Ericsson NPC-50 Manual do Utilizador descarregar pdf (Página 3)

GENERAL

The NPC-200 VHF Portable Radio Unit operates in the

148-174 MHz frequency band with a power output of 5 or 1

watt (selectable). It has programmable features that permit a di-

verse range of features for the user.

The NPC-200 UHF Portable Radio Unit operates in the

438-470 MHz frequency band with a power output of 4 or 1

watt (selectable). It has programmable features that permit a di-

verse range of features for the user.

General operating procedures are contained in the applica-

ble Operator’s Manual.

CIRCUIT DESCRIPTION

The NPC-200 Portable Radio Unit Block Diagram is

shown in Figure 1. The radio consists of the following boards.

• Main

The receiver and transmitter sections, logic section and

regulators.

• Sub

The microphone amplifier, pre-emphasis and limiter,

microphone mute circuit, low pass filter, 2-tone decoder

and CTCSS bandpass filter.

• RF

The first RF amplifier and first mixer sections of the

receiver.

• VCO

Two voltage controlled oscillators for the receiver and

transmitter.

• PLL

The phase locked loop with a prescaler, reference crystal

oscillator and charge pump circuit.

• Switch

The transmit harmonic filter and antenna switch.

SYNTHESIZER

The synthesizer produces a stable RF frequency that is the

transmit frequency in the transmit mode and the receive first

local frequency in the receive mode.

The synthesizer consists of a phase locked loop (PLL) with

a prescaler, a reference crystal oscillator, a voltage controlled

oscillator (VCO), a transmit local oscillator and a charge pump

circuit.

When the operating channel of the radio is changed, the

microprocessor IC601 provides PLL IC301 with channel fre-

quency information. IC301 has three counters, a fully program-

mable reference counter, "N" and "A" counters. IC601-13 sup-

plies serially 16-bit and 19-bit of data to IC301-10. IC601-14

supplies clock pulses to IC301-9. IC601-49 supplies latch en-

able pulse to IC301-11. The appropriate counter latch receives

this data according to the last data bit (control bit) of each data

string entered.

The 12.8 MHz reference oscillator frequency (X301) is di-

vided by the reference counter. The dividing ratio is 1/2560 &

1/2048 for 5 kHz or 6.25 kHz channel step (VHF) or 1/1024

for 12.5 kHz channel step (UHF). The internal prescaler di-

vides the VCO frequency supplied to the PLL into a kHz-order

frequency. The resulting frequency is then divided by the "N"

and "A" counters. The internal phase detector circuit compares

the output of the reference counter to the output of the "N" and

"A" counters and issues error signals at pins 15 and 16. These

error signals pass through the charge pump circuitry (Q301)

and force the VCO frequency higher or lower until a LOCK

condition occurs.

The VCO circuit consists of Q201 for the receiver, Q204

for the transmitter and Q202 for the buffer-amplifier. Q203 en-

ables the receive VCO in the receive mode while Q205 enables

the transmit VCO in the transmit mode.

The VCO output signal enters the phase detector (pin 8 of

IC301) through a buffer-amplifier Q302 and keeps it phase so

no frequency changes are detected. The internal phase detector

of the PLL IC senses a phase difference between the divided

VCO frequency and the reference oscillator frequency. A logi-

cal low level is set at pin 7 of IC301 to indicate an out-of-lock

condition of the PLL. This signal is sent to the transmit inhibit

circuit through inverters Q303 and Q504. When the PLL is in

the locked condition, pin 7 of IC301 is set to a logical high.

The synthesizer frequency stability over temperature is

maintained within ± 5.0 PPM between -30°C and +60°C.

The transmit audio signal and the transmit sub-audible sig-

nal are applied to the variable capacitor diodes (D202 through

RT202 and RT201 in the VCO section and D302 in the PLL

section). RT202 adjusts the maximum deviation and RT201 ad-

just a balance of modulation between the VCO and the refer-

ence oscillataor. CT301 in the PLL section adjusts the

oscillation frequency of X301.

In the receive mode the VCO oscillates 59.85 MHz below

the receive frequency. The receive mixer circuitry produces the

first IF frequency (59.85 MHz) from the received signal and

the receive local frequency (VCO output).

SPECIFICATIONS*

VHF GENERAL

Regulatory Approval

FCC AMWUL087

DOC 287 195 103

Channels 16

Frequency Range 146-174 MHz

Channel Spacing 30 kHz (5 kHz/6.25 kHz step programmable)

Size 144 mm (H) x 60 mm (W) x 45 mm (D)

Weight 460 grams

Operating Temperature -30°C to +60°C

VHF TRANSMITTER

Output Power 5.0 or 1.0 Watt (selectable)

Frequency Stability ± 3 PPM

Spurious Emission -65 dBc

Hum and Noise 40 dB

Maximum Deviation ± 4.5 kHz (@100 mV input with CTCSS tone)

VHF RECEIVER

Sensitivity (12 dB SINAD) 0.25 µV

Squelch Sensitivity 0.15 µV

Intermodulation Rejection 70 dB

Spurious Response 80 dB

Adjacent Channel Selectivity 73 dB

Hum and Noise 42 dB

Audio Frequency Response +6 dB at 500 Hz, -6 dB at 2000 Hz @ 1 kHz reference

UHF GENERAL

Regulatory Approval

FCC AMWUL086

DOC 287 195 102

Channels 16

Frequency Range 438-470 MHz

Channel Spacing 25 kHz (12.5 kHz step programmable)

Size 141 mm (H) x 60 mm (W) x 45 mm (D)

Weight 460 grams

Operating Temperature -30°C to +60°C

UHF TRANSMITTER

Output Power 4.0 or 1.0 Watt (selectable)

Frequency Stability ± 3 PPM

Spurious Emission -65 dBc

Hum and Noise 40 dB

Maximum Deviation ± 4.5 kHz (@100 mV input with CTCSS tone)

UHF RECEIVER

Sensitivity (12 dB SINAD) 0.25 µV

Squelch Sensitivity 0.15 µV

Intermodulation Rejection 70 dB

Spurious Response 80 dB

Adjacent Channel Selectivity 70 dB

Hum and Noise 42 dB

Audio Frequency Response +6 dB at 500 Hz, -6 dB at 2000 Hz @ 1 kHz reference

* These specifications are intended primarily for use of the service technician. Refer to the appropriate Specifications

Sheet for the complete specifications.

AE/LZB 119 1658 R1A

1 2 3 4 5 6 7 8 ... 53 54

Comentários a estes Manuais

Sem comentários

Ericsson NPC-50 Manual do Utilizador Página 3

Comentários a estes Manuais

Manuais e produtos relacionados com não Ericsson NPC-50