R.V.R. Elettronica PTRL-NV/2/S3, Техническое руководство

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R.V.R. ELETTRONICA S.r.l. (BO) Pag. 44
PTRLNV/2/S3 and PTRL-NV/2/HP/S3 - Technical and Maintenance Manual
2) Switch on the tranmitter and wait until it has locked to its
operating frequency and the UNLOCK light goes out.
3) Connect a 30dB attenuator between the R.F. Output and Frequency
Counter.
4) Use the meter selector to select direct power measurement, FWD.
Check that maximum output power.
5) Using the frequency meter, check the output frequency of the
transmitter and adjust as necessary with capacitors C68 and C69
situated on the Main card.
6) Connect the two units (TX and RX) as shown in SETUP A2 (Fig.8).
7) Adjust the variable attenuator for a value dependent from the
transmitter's output power (Table E).
8) Connect the counter to the IF 10.7 MHz output and check that the
frequency corresponds to this value, adjusting as necessary with
capacitors C27 and C28 situated on the Synthetizer card for a
frequency of 10.700 MHz ±2 KHz.
6.3 MEASUREMENT OF RECEIVER'S S/N RATIO
The mono S/N (signal to noise) ratio is measured at the output of
the receiver by feeding it with a 400 Hz modulating signal (±100 KHz
deviation) and comparing the output with the same output, under the same
conditions, in the absence of the modulating signal, across the 30Hz/
20 KHz band.
In the case of stereo modulation, the S/N ratio will be measured on single
channels (left and right) decoded and de-emphasized.
Both mono and stereo measurements should be taken having configured the
unit according to SETUP B1 and B2 and carrying out the following
procedure:
1) Connect the instruments as shown in SETUP B1 (Fig.9) to make MONO
measurement.
SETUP A2 / FIG. 8