Originally Posted by
rc-demon
Hello Howard,
I have completed my system, it is not picking up transponder. On my terminal screen there is nothing happening and led on decoder is not flashing when transponder passing under loop.
i have measured voltage at coax from decoder and it fluctuates alot anywhere from 4.66 - 4.79v , i dont think it should be changing that much?
If i measure voltage at at loop amplifier outputs it is a constant 0.57v
what validations can i do?
thanks for any help.
The first step is to make sure you have taken care of all of the errata items:
http://www.rctech.net/forum/12186635-post222.html
Next, make sure you are using the correct loop amplifier jumper settings to match up with the loop size.
Also, make sure you are using a compatible transponder!
Then we get down to the nitty-gritty: You can check the voltages on the loop amplifier against those on the schematic. Small deviations are inevitable, but large differences warrant further investigation.
Then trace the signal with an oscilloscope. The output should look similar to that in post #42:
http://www.rctech.net/forum/11764084-post42.html
If everything looks good here, then continue the signal tracing through the Phase Detectior Input Amplifier, which should finally come out as a nice squarish waveform at "PHASE_DETECTOR_IN".