Sailor RE2100, Техническое руководство

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3 SERVICE RE2100
The output level from signal generators in general is sometimes expressed in terms of the available power
P
a
, which is measured in terms of the unit: dBm = 10 log(P
a
/1mW), (dB above one milliwatt). For this
reason the conversion formulas between EMF and available power and vice versa are given here:
P
a
(dBm) = EMF (dB/uV) - 113 dB
EMF (dB/uV) = P
a
(dBm) + 113 dB
where P
a
is the available power and EMF is the Electromotive Force of the generator.
3.6.1 MODULE PERFORMANCE CHECK OF RECEIVER UNIT
This chapter contains the following sections:
3.6.1.1. Check of Sensitivity (RX-Module)
3.6.1.2. Check of LO2 and Reinjection Signals
3.6.1.3. Check of Crystal Filters (2nd IF)
3.6.1.4. Check of 2nd IF Amplifier
3.6.1.5. Check of AGC Circuit
3.6.1.6. Check of Detector
3.6.1.7. Check of AF Filters
3.6.1.8. Check of Earpiece Amplifier
3.6.1.9. Check of Squelch Circuit
3.6.1.1 CHECK OF SENSITIVITY (RX_MODULE)
The sensitivity of the receiver unit is mainly determined by the Second Mixer because of its relatively large
power gain of about 8 dB. It is therefore most likely that a degradation of the sensitivity is caused by the
mixer; but be aware that this is not the only possible failure.
A degradation of the sensitivity could also be caused by a failure in the IF-amplifier, detector, audio
frequency circuit, or simply by a missing local oscillator signal (LO2 or carrier reinjection).
To obtain a correct measurement of sensitivity, it is necessary to feed the generator signal through an
impedance matching network as shown below.
4-0-26211
Impedance matching between generator and receiver module.
1. Connect the generator to receiver module through the impedance matching network shown above.
2. Connect the voltmeter to earpiece output at testpoint TR2-1 for measuring the AC-voltage.
3. Turn the RE2100 on.
4. Choose generator frequency f
G
and generator output level V
G
as specified in point 6. Select the
wanted Receiver Module (SSB/AM).
5. Measure the signal to noise ratio SND/N at the earpiece output and check that it is above 20 dB.
(see section 3.5.2.1., point 6 for instructions about how to measure SND/N).
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