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User Manual
Rev. 1.2 - 24/01/11
PTX-DDS
9.2 Power supply unit
The
PTX-DDS
power supply unit is a switching-type unit whose +34 V main output
powers the machine’s RF amplifier. The power supply also features stabilizers for
generating cont5 V, -15V, +8V and +18 V voltages for powering the other
device circuits.
9.3 Power amplifier
The power amplifier is available in a 30W,100W and 150W version.
The final power stage is enclosed in a fully shielded metal container fixed to the
central part of the device.
The RF signal coming from the main board reached the pilot, is amplified and
then sent to the final stage which takes care of final amplification up to 30, 100 or
150W (depending the model).
Amplification occurs in two stages, the first done with the BLF244, and the second
with a BLF147.
Besides actual RF amplification, this circuit performs other functions:
• Checks output power level depending on the setting
• Reduces delivered power in presence of high-level reflected power
• Measures direct and reflected power by means of directional couplers
• Measures the current absorbed by the power amplifier
• Measures temperature
• Filters the pass low of the output RF signal
This board also features an RF sampling of approximately -13dBm RF with respect
to the output, which is available on a BNC connector below the transmitter output
connector. Sampling is useful for verifying the characteristics of the carrier, but
not for checking those of the upper harmonics.
9.4 Panel Card
This card is located in the front end of the device and provides an interface between
the CPU card and the remaining
PTX-DDS
cards.
This card handles all signals from/to LCD, Encoder, LED Indicators, Power Supply
Card, Audio Mainboard and external telemetry card, in other words, all input/output
signals of the CPU card.
The software denotes jumper positions as descripted in chapter. 5.2.8.
