- #Aade ssb crystal filter design how to
- #Aade ssb crystal filter design software
- #Aade ssb crystal filter design series
In the program I chose a crystal ladder filter, 5th order, Butterworth, bandwidth 3800Hz. The AADE Filter Design program expects ALL the crystals to have identical parameters. Let's design a 5 crystal ~14.318MHz bandpass filter using the values in the listing above having *** next to them. I usually buy about 25 crystals and can easily make 2 filters.Ĥ.) Simulate the resulting filter and adjust slightly if needed.ĥ.) Match the filter to the desired input and output impedances using transformers or L-networks.Ħ.) Construct the filter using good RF construction techniques.
#Aade ssb crystal filter design series
The crystals cut to be used in a parallel resonant circuit will have series resonances below 10.000MHz by a few to several kHz.Ģ.) Buy a group of crystals to measure so that you can pick ones with similar parameters. all have different series resonant frequencies. 10.000MHz crystals designed as series mode, 10pF parallel, 18pF parallel etc. Here are the basic steps:ġ.) Pick a frequency which is a common crystal frequency but near to the frequency you want. I have built about a dozen filters and can design, construct and test one in a few hours. Also consider some of the special crystal runs by the QRP clubs for crystals in the 7.040 to 7.060, 14.040 - 14.060, and other CW frequencies which are still reasonably priced. I have found that HC-49/U crystals usually have higher Qs than the smaller HC-49/US packages. Crystals (not crystal oscillators) are used with the resulting filter frequency usually a few kHz different than the number stamped on the crystal case. I generally match crystals first on Fs, Fp, and Q.Īssuming that you are not trying to design a crystal filter for an exact frequency, the procedure is actually quite easy to do. Notice that all the relevant crystal parameters are included. The table below shows the file created by the AIM 4170. Other VNA's could have the ability to automatically measure crystals but I do not know of any which have the necessary software. Using a small fixture with socket pins, crystals can be measured with precision at a rate of 2 to 3 per minute.
#Aade ssb crystal filter design software
The measurement of the crystal parameters has been automated in the software for the AIM 4170 VNA (also in the AIM 4170 UHF and VNA 2180). All the programs I have seen require the crystals to have identical parameters. There are several programs which can help design a crystal filter but I generally use the free AADE Filter Design program at which designs several types of crystal ladder filters. The difficulty always centered around measuring and selecting crystals and then designing the circuit.
#Aade ssb crystal filter design how to
There have been articles on how to design crystal filters in magazines for years.