Arduino based CTCSS encoder
Several years ago I've owned a Kenwood TR751E and I've always regretted that I've sold this rig as looking back it was the best 2m multimode transceiver I've ever owned. So when I suddenly got the chance to buy, in very good condition, not only the TR751E but also the TR851E as a pair of transceivers I didn't think twice !
However one disadvantage of older generation transceivers is that they don't have any CTCSS system. Especially the encoder part is a lack as most repeaters use these tones nowadays.