User Guide

2115i/2116/2116i (RH-66)

RF Description and Troubleshooting

19.2 MHZ VCTCXO Reference Clock

The VCTCXO frequency is a 19.2 MHz reference signal. Without 19.2 MHz, the mobile

terminal does not power up. This signal goes to N7100, N7000, UHF PLL, and the UPP. Use

a high impedance probe to check for the presence of the signal at the following points:

• F_REF_TX, clock reference to N7000, should be ~ -9 dBm

• F_REF_RX, clock reference to N7100, should be ~ -9 dBm

• CLK19M2_UPP, clock reference to UPP, should be ~ -9 dBm and ~2 dB less in the

other side on R517

If you do not see the VCTCXO signal at any of these points, check to see if there is

voltage at the following points:

• VR3, main supply line for VCTCXO circuitry, should be 2.78 VDC

• AFC voltage, should be between 1 and 3 V, and should be adjustable with the AFC

slider on the RF PDM Control dialog box in Phoenix. If the AFC voltage is

missing, check the UEMC.

Measuring the AFC Voltage

1. Measure the DC voltage at R7205.

Figure 21: AFC voltage measurement location at R7205