Indoor Broadband Transmitter – ITX21-100
IM4030013-1 Rev –
8
2.3 Power Supply Assembly
Two +12 VDC and one +24 VDC power supplies are used to provide the DC voltage. A
+12 VDC linear power supply is used to provide power to the internal downconverter and
Local Oscillator. A 5 VDC regulator is only used for the TTL switch for the power amplifier.
The MDS downconverter is powered by a 24 VDC power supply. A +12 VDC switching
power supply is used to power everything else in the compact transmitter.
2.4 Diagnostic Circuits1
The
ITX21-100transmitter has several connectors and switches.
Connectors -
There are two monitor connectors on the front panel. The transmitter’s input
and output at VHF can be viewed at the “VHF MONITOR” port on the front panel.
Selection is by a toggle switch, which energizes a 12 VDC coaxial relay. The “INPUT”
position selects a sample of the VHF input directly. The “OUTPUT” position selects the
VHF spectrum downconverted from a sample of the microwave output of the power
amplifier. The downconversion is performed by an internal MDS downconverter with the
same LO as the compact transmitter. The transmitters output at microwave can be viewed
at the “RF MONITOR” port on the front panel. The signal is a sample of the power
amplifiers output thru a 40 dB coupler.
DC Voltage Diagnostics –
DC voltage diagnostic signals can be read using the built- in
meter on the front panel. The functions available are shown below:
12V
RF
NOT USED
NOT USED
READING FROM 11.5V to 12.5V
READING FROM 0.2V to 1.0V
1.
+12 VDC of power supply, volts
2. RF
detector
of power amp, volts
Figure 4. DC Diagnostics Switch Positions.
Power "On/Off" Switch Panel
– The power amp switch a5VDC to the power
amplifier’s TTL circuit, which shuts down the power amplifier.
2.5 On-Delay Timer Assembly
A relay and binary counter is used to delay power to the amplifier. This is so the +12 VDC
power supply has a chance to stabilize upon start up of the Transmitter. The counter is set
for an 8 second delay upon start up of the transmitter.
1See Data Manual for nominal values of diagnostic signals.
Содержание ITX21-100
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