User Guide

CCS Technical Documentation Troubleshooting — RF
RH-17
Issue 1 04/2003 Nokia Corporation Confidential Page 29
is present but tone at 836.52 MHz is not, troubleshoot CDMA TX chain as described in
Tables 2 and 3.
If the carrier is present but it cannot be centered, there is a hardware problem. Check
Table 7.
In the following procedure, performing frequency centering on the RF carrier at 836.52
MHz will detect frequency errors due to the VCTCXO and supporting hardware, which
will be the majority of the problems, but will not detect frequency errors due to the
hardware that uses VCTCXO tone at 19.2 MHz as a reference for VHF PLL's. Check then
the VHF and UHF LO's should be at correct frequency. Since this will be time consuming
and will probably only account for a small percentage of the failures, it is not recom-
mended unless the situation justifies the time spent. The VHF LO is inside the Robin IC
(N601) and troubleshooting of the cell UHF LO is according to Table 5.
If the carrier cannot be centered, check to see if you can adjust to 2.2v on pin 1 of G501.
If you can, within the PDM range of +/- 150, then the circuitry that delivers the voltage
is working correctly, and the VCTCXO has a problem. Troubleshoot it as described in the
previous section. If you cannot adjust to 2.2v within the accepted range, then the AFC
circuitry has a problem. Troubleshoot it as described in the previous section.
In the case that there is a fault with both the AFC circuitry and the VCTCXO, then several
combinations of the previously described conditions are possible. Start by ensuring 2.2v
on pin 1 of G501 using a PDM within the range +/- 150, then center the tone.
Test 40 - 44 TN TX IF AGC Cell Po (0) [or (1), (2), (3), (4), (5), (6)]
Description:
The IF gain curve is characterized by varying the TX_IF_AGC and measuring the transmit
power.
Explanation of Result:
The results are TX power readings in dBm of the transmitted signal corresponding to
given PDM settings of the Cell TX IF AGC.
C) Manual Verification:
Set the phone in local mode, then program it to Cell CDMA RX/TX mode on channel 384.
Set modulation to IS95 voice in CDMA Control.
Set the Cell PA PDM to +218 decimal and the TX RF AGC to -512 decimal using the slid-
ers in the PDM window under the RF menu.
Change the TX_IF_AGC to the settings in the following table, and measure the TX power
levels, checking to see that they are within the specified range.