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After C6 is charged through the parallel R22 and R23, Q7 is again
turned on and the pause signal begins. This pause signal is longer
because of the 1 meg charging path for C7. When C7 becomes charged,
Q8 is turned on and the negative signal from the collector of Q8
starts the cycle again at the next Letter PWB. The trigger out
connection on the last Letter PWB is open.
Letter PWB's will usually be programmed before shipment from the
factory. However, if the Identifier is not known before shipment,
unprogrammed PWB's will be supplied. An unprogrammed keyer may be
placed in service by performing the following operations on each
letter PWB.
(a)
Place a jumper in one of the jumper positions J4 through Jl.
This jumper marks the start of the letter and would be placed
in J4 for a four bit letter, J3 for a three bit letter, etc.
(b)
Observing the Letter PWB schematic and assembly drawing, the
letter bits will now be generated in sequence from left to
right on the schematic starting with the jumpered stage. Dashes
will be generated automatically and any dash may be changed
to a dot by adding a 220K ohm resistor in parallel as shown
in dotted lines. Also, if Jl is installed remove R21; J2 is
installed remove RI4; J3 is installed remove R7.
2.2.4.2 Number PWB
Number PWB's are electrically identical to Letter PWB's except for
the addition of a fifth multivibrator circuit to generate the fifth
bit of a number.
Programming a Number PWB follows the same procedures as programming
a Letter PWB. Place a jumper at J5, and place 220K ohm resistors
in position where a dot is to be generated. Note that the first
bit is position J5, the second bit position J4, etc. Also, if Jl
is installed remove R28; J2 is installed remove R21; J3 is installed
remove RI4; J4 is installed remove R7.
2.2.4.3 AM Recycle PWB
The AM Recycle PWB operates in a normal code identification mode
whenever switch S1 on the AM Recycle PWB is in the IDENT position.
When $I is in the CONT position, a continuous tone is generated,
and when the switch $I is in the CARR position, a steady carrier
with no modulation is produced.
26
Southern Avionics
SS-800AVS
Company
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