We had a Motorola MSR-2000 lock on continuous due to a dropping-resistance 2N7000 FET PTT switch. It drifted low enough to keep the TX locked on but too high to allow the hardware TOT card to see the "keying" and drop the transmitter. The FET was on a homebrew FOB with 2N7000 PTT switch. Really glad we have a continuous-duty RFPA! 73, Duane KA1LM 42996