R.V.R. Elettronica URP, Technical Manual

Page: 14 / 46

URP Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 14
VCO.
IC8B amplifies the input signal. Jumper JP2 is used when the user desired
single ended input.
With JP2 out of the circuit, the input is balanced. The output of IC8B
is sent to IC8A. With capacitors C63 and C64 in the circuit, pre-emphasis
is applied.
The insertion of these capacitors is controlled by the stereo/mono switch
on the front panel. The output of IC8A is used to modulate the unit in
the line selection.
In the microphone selection the signal from IC8B is further amplified
in IC9B and IC9A. IC10A and IC10B are used to rectify the audio signal
and process it for a deviation meter reading.
2.4 POWER AMPLIFIER BOARD
The power amplifier board receives the RF signal from the VCO board
at a level of 1.5 to 2 watts.
In the URP this signal is amplified by Q1 to ten watt level with the
high/low switch (4 Fig.1) on the front panel shorting out the collector/
emitter junction of Q2. When the high/low switch is open, transistor Q2
lower the voltage to Q1 and thus lowers the output power.
The amaplified signal is then sent through a low pass filter to remove
the harmonic content, then sent to the VSWR circuit where the power is
sampled for the front panel meter reading.
Only the direct power is measured on the front panel.