N4YG
DDS Code Practice Oscillator: This kit is
a tone generator—not
a keyer.
The tone produced is a pleasing one, a sine wave or pure
tone,
not a square wave. Audio frequency is adjustable over a broad
range and the direct output to speaker is loud and clear.
On first assembling the kit, the
built-in
amplifier didn’t
work so I added a ‘temporary’
jack
to use an external amplifier. Later when the internal amplifier was
working I left the amplifier jack in place and added a speaker jack.
I also added a small relay to key the CPO from the one-watter’s
transmit signal. This might be better done electronically. The
power supply is a 9 volt battery and 7805
regulator.
At the Charleston Hamfest I picked up a
grab bag of PCB’s
and since then have
used one of them to consolidate the oscillator and mods onto one
board, making a somewhat neater package. At the same time I
replaced the relay with a DPDT version in order to use the second pole
for muting a receiver. The photo and video demo are of the original
messy assembly, however.
N4YG DDS Code Practice Oscillator Demo: CPO/CPO-Demo.mp4
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