Originally Posted by howardcano

Now that the transponder design is at a usable point, it’s time for an update on the decoder:

I designed an amplifier/line driver for the receiving loop, and it’s working quite nicely. I had originally considered just using a TV-style 300-to-75-ohm transformer to interface the loop to a length of RG6 cable, but the ones I found had a low frequency cutoff of 5 MHz, which is a bit too close to the transponder carrier frequency, and of course the voltage from the loop is reduced by the transformer, which didn’t appeal to me.