Nokia RM-57, Руководство по обслуживанию

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BT antenna
BT antenna has one Feed and two GND contacts. The antenna is functioning normally when the contacts function
(RDC = 0 ohm) and the antenna is visually intact.
Figure 68 BT antenna
RF tuning
Introduction to RF tunings
Phone RF is tuned in production. There is no reason to do the re-calibration unless:
• One or more of the RF components is changed
• FLASH Memory chip (D3000) is changed or otherwise corrupted.
Note: RF calibration is always performed with the help of a product-specific module jig, never with
an RF coupler. Using an RF coupler in the calibration phase will cause a complete mistuning of the RF
side.
Important: After RF component changes, autotuning is recommended. RF autotuning covers all
necessary tunings which are required after RF component repairs.
Cable and adapter losses
RF cables and adapters have some losses. They have to be taken in account when the phone is tuned. As all the
RF losses are frequency dependent, the user have to be very careful and understand the measurement setup.
In the following table there are RF attenuations of the module jig:
Band Attenuation
GSM850/GSM900 0.2 dB
GSM1800 0.3 dB
GSM1900 0.3 dB
RF autotuning
Before you begin
For information on the recommended test set-up, refer to the corresponding information on PWS/NOL.
Before you can use the auto-tune feature, the GPIB driver from the GPIB card vendor must be installed and
running.
RM-57/58
Nokia Customer Care RF Troubleshooting and Manual Tuning Guide
Page 7–14 Company Confidential Issue 1
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