R.V.R. Elettronica PTX-LCD, Руководство пользователя

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PTX-LCD
12 / 58 User Manual Rev. 2.3 - 18/07/07
possible to control all the working parameters of the device.
Specifically, before enabling the power output, we suggest to verify and in case to
correct according to your needs the fundamental parameters:
• frequency
• power
• audio input level
• audio input impedance
• preemphasys
• kind of audio input (depending on the version, MONO or MPX or MONO,
MPX_U, MPX_B, STEREO)
• if in STEREO mode, verify that pilot tone is enabled
If you disabled the power output, it is now possible to activate entering in the main
menu, selecting the first item and changing it from OFF to ON.
It is any time possible to disable the power output of the PTX-LCD, from the main
menu.
5.4 Adjusting
The PTX-LCD features some trimmers, accessible from the rear panel, that can
be adjusted to the user's needs. these are: two EXT AGC trimmers (FWD and
RFL) and the LEVEL ADJ (Fig. 6-2 [16]).
The LEVEL ADJ trimmers are used to adjust the modulation level due to the
respective input. For audio input, the levels are set via software with 1 dB steps,
and the trimmers can be used for fine setting.
For SCA input, the levels are only adjusted with the trimmers.
The EXT AGC trimmers give to the user the possibility to limit the outout power of
the transmitter as a function of the levels of two external analog values that are
acquired by the Remote connector.
Both trimmers work in the same way: EXT AGC - FWD is connected to pin 10 of
the Remote connector, while EXT AGC-RFL is connected to pin 2. If the voltage
connected to one of the pins tends to surpass the limit set with the corresponding
trimmer, the power emitted by the exciter is reduced until the monitored voltage
goes below the fixed limit.
These trimmers are mostly useful when the PTX-LCD is part of a transmission
system. For example, if the exciter is connected to a final amplifier it is practical to
connect to pin 10 a voltage that is proportional to the RF power emitted by the
amplifier, and to pin 2 a voltage proportional to the reflected power. In this way, it