Radio Shack Pro-60 User manual

Radio /hack
Service
PRO-60
PROGRAMMABLE SCANNER
Catalog Number: 20-309/9309
CONTENTS
Page
Specifications.2
Block Diagram.4
Theory of Operation.5
General Operation Outline. 6
Reception Check.8
Alignment and Adjustment. 9
Troubleshooting. 15
Printed Circuit Boards. 18
Wiring Diagram.21
Exploded View.22
Mechanical Parts List. 23
Electrical Parts List. 24
Semiconductor Lead Identification.47
Microprocessor (1C 1) Port Format. 5 2
Schematic Diagram.53
© 1995 Tandy Corporation.
All Rights Reserved.
Radio Shack is a registered trademark used by Tandy Corporation.
20-309/9309

SPECIFICATIONS
Frequency coverage
30 MHz-87.495 MHz
5 kHz steps
87.5 MHz-107.950 MHz
50 kHz steps
-
108 MHz-136.975 MHz
25 kHz steps
137 MHz-224.995 MHz
5 kHz steps
225 MHz-399.9875 MHz
12.5 kHz steps
400 MHz-512 MHz
12.5 kHz steps
*1
760 MHz-824 MHz
12.5 kHz steps
*1
849 MHz-869 MHz
12.5 kHz steps
‘1 894 MHz-999.9875 MHz
12.5 kHz steps
*1 760 MHz -999.9875 MHz for 20-9309
—
Unit Nominal
Limit
Sensitivity
NFM: (S+N)/N=20 dB 30-512 MHz
pV
1 2
Dev.: 3 kHz at 1 kHz 760-999.9875 MHz
pV
1 3
AM: (S+N)/N=20 dB
30-512 MHz
pV
2 5
—
Mod. 60% at 1 kHz
760-999.9875 MHz
pV 2 5
WFM: (S+N)/N=30 dB 30-512 MHz
pV 3 10
Dev. 45 kHz at 1 kHz
760-999.9875 MHz
pV 3 10
Squelch sensitivity
NFM and AM
Threshold
pV 0.5
2
Tight
dB
25 15
—
WFM
Threshold
pV
3 10
Tight
dB
40 30
Spurious rejection
at 328 MHz (NFM)
dB
40 30
_
(except primary image)
Modulation acceptance (EIA
. RS-204-A)
—
NFM
kHz
±8 ±5
WFM
kHz
±150 ±75
—
Signal to noise ratio
NFM
Dev.: 3 kHz at 1 kHz
30-512
MHz
dB 40
30
—
Input 100 pV
760-999.9875 MHz
dB 35
25
AM
Mod.: 60% at 1 kHz
30-512 MHz dB
40 30
Input 100 pV
760-999.9875
MHz dB
40 30
—
WFM
Dev.: 45 kHz at 1 kHz
30-512
MHz dB 50
35
i
Input 100 pV
760-999.9875
MHz
dB
50 35
— 2 —

Unit
Nominal
Limit
Residual noise
Volume control, set to its minimum, squelched
mV
3
5
Scanning rate
channels/sec.
25
22-28
Search rate
steps/sec.
50
47-53
Priority sampling
sec. 2
1-3
Scan delay time
sec. 2
1-3
Audio output power
10% THD
mW
180
150
Current drain
Squelched
mA
100
115
Channels of operation
Channels, frequency,
and mode display
Receiving system
Power source
Jacks
Dimensions (HWD)
Weight
Any 200 channels in any b~nd combination
Liquid crystal display
Direct key entry digital-control synthesizer,
1st IF: 608.005-611.2 MHz
2nd IF: 45 MHz
3rd IF: 10.7 MHz (WFM), 455 kHz (NFM/AM)
9 V DC negative ground only
6 AA batteries or a suitable adapter
Antenna, earphone, external power, and charge
5 7/8x2 1/4 x 1 3/4 inches (150 x 62 x 44 mm)
8.8 oz. (250 g) without antenna and batteries
Note: Nominal specs represent the design specs. All units should be able to approximate these—some will
exceed and some may drop slightly below these specs. Limit specs represent the absolute worst condition that
still might be considered acceptable: in no case should a unit fail to meet limit specs.
— 3 —

BLOCK DIAGRAM
Batteries

THEORY OF OPERATION
The PRO-60 is a PLL (Phase-Locked Loop) synthesized VHF/UHF, AM/FM receiver, controlled by a CPU (Central
Processing Unit) via a keyboard.
Receiving mode and search step are initially set to correspond with the frequencies entered. When a frequency
within the FM broadcast band is keyed in, the receiving mode is set to wideband FM (WFM). When a frequency in
the active radio band, such as police, fire, and ham radio, is keyed in, the mode is set to narrowband FM (NFM),
and when a frequency in the aircraft band is keyed in, it sets to AM mode. The mode can also be changed by the
AM/FM/WFM key.
All functions, such as the receiving frequency range, frequency determination, scanning an 1 delay time, etc. are
controlled by the CPU (IC1). The CPU is able to do only the assigned functions and no me' .cation of the CPU is
feasible.
The following paragraphs explain the operation of the circuit in terms of the functional blocks:
Varactor (variable capacitance diode) tuning (automatic tuning system) is employed on all bands.
The RF input circuit consists of the bandpass filters (BPF). A signal generated by VCOI or VC02 is applied to the
1st mixer and mixed with the RF signal. The 1st mixer is employed to facilitate 30 MHz to 999.9875 MHz mixing.
The 1st IF (Q106) is 608.005 - 611.2 MHz, and the signal is mixed with VC03 frequency at the 2nd mixer (Q107)
to produce a 45 MHz signal. Corresponding with the input from the keyboard, the CPU selects VCOI or VC02
and determines the AM/NFM/WFM data of the PLL circuit that will function; then it outputs the necessary data.
A signal entered to NFM/AM IF is mixed with crystal oscillation frequency 44.545 MHz at the 3rd mixer (IC301)
and converted to a 455 kHz signal. A signal entered to WFM IF is mixed with crystal oscillation frequency 34.3
MHz at the 3rd mixer (IC302) and converted to a 10.7 MHz signal. The signal is further amplified to be detected as
an AF signal.
The AF signal of AM, NFM, and WFM is CPU-controlled and applied to the AF power amplifier (IC306) via a
switching circuit. Squelch signals are comprised of noise products from detector output, and amplified by IC301
through a switching signal, which controls the AF mute and CPU.
CXI (4.19 MHz) is a clock which controls the CPU. Figure A shows the clock waveform at IC1 pin 58.
The unit has a battery-saving control in manual mode. When the unit is in operation, IC1 pin 61 is M H " and IC309
is on. If there has been no signal input or no key input for more than 5 seconds in manual mode with squelch on,
pin 61 goes "L" (Figure B), turning off IC309 to shut off the power supply for most of the circuits (except the CPU
and audio circuit). In this battery-saving mode, the unit uses only 40% of the power required for normal operation.
Any unstable supply voltage to the CPU can produce a CPU malfunction, such as wrong data processing, wrong
data transfer, etc. To overcome this, the CPU can be initialized when necessary. To initialize the CPU, press and
hold CLEAR and 0, and then turn on the power.
Figure A
Figure B

GENERAL OPERATION OUTLINE

1
2
Turn on the KEY LOCK switch so the keys will
not function except SCAN, MAN, and LIGHT.

RECEPTION CHECK
— 8 —

ALIGNMENT AND ADJUSTMENT
ALIGNMENT AND TEST POINTS
and Cl 88 (10 pF) are connected.
ALIGNMENT PREPARATION
Test Equipment Required
• Oscilloscope
• AC SSVM
• DC SSVM
• 8-ohm dummy load
• AM/FM signal generator
Notes:
• Use non-metallic tuning tools.
• The test equipment and receiver should be warmed up for at least 10 minutes before proceeding with align¬
ment.
• The signal level from the generator should be kept as low as possible to obtain a usable output.
• Distortion meter
• Frequency counter
Program channels 1 through 10 are as follows:
Table 1
Channel
Frequency and Band Mode
Channel
Frequency and Band Mode
1
512 MHz (NFM)
6
^ 155 MHz (NFM)
2
98 MHz (WFM)
7
225 MHz (NFM)
3
30 MHz (NFM)
8
126 MHz (AM)
4
760 MHz (NFM)
9
31.995 MHz (NFM)
5
999.9875 MHz (NFM)
10
32 MHz (NFM)
— 9 —

ALIGNMENT PROCEDURES
PLL2 VCO Alignment
Control Setting Test Instrument Connection
Adjust
Result
OFF/VOLUME control: ON.
SQUELCH control: Fully
counterclockwise (CCW).
Select channel 3.
Connect DC SSVM to TP103.
See Figure 1.
LI 28
Adjust LI 28 to 2.4+0.1 volts
on the DC SSVM. See Table 2.
PLL1 VCO Alignment
Control Setting Test Instrument Connection
Adjust
Result
OFFA/OLUME control: ON.
SQUELCH control: CCW.
Select channels 3 and 4.
Connect DC SSVM to TP102.
See Figure 2.
LI 25
1. Select channel 3 and adjust
LI 25 for 25.5±0.5 volts on
the DC SSVM.
2. Select channel 4 and be sure
the DC SSVM reads 0.8-3.0
volts (no adjustments are
necessary for the coil). See
Table 2.
DCSSVM DCSSVM
Figure 1 Figure 2
Ajustment of Coils LI 25 and LI 28
Each coil should be adjusted carefully by changing the pitch of the coil little by little by using a non-metallic tuning
tool as shown in Figure 3.
Squeeze the coil to increase the voltage and stretch the coil to decrease the voltage.
Notes:
• Be very careful when doing coil pitch adjustment be¬
cause it greatly affects the frequency.
• Secure the coil with glue after alignment. Be sure the
glue is dry and the coil is secured. Also, be sure that the
environmental temperature is normal. Then, repeat VCO
(PLL2 and PLL1) alignments above.
Figure 3
Coil
/-
Use
non-metallic
tuning tool
uumfj
RF PCB
Table 2
CH Frequency
Voltage
m
30 MHz
30 MHz
760 MHz
Voltage at TP103: 2.3-2.5 volts
Voltage at TP102: 25-26 volts
Voltage at TP102: 0.8-3.0 volts
— 10 —