EMRFD Message Archive 8087
Message Date From Subject 8087 2013-01-09 17:30:14 thomas Diplexer filters for amplifiers Hello.
I just uploaded 2 files to the files section. One is an program to calculate the diplexer filters described by Sabin in QEX 07/1999 and on the EMRFD CD.
The other file shows an QUCS simulation of an filter designed for 14MHz.
The program is an product of me having to learn C#, so the code is not as good as it should be, but it works.
There are no error detection buildt in, so any unrealistic values to the input boxes may result in the program terminating. If the values gotten are unrealistic high, replace the comma with an punctum in the K value, as this is depending on the regional settings on your computer.
All users should read and understand Sabins article, as it explains the design process.
The Frequency box is for the low pass filter -3dB frequency, so use an suitable frequency above the band you are designing for. Running some simulations to see the frequency responce and filter loss is valuble, and there may be need for some recalculations to find the compromy between filter loss and stopband attenuation.
In my experience those filters improve the IMD of an amplifier, compared to classical low pass filters.
Feel free to try, and please give feedback. If I can find an way to export an file with the values to GPLA I'l incorporate that, but for now you have to enter the values manualy.
73 de Thomas LA3PNA.