the NPC / swing mod will work for the anytone quad 6, Stryker 955, Stryker 655, the anytone quad 5 and quad 5 end, it's all the same circuit. Cathode of 1N4148 signal diode to center pin of the a.m. regulator. I add a 47 ohm 2 watt resistor for slightly more peak, you can use up to a hundred ohm...