Measured characteristics : BW(-3dB) = 360 Hz, Ultimate Rejection < 90dB, 6/60 dB Shape factor # 3.2 a sine wave whose frequency is equal to the center frequency of the filter.
Using the same method, I then designed and build a 400 Hz Butterworth Filter and a 2700 Hz noise filter ( schematics below) with some of the remaining crystals : Crystal are available at frequencies about 15kHz and up providing the. Smaller box, has a much lower ultimate rejection. Large because first tests show that the same circuit, housed in a Picture shows the inside of the SSB ladder filter : its box is fairly Measured characteristics : BW(-3dB) = 2300 Hz, BandPass Ripple< 1ĭB, Insertion Loss 6 dB, Ultimate Rejection # 100dB, 6/ 80dB Shape factor # 1.6 I then selected a 2.3 kHz Chebycheff 0.1 dB design and, after many simulations with the W7ZOI programs, was ready to build the prototype : its schematic is presented below. Main characteristics are summarized below :įm = 7996.582 kHz Qm = 102000 Lm = 19.5 mH I selected 12 crystals to design an SSB filter : their ( # $1 each ) and sorted them out by frequencies and Q using a simple Impedances, the filters include matching transformers.įirst I bought a batch of 30 x 8 MHz crystals Modules of my home-made transceiver have 50 ohms input and output Other for CW (400 Hz) and the third as a noise filter. Makhinson N6NWP and others.īuilt 3 types of ladder crystal filters : one for SSB (2300 Hz), the Moreover, WHO estimates that 1.8 billion people use a fecally contaminated drinking water source, 2.5 billion lack access to improved sanitation facilities and more than 840,000 people die from water related diseases annually. Quickly that you have to pay a high price if you want good performanceĭevices : so I designed them by myself using methods proposed by According to the World Health Organization (WHO), 748 million people lack access to uncontaminated drinking water sources.
When it comes to crystal filters, it appears About half of our group is dedicated to working on problems related to a new kind of material, photonic crystals (also known as photonic band-gap materials).Photonic crystals are periodic dielectric structures that have a band gap that forbids propagation of a certain frequency range of light.