RELAY STEP-UP OR SPEED-UP FOR DECREASING PULL-IN TIME
This in many magazines published simple design for increasing the relay pull-in time is often overlooked. This circuit works by using a short burst of the double supply voltage to move the contacts and then applies the original volts to the relay to lock the contacts in place.
I added the gadget in a Ten Tec Corsair II and all my linear 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 momentarily is 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.