To: file hagen/wpfiles/430tx/buffer_deck_clamp_trig..wpd

From: Jon Hagen

Date: May 4, 2005

Subject: Operation of the new buffer deck clamp trigger circuit.

This circuit replaces the original pnpn diode clamp trigger in the buffer deck of the 430MHz transmitter.

Q1 and Q2 form a one-shot which produces a 100V, 10usec positive pulse at the grid of the clamp tube, V410. The trigger for this one-shot is represented by V1, and is a 200V positive pulse developed at the secondary of T411. Because the one-shot is made from a PNP and an NPN transistor, both transistors are off until a trigger is received. Then both transistors are turned on until the circuit times out.

The schematic fragment below show the circuit installed in the buffer deck.