K1EL
Morse Code Practice Oscillator
CPO
CPO Datasheet – A.3
4/10/2020
Page
14
Note that the FSK input is only used when the CPO is in RTTY test tone mode which
happens when the pitch control is adjusted fully clockwise. That is the only time the CPO
will look at the FSK input. So in normal operating mode you can use a mono plug for the
key input and it will key the CPO just fine.
Pushbutton hint: The pushbuttons can be activated two ways, either by pressing in on
the button (which is rather difficult) or by pushing the button so that it tilts down.
The CPO will output a tone in three different ways:
Internal Speaker:
is intended for practicing at a low volume level so as not to disturb
others. The speaker’s output varies with frequency so you will find some frequencies are
much louder than others. The volume control will affect the internal speaker volume.
External Speaker/Headphones:
A more flexible option is to use the external speaker
connector. This can drive a set of stereo headphones or an external 4-16 ohm speaker.
Note that the external speaker must be wired with a stereo connector as shown below:
GND
N/C
SPEAKER LEAD
Figure 17 – CPO External Speaker Connections
Audio Line Out:
The audio line out connector provides a high impedance (10K) output
level that is adjustable by trimmer between 0 and .4 V RMS. This is a very useful for
generating tones for remote CW operation or to feed a powerful audio amplifier to fill a
room with Morse tones. A mono or stereo plug can be used for the line output connector.