8-Pole QER Crystal Filters

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Some would say a crystal-based IF filter is the very heart and soul of a good SSB rig. There’s no doubt that a clean, ripple-free and narrow-skirted “xtal” filter is essential for excellent performance, especially in a receiver. They are, however, among the most difficult builds for a home-brewing amateur to pull off. Among the easiest types, though, are quasi-equiripple designs that do require using xtals closely-matched in resonant frequency (within 50Hz, but the closer the better), but that do not require the careful measurement of “motional parameters” or ESR. More on QER crystal filters can be found in recent (since at least 2011) editions of the ARRL Handbook.

Kits and fully-assembled & tested filters are available for 4.9152, 9.00, 11.059, or 12.00MHz. Specify frequency when ordering. If you have requests or suggestions for frequencies, please use the “Contact” link button above to let us know.

User Guide

Schematic Diagram (PDF)

Github Repository

PC board only $4.95 Buy on eBay Buy on Tindie
Kit of PC board, matched crystals, associated capacitors, transformer toroids, and magnet wire $24.95 Buy on eBay Buy on Tindie
Fully designed, assembled, and tested (produced on demand, shipment within fourteen days of order). $49.95 Buy on eBay Buy on Tindie