b89. Datong and Timewave DSP-9
mods.
The Timewave DSP-9 (digital signal processor)
solves my desires for additional CW selectivity with my
Yaesu FT-902 and other equipment. Got it secondhand and resonable
priced years ago.
It was only one problem, the audio isn't bypassed when the unit
is switched off. So,
I added a relay for the audio from the transceiver, through DSP-9
to the loadspeaker.
Loosen the 4 screws at the sides and pull off the plastic covers
on front and rear.
Unscrew all the 4 screws for front and rear plates, then loosen
(not unscrew) the regulator
fixing screw near the rear plate (typical American design!), and
pull the board forwards
while making sure that the voltage regulator follows easy.
The printed circuit board with extra bypass relay. It is also
mounted an extra RCA phono
connector for audio output.
It is connected to a switch to select between Yaesu FT902 and
other equipment
A cable from the digital signal processor to the second
loadspeaker via this unit is suggested, but it hasn't really much
value
Some receivers have high impedance (600-4000 ohm) audio output
and a loadspeaker
transformer is used to match to the relative low impedance of
DSP-9 (with termination).
More info on page 22b
Datong RF speech processor...
Have only handdrawn circuit diagrams for it, and have not
found time to redraw them
Datong 60kHz RF speech processor board (bought at Ally-Pally
Rally in 1975)
Last updated 2004.12.29
Timewave DSP-9
Mods