DIY Doppler Radar – LNB Hack

I modified a satellite LNB to transmit as well as receive on 10ghz and connected the downconverted signal to my scope. I can use it to measure doppler shift and therefore speed of a moving object. I did the modifications by removing HEMT RF FETs and rotating them so their gate is where their drain was and vice versa. The source connections stayed grounded. I then had to cut some of the traces on the board and change a few resistors and things to make the biasing circuity work in reverse. I then capacitively coupled the dielectric resonant local oscillator the the transmitting section that I made. Watch Jeri Ellsworth’s Videos:

A similar mod can be done to use these as 10ghz ham radio transmitters:

Mod closeup pic:


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