Helical Resonator Dimensions Crystal Filters Types 10 MHz SSB Ladder X-tal Filter 3.58 MHz CW Ladder Filter - N2DCH Variable Bandwidth X-tal Filter - G3UUR Variable Quartz Filter 4.43 MHz SSB Filter 27 MHz - 40 MHz Lumped Component Diplexer 430 MHz to 780 MHz Tunable Filter 88 MHz - 108 MHz Notch Filter Notch-Filter using Coax Cable Variable Bandwidth X-tal Filter - LA7MI HF Butterworth BPF - IK4AUY HF Front-End LPF/HPF - IK4AUY 9 MHz Ladder Crystal Filter One Crystal CW/SSB Filter - DL7HG Variable 600 Hz - 1 kHz Crystal Filter - DL2TM 4 MHz Active Crystal Filter - DJ1RL Diplexer IF-amplifier - OE3HKL Various Ladder Crystal Filters - S54S 1.3 GHz / 2.4 GHz / 3.4 GHz BPF - DL3NQ 1296 MHz BPF - DC0DA 144 MHz High-Q High-Power BPF 1296 MHz Interdigital BPF Loop Filter Options for PLLs - DB1NV 9 MHz IF Notch Filter 455 kHz IF with Mechanical Filter Symmetrical Bandwidth Ladder Crystal Filters - DK4SX Ladder Filter with Overtone Crystals - DJ6EV 4.43MHz Neutralized Ladder X-tal Filter -K6OLG Stubs as Resonators 1296 MHz Cavity Band Pass Filter - N6CA 1540 MHz Interdigital Filter Roofing Crystal Filter 2nd Order RC All-Pass Filters Phase  Relations in Polyphase Networks 9 MHz CW Roofing Filter - PA3AKE 9 MHz SSB Roofing Filter - PA3AKE 10 GHz Band Pass Filter - W1VT Helical Filter Calculation Narrow-Band LC Matching Networks Calculation 1300 MHz Cavity Band Pass Filter - N6CA 2304 MHz Cavity Band Pass Filter - N6CA Three-Post Two-Sections Cavity Filters - W1GHz 3.58 MHz Buterworth SSB X-tal Filter - W7ZOI 1013 MHz, 2MHz-BW Cavity Filter Dual Ladder Filter for SSB - N2DCH No-Tuned Circuits X-tal Filter 4.43 MHz 9-poles SSB Filter HF BPF and LPF Filters 1 GHz Zero-Order-Resonators Band Pass Filter 144 MHz - 432 MHz Diplexer Iulian Rosu http://www.qsl.net/va3iul/