Harris DX 25U, Техническое руководство

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lation monitor at LOW power is adjusted by the tap on L7. When
the transmitter is in the MEDIUM or HIGH power position, the
RF voltage from L7 will increase. Switched potentiometers R7
and R8 reduce the voltage to the desired level.
When relay K2 is energized, the mod monitor sample output is
taken from R7, MED PWR MON ADJ. When both K1 and K2
are energized the sample output is taken from R8, HIGH PWR
MON ADJ. Logic circuits on the LED Board provide logic HIGH
signals when the transmitter is in medium or high power. A logic
HIGH signal at J2-9 will turn on transistor Q4 and energize
low-voltage relay K2 for the MEDIUM power sample. A logic
HIGH signal at J2-7 will turn on Q3 and Q4 through CR18. This
will energize both K1 and K2 for the HIGH power sample.
H.2.2.12
+5 VDC And -5 VDC Regulators
DC supply inputs to the Output Monitor are +8 VDC and -8 VDC,
from the low voltage power supply. Each input is fused, with 0.5
A fuses F1 and F2, and regulated to +5 VDC and -5 VDC.
Series pass transistor Q1 is controlled by regulator U1-12. If
U1-9 detects an undervoltage or overvoltage condition, a +5
FAULT-L (LOW) signal is sent to the LED Board at J2-21.
The -5 Volt supply is similar, and uses regulator IC U4, and series
pass transistor Q2.
For a description of the regulator IC’s and circuit operation, refer
to SECTION M, DC Regulator.
DX-25U
H-4 888-2297-002 Rev. R: 11-11-96
WARNING: Disconnect primary power prior to servicing. 10/14/1999