4 Band Lowpass Filter Board

Board Design 

Ok, in the spirit of sharing and making things easy for people, I am going to start releasing some gerbers for the various boards I have designed for my various projects, that work HAHAHA, because, yes, not everything i do works.

I am not into this for making money, I do everything that i do simply for the love of it and for the learning experience. So selling boards and things is not high on my agenda. And besides, you can get 10 boards made and send to you from JLCpcb in China for not much more than it would cost me to send you one from Australia.

First cab off the ranks 7th order low pass filter boards. So you will notice there are no part values on the boards. Why? Well because i do not know what bands you might like to build for. The relays are double pole double throw in a standard 18x9mm package size. The transistors are anything you have in CBE footprint, I used 2n3904 and the resistor is there for current limiting, just pick a typical value, i think i used 4.8K.

SMA edge connectors bring RF in on the left side of the board. By default all relays are in the OFF position and no RF can pass through. The 6 pin header brings control signals and power to the board. To turn a relay on, a 5v control control signal is placed on one of the first 4 pins to turn 1 pair of relays on. The last 2 pins are ground and VCC of the relays you used.

For designing the filters I use an online calculator like this one at Calculators Edge: http://www.calculatoredge.com/electronics/bw%20pi%20low%20pass.htm Or a software tool like Elsie.

Lowpass Filter Board

Gerber Files can be downloaded from HERE:  http://vk4ffab.info/Files/LowPass_Filter.zip


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