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

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RXRL-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 41
5) Inject a carrier at the receiver’s operating frequency, modulated
by a 400 Hz tone with 7,5 KHz deviation.
6) Adjust trimmer R4, situated on the Modmeter card, so that the first
red led switches on (corresponding to the 100% mark).
5.9 CALIBRATION OF THE POWER SUPPLY
This module does not require calibration.
5.10 CALIBRATION OF THE VCO
To calibrate the VCO, carry out the following procedure:
1) Connect the positives probe of a voltmeter to the glass capacitor
P2 (connected to the varicap) and the negative probe to ground.
2) Check that at both limits of the operating frequency band (defined
by the EPROM), the voltage reading lies between 3.5 and 10.3V.
The highter frequency should correspond to the highter voltage and
vice versa.
3) If the voltages in step 2. cannot be verified and the PLL is not
locked, the soldered joint, connecting the SL strip-line to ground,
should be moved (the other end of the strip-line is connected to
the cathode of the varicap via capacitor CX).
4) Should the chosen operating frequency be less than 500 Mhz, the
strip-line will have been replaced by a piece of 50 Ohm teflon cable
(RG 316).
In this case the varicap voltage mey be adjusted by varying the
length of the cable accordingly.
The central conductor is shorted to the screen at one end of this
cable.
5) If the calibration procedure is being carried out after a change
of frequency, capacitor CX, situated on the VCO card, will also have
to be changed according to table D.