Schematics

By Glen Millen VK2FC

 

QSK and Step-Start Schematics

The diagram below covers the overall 'QSK' schematic but I will also include a couple of variations to the relay timing section of the diagram.  These variations have been ones I have tested myself or been offered by other hams who have done similar modifications to the TL-922.

Schematic in PDF

  1. Diodes D5 through D9 form the tube bias supply. The number of diodes required for bias will depend on the type of tube used.  There is a small voltage drop across the solid state relay which adds to the bias. With the relay I used, 4 diodes are sufficient to obtain an idle current of approximately 200mA.

  2. The solid state D.C. relay is capable of switch approx. 2A and at one hundred volts.  8 to 12 volts and 14 mA of current flow to the input diode D4 is required to activate the relay.  This was purchased at Jaycar Electronics, catalogue number:- SY-4093

  3. The circuit comprising Q1, Q2, Q3 & Q4 provides a low voltage, low current interface to a modern transceiver to protect the transceiver's usually delicate amplifier keying circuitry.

  4. SW3 (standby) is the front panel switch on the TL-922.

Relay Timing

Horizontal time base set to 2mS per division. The upper trace is the antenna relay whilst the lower is the input relay.  This timing is achieved with the values shown in the schematic above.  On transmit, the antenna relay is activated 1.2 mS before the input relay and stays closed 1.4 mS longer than the input relay upon de-key. 

Step/Start Circuit

The circuit above shows the 240 VAC input wiring to the TL-922 plate and filament transformers.  The components in the blue shaded areas represent the additional parts required for the step/start power up circuit.  The relay (K1) is the former antenna relay from the TL-922.

Last updated on Monday, 04 October 2010

 

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