Assembly Instructions Chapter 4

4-6 kW UHF Translator Chapter 4, Circuit Descriptions
837B, Rev. 0 4-22
The translator is now in the Operate
mode.
When Operate/Standby switch S1 is
moved to Standby, the other coil of
relay K1 energizes, causing the
contacts to open and a high (+12 VDC)
to be applied to U4B-9. The high at the
input causes the output at U4B-13 to
go high. The high biases on Q1 and
applies a low to the amber Standby
LED DS1, on the front panel, which
turns on and applies a low to Q2. This
causes Q2 to turn off and extinguishes
the green Operate LED DS2. When Q12
is biased on, the output from U2C goes
low and pulls the ALC voltages at J1
low; this lowers the gain of the external
amplifier trays. The high from U4B-13
is applied to Q4 and Q24, which are
biased on, and applies disables at J1-4
and J18-1. The high from U4B-13
connects to Q10, which is biased off.
The Q10 bias off removes the high from
Q6, Q7, Q8, and Q9, which are biased
off, and removes the -12 VDC enables
at J8-2, J8-3, J8-4, and J8-5, which
connect to the external amplifier trays.
The low applied to Q2 is also connected
to Q5 and Q26, which are biased off,
and the remote enable at J1-3 is
removed. The translator is now in the
Standby mode.
4.2.7.2 Automatic/Manual Switch S2
K2 is a magnetic latching relay that
switches the operation of the translator
to Automatic or Manual using
Auto/Manual switch S2 on the front
panel of the tray.
When S2 is set to the Auto position, the
operation of the translator is controlled
by the fault circuits and will stay in
Operate even if Operate/ Standby
switch S1 is moved to Standby. With
S2 in Auto, a low is applied to one coil
in the relay and this energizes and
closes the contacts. The closed contacts
apply a low to the green Automatic LED
DS3; as a result, DS3 is illuminated.
The low from the relay connects to
U5A, pin 2; U5D, pin 13; Q21; and
Q23. When Q21 and Q23 are biased
off, this causes their outputs to go
high. The high from Q21 connects to
the amber Manual LED DS4, on the
front panel, biasing it off, and to Q22,
biasing it on. The drain of Q22 goes low
and is applied to J8-7; this enables any
remote auto indicator connected to J8-
7. The low to Q23 biases it off and
removes the enable to any remote
manual indicator connected to J8-6.
When S2 is set to the Manual position,
the operation of the translator is no
longer controlled by the fault circuits, it
is controlled by Operate/Standby switch
S1. With S2 in Manual, a low is applied
to the other coil in the relay and this
energizes and opens the contacts. The
open contacts of the relay remove the
low from the green Automatic LED DS3
on the front panel and causes it to not
light. The high connects to U5A, pin 2;
U5D, pin 13; Q21; and Q23. Q21 and
Q23 are biased on; this causes their
outputs to go low. The low from Q21
connects to the amber Manual LED DS4
on the front panel, biasing it on, and to
Q22, biasing it off. The drain of Q22
goes high and is applied to J8-7; this
will disable any remote auto indicators
connected to J8-7. Q23 is biased on
and applies a low enable to any remote
manual indicator connected to J8-6.
4.2.7.3 Automatic Turning On and Off
of the Translator Using the Presence of
Video
The transmitter control board also
allows the translator to be turned on
and off by the presence of video at the
translator, when the translator is in
Auto. When a video fault occurs due to
the loss of video, J7-5 goes low. The
low is applied through W1, on J10, to
Q16, which is biased off, and to the red
Video Loss Fault LED DS9, on the front
panel, which will light. The drain of Q16
goes high and connects to U5B, pin 5,
causing the output at pin 4 to go low.
The low connects to Q18, which is