Command Audio Mod for TiCK Keyer

© 2001 Larry Deering W2GL

Recently, I put a TiCK keyer into a Small Wonder Labs Green Mountain 40 Meter CW transceiver. The combination lead to dueling sidetones. The GM-40 has a built in sidetone, the TiCK sidetone is injected into the last audio stage, and the TiCK Kit comes with a piezoelectric audio transducer. Now I had three sidetones! My preference is to not have the audio disturb other occupants in the shack, so the Piezo was nipped to join history in the junk box. Of the two sidetones left, I didn't want to disturb the operation of the transciever. The GM-40 has a sidetone with an audio frequency of the difference between the transmitted and received frequencies. This feature is invaluable for zero beating other stations. Likewise, the TiCK sidetone can't be adjusted or deleted, as you need to hear the audio at setup. A switch could turn off the sidetone as required, but that complicates operation. My solution is a modification that splits the essential Command Audio out of the sidetone audio stream, and discards the Keyer Audio. This is a very easy circuit to build, and is described below. Of course, it would be nice if Embedded Research (who supply the TiCK) could program this change into their IC (maybe pin 2), making this modification obsolete. How about it guys?

Circuit Description

The circuit is mainly a quad NAND gate IC that uses +5V, GND, Audio, Keyline, and push button (*PBIN) connections from the TiCK IC. One gate is used to invert the Keyline signal to *keyline (not keyline or keyline bar). Two gates form an RS latch, the inputs to it are the *PBIN and *keyline. Command Mode is set by the pushbutton, forcing *PBIN low. The mode changes from Command Mode to Keyer Mode when *keyline goes low as the transmitter is keyed. The remaining gate blocks the audio in Keyer Mode, and passes audio in Command Mode. The resulting audio is cap coupled to a pot, and then to an appropriate spot with a resistor in the audio chain for the rig. The pot may be removed and replaced by fixed resistors once the values are known.


List of materials:

- 1 circuit board to mount components

C1 1 .1 uf capacitor, value selected for coupling to 10K load

C2 1 .01 uf capacitor, not critical, for decoupling

R1 1 10K single turn trim pot, adjusts sidetone volume

R2 1 100K 1/8 w, value is rig dependant

U1 1 74HCT132 quad two input NAND gate, RS #276-2827

P1 1 Piezo audio transducer, optional, comes with TiCK Kit. Connect to U1d-11 for Command Audio, or U1d-12 for original audio