Motorola T2260, Руководство по обслуживанию

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7 4/3/01
Preface
SHARK RF CIRCUIT
The RF circuit is very similar to CALIBER product, The Dual-Band
CDMA SHARK contains two completely separate receiver paths: an 800 MHz path that converts
analog signals and a 1900 MHz path for the digital CDMA signal. The two paths have different
RF, LO and IF frequencies.
In shark there is no accessory port for RF from the butt plug. To perform RX and TX test attach
the special cable to the RF test point on the back side near the antenna, remove the groumet.
Frequency of operation and channel
1900 Mhz Receiver Band 1930 to 1990 Mhz
1900 Mhz Transmitter Band 1850 to 1910 Mhz
The maximum output power applied to the antenna is:
Analog: 24.5dBm
PCS CDMA: 23.5dBm
Shark uses the ME3C mixer-exciter IC rather than the MOON IC part.
The ME3C allows full control of the RF power range from –39 dBm to +11dBm without having to
vary the ZIFSYN output power. The ME3 requires two LO’s, one for PCS, the other for analog.
The IF input pins are the same regardless of analog/PCS. There is one enable pin for the ME3C,
one pin for analog/PCS mode, and one for AGC pin. The two separate RF mixer outputs are
combined and drive to exciter. The ME3C PCS does require an interstage RF filter between the
Mixer and the exciter, but AMPS mode doesn’t require an interstage RF filter.
Shark uses DUAL BAND VCO Module for main LO, 14 pin part with two outputs one for AMPS
and another for PCS, the control voltage from ZIFSYN IC varies from 0.5 V to 2.2 V, the VCC to
the IC is supplied by the VSF 1900 and VSF 800. The output is split into RX_LO and TX_LO for
both AMPS and PCS LO.
The rest of the RF circuit is similar to DUAL BAND Caliber product.