Step 2. Local Oscillator Checking; Fig 17 Rf Test - Nokia RH-13 Series Troubleshooting Manual

RH-13
Troubleshooting

Step 2. Local oscillator checking

Carrying out this step VCO signal of 1st and 2nd mixers can be checked. 2nd mixer RX
VHF VCO frequency is constant 268.08 MHz but for the 1st mixer UHF VCO frequency
depends on the channel. The UHF VCO frequencies for the 1st mixer are:
Channel 991:
Channel 380:
Channel 799:
1 Set signal generator frequency to 881.4091125 and level to -80 dBm.
2 Set phone to TDMA mode and select RF Test UI in Phoenix (Maintenance => Test-
ing => RF Test).
3 Make sure that signal generator allows phone TX power going to its output. Use
low power level, for example 10. Set channel to 380 and select "Write Init".
4 Set spectrum analyzer settings as following:
• Center frequency: 268.08 MHz, Span: 200 kHz
• RBW: 3 kHz, reference level: 0 dBm
5 Connect spectrum analyzer probe on the inductor L818 and record RX VHF VCO
signal level and frequency. Signal level should be around -25 dBm and frequency
268.08 MHz.
6 Set spectrum analyzer settings as following:
• Center frequency: 2030.88 MHz, Span: 200 kHz
Page 34
2006.16 MHz
2030.88 MHz
2056.02 MHz
Figure 17: RF Test.
ãNokia Corporation
CCS Technical Documentation
Issue 1 11/02