Figure 3-9. Receiver Block Diagram (Vhf / 7/800) - Motorola APX 7000 Detailed Service Manual

Theory of Operation: Transceiver Board
3.1.2 Receiver
The RF signal is received at the antenna and is routed through the Auxiliary and Multi Switch (SP3T)
ICs. The latter contains a switchable 15 dB attenuator that is enabled at predetermined RF power
thresholds present at the antenna port. The output of the Multi-switch IC is applied to the first SPST
band select switch to select the desired RF band.
• VHF or 7/800 bands (for VHF / 7/800 radios.
• UHF1 or 7/800 bands (for UHF1 / 7/800 radios.
• UHF1 or VHF bands (for UHF1 / VHF radios.
• UHF1 or UHF2 bands (for UHF1 / UHF2 radios.
• UHF2 or 7/800 bands (for UHF2 / 7/800 radios.
• UHF2 or VHF bands (for UHF2 / VHF radios.
AUX
GPS
PER SW
DPLXR
SP3T 2:1
*
* Kit below rev E
does not have
SAW filter
To
RF/Vocon
Connector

Figure 3-9. Receiver Block Diagram (VHF / 7/800)

See Figure 3-9.)
See Figure 3-10.)
See Figure 3-11.)
See Figure 3-12.)
See Figure 3-13.)
See Figure 3-14.)
700/800
VHF
2nd
LO
SW
2:1
SSI
ΣΔ ADC Dec.
Filter
18Mhz
LO CLK
CLK
Abacus III
3-9