4. Adjust the attenuator as in step A-3 above, to
produce an adequate signal level to the service
monitor's receiver.
5.
Adjust the transmitter and follow the same pro-
cedure outlined in steps A-5 through A-7 above,
to measure frequency and deviation.
6.
This same method may be used to verify fre-
quency and deviation
of
a remotely located trans-
mitter by reducing the attenuator setting to fully
realize the 1.5uV
(10 dB SINAD) sensitivity
of
the service monitor's "of-the-air" monitor func-
tion. To insure sufficient measurement accuracy
however, make sure the Monitor receiver
is
fully
quieted as in step A-3 above.
C. Harmonic
Power Measurement (R-2400)
1.
Referring to Figure 5.6, insert a fixed power at-
tenuator between the RF output connector
of
the
transmitter
and
the "Antenna" port
of
the
R-2400. The power rating
of
this attenuator must
be at least equal
to
the rating
of
the transmitter,
and a minimum
of
30
dB attenuation. The input
power
to
the antenna port must not exceed 0.5
watt.
2.
Set the "Function" switch to "Sens
Mon/
Anlzr
On"
and enter the carrier frequency, as before.
3.
Observing the CAUTION above, with a fixed at-
tenuator in series, key the transmitter and set the
step attenuator for a peak indication on the spec-
trum analyzer between the REF and
-10
dB
graticules. Note the displayed level and the step
position in dB. De-key the transmitter.
4. Enter the frequency
of
the harmonic or spurious
signal
of
interest.
Key
the transmitter and
observe the level
of
the signal on the spectrum
analyzer, adjust the step attenuator
if
necessary,
should the signal be too low
to
observe. Confirm
that the signal changes
10
dB for a
10
dB change
in the step attenuator setting (See notes on page
5.2). Note the level
of
the signal and the step at-
tenuator setting, in dB. De-key the transmitter.
5.
Compute the level difference between the carrier
and the spur
/harmonic
as follows:
A. Let
"REF"=
0 dB, and step position
is
a nega-
tive number.
B.
PC=
displayed level
of
carrier-(step) ie.:
-3
dB-(-50
dB)=
+47
dB
C.
P1
=displayed level
of
spur-(step) ie.:
-22 dB-(
-30
dB)=
+ 8 dB
D. The relative difference between the carrier and
spur/harmonic levels
is
P
diff=PC-P1
=47-8
=39
dB.
5-6
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TRANSMITTER
FIGURE 5.
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TRANSMITTER AUDIO FREQUENCY
RESPONSE
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TRANSMITTER
FIGURE
5.8-
TRANSMITTER AUDIO DISTORTION
SETUP
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