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\page  pseudo_fsk_page Pseudo FSK

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Using the FLdigi Pseudo FSK (Rt. Channel) function to key a transmitter
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\image html config-rtty-tx.png "RTTY TX Configure"
\image latex config-rtty-tx.png "RTTY TX Configure" width=5.0in
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Select the PseudoFSK check boxes.
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FLdigi is now ready to generate a 1000 hertz tone burst signal on the
right channel of the stereo audio out of your sound card.
<br>

This tone burst is on when the RTTY bit is on and off when the RTTY bit is
off.  The left channel will be the normal AFSK signal.
<br>

The following circuit may be used to take the FLdigi PSEUDO-FSK signal from
the right channel of your SOUND CARD to key your transmitter's FSK
input line.  You may find it necessary to invert the sense of the keying
signal.
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\image html CWkeyingCircuit.png "CW Keying Circuit"
\image latex CWkeyingCircuit.png "CW Keying Circuit" width=6.0in
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<b>NOTE:</b>

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

<code>Catalog # 270-054, and Catalog # 273-1374</code>

Attach an audio cable from the Rt. Channel out of the your computer's
SOUND CARD to the input of this FSK  INTERFACE CIRCUIT (input of L1).
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Attach another cable from the output of this circuit to your
Rig's Keying FSK Jack.
<br>

Every PSEUDO-FSK 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.


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