(Increasing relay speed)
This in many magazines published simple design for increasing the relay speed is often overlooked. The circuit speeds the relay by momentarily doubling the normal supply voltage and I added the gadget in a Ten Tec Corsair II and a linear (home brewed) amplifiers for speeding-up the T/R relays.
On receive the capacitor is charged to the supply voltage through both diodes. When the switch (PTT) is pushed, the transistor turns on through 1 kΩ by the charged capacitor. Then the relay momentarilyis supplied with twice its voltage and closes faster than normal without harming the coil. As soon as the capacitor discharges, the relay coil sees a normal supply voltage.