R.V.R. Elettronica RXRL-NV, Техническое руководство

Страница: 36 / 204

RXRL-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 36
3) Gradually reduce the level of the injected R.F. signal continuing
to adjust for the maximum 10.7 MHz IF signal level.
Repeat this operation until the injected signal level is less than
-47 dBm (1mV).
4) With an R.F. input level of -47 dBm, having adjusted the compensators
on the Front-end Mixer, check that the 10.7 MHz IF signal level is
approx. 100-150 mVpp.
5) To execute a more precise adjustment, decrease ulteriorly the R.F.
input signal (until -67 dBm).
5.3 CALIBRATION OF THE 70MHz IF STAGE
To carry out this procedure, configure the unit as detailed in
SETUP1:
1) Use an R.F. signal generator to inject a -47 dBm signal into the
R.F. input of the receiver.
2) Using a frequency meter, check the accuracy of the 10.7 MHz IF
(10.700 MHz is acceptable).
Adjust if necessary using compensators C15 and C16 situated on the
PLL card.
3) Using an oscilloscope, adjust TR1 and then TR2, situated on the card,
to maximize the 10.7 MHz IF signal level.
4) Check that the amplitude of the 10.7 MHz IF signal is still > or
= 150 mVpp, and if not, adjust P1 accordingly (take care adjusting
P1 not to increase distortion levels).
5) Now configure the receiver as detailed in SETUP2 (Fig.5).
6) Inject a 400 Hz tone into the R.F. generator and modulate it with
a deviation of ±75 KHz. The resultant output should be fed to the
R.F. input of the receiver.
7) Check that the MONO (R42) and STEREO (R41) trimmers, situated on
the front panel, are in their maximum position.
SETUP 2