf and now have plenty of signal for the SB-610.

Thanks for all the advice. It saved time.

-Dave Drumheller, K3WQ