From: John Welch (
Date: Wed Apr 14 1993 - 19:53:31 EDT

Vikki & I will be going to Dayton. Current schedule is for me to
talk about my DDS rig, the TW-1, probably on Saturday afternoon.
Will be explaining Direct Digital Synthesis (as best as I can :-)
and showing off the new board for it, that will allow you to run
it from 10Hz to 21.5MHz in 10Hz steps.

For those of you who didn't see it, the TW-1 was published in
Dec 92 and Jan 93 issues of 73 Magazine. As published, there was
an error in the DDS power supply schematic, an error in the
program and an error in the amplifier circuit board. Besides,
the amp isn't all it *should* have been anyway, and I'm working
on a better one.

It is currently a transmitter only, covering from roughly 3 Hz to
21.5MHz, stable as a rock, drift-free and repeatable. It is
expandable, and the first expansion is to change the diode matrix
board (that allowed you 12 'channels' wherever you wanted them)
with ROMS and thumbwheel switches to set it anyplace it can go.
Soon to be done are a receiver (still waffling about superhet or
phasing), a better amplifier, an up-mixer to allow full HF
coverage and a SSB generator.

Any questions, e-mail them to me at

72 es 73 all -->jjw

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