Fldigi Users Manual  4.1.17
CW Keying
Timing and QSK

Click on the Configure menu item to open the fldigi configuration dialog. Click on the Modems tab and then on the QSK tab.

  1. Set the Pre Timing and Post Timing to zero.
  2. Activate the QSK feature by clicking "QSK on right channel".

Click the CW tab and adjust the CW settings to your preference. Use the Test char and the Send continuous controls to ease the adjustment process.

FLdigi is now ready to generate a 1600 hertz CW tone on the right channel of the stereo audio out of your sound card.

The left channel will be the normal raised cosine shaped CW wave form that you may use for your side tone.

The following circuit may be used to take the FLdigi QSK OUT signal from the right channel of your SOUND CARD to key your transmitter or a QSK circuit.

CW Keying Circuit

NOTE: L1 - Radio Shack has two items that may be used for this isolation transformer.

  • Catalog # 270-054
  • Catalog # 273-1374

Attach an audio cable from the Rt. Channel out of the your computer's SOUND CARD to the input of this QSK INTERFACE CIRCUIT (input of L1).

Attach another cable from the output of this circuit to your Rig's Keying Jack.mall>

Every CW tone that is generated by FLdigi is rectified by this FULL WAVE VOLTAGE DOUBLER circuit. The resultant voltage turns the Q1 transistor on and "grounds" the collector, which takes the RIG'S CW KEYING JACK to ground and "keys" the transmitter.

You can adjust the start and stop timing of the QSK circuit relative to the CW waveform with the "pre" and "post" settings.

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