Notes For All Schematics and Circuit Boards
5.0
Notes For All Schematics and Circuit Boards
* Component is frequency sensitive. Refer to the Electrical Parts List for value and usage.
Unless otherwise stated, resistance values are in ohms (K = 1000), capacitance values
1.
are in picofarads (pF) or microfarads (µF), and inductance values are in nanohenries
(nH) or microhenries (µH).
DC voltages are measured from point indicated to chassis ground using a Motorola DC
2.
multimeter or equivalent. If the board has been removed from the chassis, the transmitter
module mounting screws may be used for ground connection. ( Note: The antenna nut
bracket is not connected to ground. ) Operating mode dependent voltages are followed by
(RX) for receive mode, (TX) for transmit mode, (UNSQ) for unsquelched mode, etc.
RF voltages on VHF models are measured with a Fluke model 85 RF probe. The
3.
indicated voltages expressed in mV (RF) are DC level readings which correspond
approximately 1:1 to the RF voltage level in mV rms. RF voltages in the Receiver Front
End and Receiver Back End circuits are measured with an on-channel 100 mV (-7 dBm)
RF signal applied to the antenna jack J140.
RF voltages on UHF models are measured both with a high-impedance RF voltmeter
4.
having a bandwidth in excess of 500 MHz (levels are expressed in dBm) and with a Fluke
model 85 RF probe [levels are expressed in mV (RF)]. These indicated voltages are DC
level readings which correspond approximately 1:1 to the RF voltage level in mV rms,
and are only approximate for UHF frequency measurements. RF voltages in the Receiver
Front End and Receiver Back End circuits are measured with an on-channel 100 mV (-7
dBm) RF signal applied to the antenna jack J140.
Audio voltages are measured with a high-impedance AC rms voltmeter. The indicated
5.
voltages are expressed in mV rms. Receive mode voltages are followed by (RX) and are
measured with an on-channel signal with 1 kHz modulation at 60% deviation (3 kHz for
25 kHz channels, or 1.5 kHz for 12.5 kHz channels). Transmit mode voltages are
followed by (TX) and are measured with a 1 kHz, 10 mV rms signal present at the
external microphone input (accessory connector J471 pin 4 hot and pin 7 ground).
Reference Designators are assigned in the following manner:
6.
Ref. No. Series
1-99
RF Front End
100-149
Transmitter RF Stages
150-200
Transmitter Power Control
201-250
Frequency Synthesizer
251-300
VCO
301-400
DC Regulation
401-450
Microprocessor
451-550
Audio
Circuit Block
2-5
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