LEDs deflect fully to the right on peaks, with
the background noise at not more than half
scale. The FT-901 DM APF circuitry may help
in securing a proper signal-to-noise ratio under
difficult conditions.
(5) Once the proper input level has been set, flip
the RESET switch to clear the monitor screen
and initiate signal sampling. For the first eight
dots and dashes, the YR-901 will be sampling
the dot, dash, and space ratio of the incoming
signal. When this sampling period is finished,
the sampled letters will be displayed, and the
readout of the incoming signal will appear on
the monitor screen. If you want to start a
new page of copy, push CL; this will clear
the screen, but will not initiate a new sampl
ing cycle.
(
6) 1 f
the code speed changes by a factor of
greater than three (either 3 times as fast or
1 /3 as fast as the initial speed), the RESET
lever
must be flipped, in order to initiate a
new sampling. This is because a dash at the
initial speed will appear to be a dot at three
times that speed, and the YR-901 will be
unable to determine the proper ratio.
(7) Once the optimum copying tone has been
secured, you may switch the input bandpass
filter switch from WIDE to NAR, for even
more protection from adjacent channel inter
ference and noise. In the NAR position, the
input bandwidth becomes only 20
�H�z�,tp
so
tuning will become critical, but the signal-to
noise ratio will be greatly improved.
�(�8�)tp
To reverse the black/white relation on the
monitor screen, switch the NEG/POS switch
to NEG. In this mode, white letters will
appear on a black background.
(9) To hold copy in memory, press the M
(Memory) switch. All copy on the screen at
the moment that the switch is pressed will be
held. To recall the copy, press MR (Memory
Recall). The previously-stored copy will then
be displayed. Note that the YR-901 will
-(-,-+-TEU-,,E-I,
EYE+I,
I3I, -A-E-I-I-I
�-
-I
�- �-
�-�-�-�-�-�-�-�-�·__
-L
�-�-�·__
�'I,
�'I,
�'I,
�'I,
E'20�I-�---,I, -T-+I,
-+-+Eo-S-+-+-+I,
�'I,
�
E+E---�9�0--I,
�I__
�I__
EE---N
�9�0--I,
�A�FI, �I-+I,
F-0++
E'--S---S-,I,
-,E"'EUI,
FS0++
�00++
�00++
--E(l)ETI,
EA--I,
�00++ �00++
.PO
Fig.6
FT-901 DM + YR-901 + SP-901 +Video Monitor
CW
Monitor
-10-