Tandy Realistic PRO-43 User manual

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PRO-43
PROGRAMMABLESCANNER
Catalog Number: 20-300/9300
CONTENTS
Page
Specifications ..........................................................................2
Block Diagram 4
Principles of Operation ...................................................................5
GeneraJOperation Outline .......................................................... 6
AlignmentiAdjustment 8
Reception Check 16
Troubleshooting
.. ................................................................... .. 17
Wiring
Diagram. ..................................................................... .. 19
Printed Circuit Boards 20
Electrical Parts
List. .................................................................... 23
Mechanical Parts List 38
Disassembly/Exploded View 39
Semiconductor Lead Identification and IC Block Diagram 40
Microprocessor (IC1) Port Format 48
Schematic Diagram 51
©1992 Tandy Corporatlon.
All Rights Reserved.
Radio Shack and Realistic are registered trademarks used by Tandy Corporation.

SPECIFICATIONS
Frequency Coverage
VHFLOW
*1 30 MHz - 54 MHz 5 kHz steps
VHF AIRCRAFT 118 MHz - 136.975 MHz 25 kHz steps
VHF HIGH-1 137 MHz - 174 MHz 5 kHz steps
VHF HIGH-2 220 MHz - 225 MHz 5 kHz steps
VHF HIGH-3 225.0125 MHz - 350 MHz 12.5 kHz steps
UHF LOW 350.0125 MHz - 512
MHz
12.5 kHz steps
UHF HIGH *2 806 MHz - 823.9375 MHz 12.5 kHz steps
851 MHz - 868.9375 MHz 12.5 kHz steps
896 MHz - 999.9875 MHz 12.5 kHz steps
*1 68 - 88
MHz tor 20-9300
*2 806 - 960 MHz tor 20-9300
Unit Nominal Limit
Sensitivity
FM: (S+N)/N=20 dB 30 MHz - 54 MHz JlV 1.0 2.0
DIV.: 3 kHz at 1 kHz 118 MHz - 136.975 MHz JlV 1.0 2.0
137 MHz - 174 MHz JlV 1.0 2.0
220 MHz - 225 MHz JlV 1.0 3.0
225.0125 MHz - 350 MHz
JlV 1.0 3.0
350.0125 MHz - 512 MHz JlV 1.0 3.0
806 MHz - 999.9875 MHz JlV 1.0 3.0
AM: (S+N)/N=20 dB 30 MHz - 54 MHz JlV 2.0 5.0
MaD.: 60% at 1 kHz 118 MHz - 136.975 MHz JlV 2.0 5.0
137 MHz - 174 MHz JlV 2.0 5.0
220 MHz - 225 MHz JlV 2.0 5.0
225.0125 MHz - 350 MHz JlV 2.0 5.0
350.0125 MHz - 512 MHz JlV 2.0 5.0
806 MHz - 999.9875 MHz JlV 2.0 5.0
Squelch Sensitivity at threshold JlV 1.0 3.0
at tight (S+N)/N (FM) dB 30 15
at tight (S+N)/N (AM) dB 20 10
Spurious Rejection at 328 MHz (FM) dB 40 30
(except primary image)
Modulation Acceptance (EIA RS-204-A) kHz ±8 ±5
Signal to Noise Ratio
FM: 30 MHz - 54 MHz dB 40 30
118 MHz - 136.975 MHz dB 40 30
137 MHz -174 MHz dB 40 30
220 MHz - 225 MHz dB 40 30
225.0125 MHz - 350 MHz dB 40 30
350.0125 MHz - 512 MHz dB 35 25
806 MHz - 999.9875 MHz dB 35 25
AM: 30 MHz - 54 MHz dB 40 30
118 MHz - 136.975 MHz dB 40 30
137 MHz - 174 MHz dB 40 30
220 MHz - 225 MHz dB 40 30
225.0125 MHz - 350 MHz dB 40 30
350.0125 MHz - 512 MHz dB 35 25
806 MHz - 999.9875 MHz dB 35 25
Note: RF Input 100 JlV, Mod. 60% at 1 kHz
-2-

5
22 - 28
47 - 53
1 - 3
1 - 3
150
180
8
100
3
25
50
2
2
180
250
3
85
(Vol. Min., Squelched)
Squelched
T.H.D.10%
Max.Power
mV
channels/sec
steps/sec
sec
sec
mW
mW
%
mA
Any 200 channels in any band combination
Liquid Crystal Display
Direct Key Entry Digital-Controlled Synthesizer, Superheterodyne
1st IF: 608.005 MHz - 611.2 MHz
2nd IF: 48.5 MHz
3rd IF: 455 kHz
9 Volt DC negative ground only
6 AA Batteries or a suitable adapter
Test to specification between +64°F and +9s
oF
(+18°C and +3S
0C)
5 3/4(H) x2 3/4(W) x1 S/8(D) inches (145 x58 x42 mm)
8.8 oz. ( 250 g) without anten na and batteries
Residual Noise
Scanning Rate
Search Rate
Priority Sampling
Scan Delay Time
Audio Output
T.H.D. at 50 mW
Current Drain
Channels of Operation
Channels, Frequency, and Mode Display
Receiving System
Power Source
Temperature Range
Dimensions
Weight
Note: Nominal specs represent the design specs. All units should be able to approximate these---some will ex-
ceed and some may
drop slightly below these specs. Limit specs represents the absolute worst condition that
still might be considered acceptable; in no case should a unit fail to meet limit specs.
-3-

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PRINCIPLES OF OPERATION
The PRO-43 is a Phase Locked Loop (PLL) synthesized VHF/UHF, AM/FM receiver, controlled by a Central Pro-
cessing Unit (CPU) via a keyboard.
Receiving mode and search step are initially set to correspond with the frequencies entered. When a frequency
in active radio band, police, fire, ham radio, etc. is keyed in, the mode is set to FM and when a frequency in air-
craft band is keyed in, the mode is set to AM. The mode can also be changed by the AM/FM key.
All functions, such as the receiving frequency range, frequency determination, scanning and delay time, etc, are
controlled by the CPU (IC1). The CPU is able to do only the assigned functions and no modification of the CPU
is feasible.
The following paragraphs explain the operation of the circuit in terms of the functional blocks:
Varactor (variabie capacitance diode) tuning ("automatic tuning system") is employed on all bands.
The RF input circuit consists of bandpass filters (B.P.F.). A signal generated by VC01 or
VC02 is applied to the
1st mixer and mixed with the RF signa!. The 1st mixer is employed to facilitate 30 MHz to 999.9875 MHz mixing.
The 1st IF (0108,
0109) is 608.005 - 611.2 MHz, and the signal is mixed with VC03 frequency at the 2nd mixer
(0110) to produce a 48.5 MHz signal, which is applied to the 2nd IF (0301). Corresponding with input fram the
keyboard, the CPU selects VC01 or
VC02 and determines the AM/FM data of the PLL circuit that will function;
then it outputs the necessary data.
A signal entered to IF is mixed with a crystal oscillation frequency of 48.045 MHz at the 3rd mixer (IC301) and
converted to a 455 kHz signa!. The signal is further amplified to be detected as an AF signa!.
The AF
signalof AM and FM is CPU-controlled and applied to the AF power amplifier (IC304) via a switching cir-
cuit. Squelch signals are comprised of noise produets from detector output, and amplified by IC301 through a
switching signal, which contraIsthe AF mute and CPU.
CX1 (4.19 MHz) is a clock which contraIs the CPU. Figure B shows the
doek waveform at Pin58 of IC1.
The unit has battery-saving control in manual mode. When the unit is in operation, Pin61 of IC1 (CPU) is "H" and
IC307 is on. If there has been no signal input or no key input tor more than 5 seconds in manual mode with
squelch on, Pin74 goes "L" (Figure A), turning off IC307 to shut oft the power supply for most of the circuits (ex-
cept the CPU and audio circuit). In this battery-saving mode, the unit uses only about 30% 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.
ICI
Pin58 Pin59
5sec
H~---------I
Pin61
L -----------------
II
0.25sec
'-----+---VDD
1
Figure A
-5-
Figure B

GENERAL OPERATION OUTLINE
Turn on power SW.
Automatically sets the mode to SCAN and
starts scanning when
sa is on. When battery voltage drops, everything on the LCD
blinks, and peep tones sound from the speaker.
SCAN BANKS 1 through 10 are displayed. If
there is any blank scan bank, press the number
key to light all scan banks, and to blink one of
them in one after another. 1
Press keys [1] through [9]. SCAN BANKS 1 To hold the channel, press [DELA
Y] (when this
through 9 wil! disappear. channel is not set to [DELAY]).
1
Press [0]. No response. ITo release the delay function, press [DELA
Y] again. I
1
Press keys [1] through [9] and [0]. SCAN To skip a certain frequency, press [UOUT] (when this
BANKS 1through 9 are displayed, but not 10. channel is not set to [UOUT]).
1
To release the lockout function, press [UOUT] again.
To obtain priority operation in scan mode,
press [PRI]. 1
To obtain priority operation in manual mode, press
To release the priority function in scan mode, [PRI].
press [PRI] again. 1
To release the priority function, press [PRI] again.
Press [MANUAL]. When [MANUAL] is pressed
again, the channel advances. To select one of l
1 through 400 channels, press the number key
and then press [MANUAL]. Press [PGM] to turn on program mode.
To start direct search, press [DIRECT], then
press [
... ] or [ ... ]. No reaction when the frequency
~
is 000.0000. 1
IPress [MANUAL]. I*1 *2
-6-

1*1 1*2
Enter the desired frequency in each channel Enter search frequency as follows.
as follows. 1
Enter the desired frequency with numerical Press
[LiMIl] and enter the lower frequency of the
keys. range to search with numerical keys.
1
Press [ENTER] to memorize the frequency. If Press [ENTER].
wrong frequency (out of the band) is entered,
"Error" will be displayed. Press [CLEAR], and
then enter the correct frequency. Press
[LiMIl] and enter the upper frequency of the
1search range with numerical keys.
Press [PGM] to advance to the next channel.
Enter the frequency and press [ENTER]. Press [ENTER].
Repeat this to memorize all the frequencies.
1Press [A]to search from lower frequency. Press
[.] to
Press [PRI] so that priority channel appears. search from upper frequency (squelch must be on).
1
To revert to the previous channel, press [PRI] Press [AM/FM] to switch the mode to AM or FM.
again. 1To return to the default mode, press [AM/FM] while
To select a channel, enter a number (1 pressing and holding [CLEAR].
through 400), and then press [PRI]. 1
Priority channel will be changed to newly
entered channel. Press [MON] to store the desired frequency (10
1monitor channels) in the search mode.
To call monitor channels, press [MON].
To start search, press
[A] or [.].
1
Press [MON] so that the next monitor
channel appears. 1
To call the monitor channels directly, press
numerical keys. 1!
To revert to the previous channel, press
[PGM]. 1
Turn on [KEY LOCK] switch to unoperate all
keys except [SCAN], [MAN], and [LIG
Hl].
-7-

ALIGNMENT/ADJUSTMENT
Alignment and Test Point Locations
AF PCB ooRF PCB
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TCIOI
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TI02
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OTPI02
T103
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TPI03 L130
G> Jr(I.
ICIOI W~
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L129 r.......:8 XIOI !:o!
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ec; @ Wie: :.\~ @JTCI02
NO \ __ ~
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TP301
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LJL302
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Through hole where Pin15 of IC101
and C183 (10 pF) are connected.
Test equipment required:
Oscilloscope
AC SSVM
DC SSVM
8-ohm dummy load
AM/FM signal generator (30 to 1000 MHz)
Distortion meter
Frequency counter (1200 MHz)
Note:
Use non-metallic tuning tools.
The test equipment and the receiver should be warmed up tor at least 30 minutes betore proceeding to align-
ment.
The signallevel trom the generator should be kept as low as possible to obtain a usabie output.
Program CH1 to CH7 as follows:
Table 1
Channel Frequency(MHz) (FM/AM Mode)
130.0000 (FM)
2512.0000 (FM)
3999.9875 (FM)
4287.0000 (AM)
5510.4000 (FM)
631.9950 (FM)
732.0000 (FM)
-8-

Alignment Procedures
Alignment of veo (PLL 2)
Step Control Setting Test Instrument Connection Adjust Remarks
Channel Programming
OFFNOLUME
Control: Connect DC SSVM
to Adjust L130 to 2.4 volts on the DC
1
ON.
TP103 and GND as shown L130 SSVM, as shown in Table 3.
SQUELCH Control: Fully in Figure 1.
CCW (counterclockwise).
Select Channel 1.
Alignment of veo (PLL 1)
Step Control Setting Test Instrument Connection Adjust Remarks
Channel Programming
OFFNOLUME Control. Cannect DC SSVM to 1) Select Channel 2 and adjust
2ON. TP102 and GND as shown L129 L129 to 25.5 volts on the DC
SQUELCH Contral: CCW. in Fig. 2. SSVM, as shown in Table 2.
Select Channels 2 and 3. 2) Select Channel 3 and be sure
the DC SSVM shows 9.5-12
volts. (No adjustments are
necessary for the coil.)
Note: Repeat Step 1 and Step 2 until no further impravement is obtained. See Table 3.
Table 2
Figure 1
TP1 03 ~
~
DCSSVMUNIT
UNDER TEST
-Jr
Figure 2
TP102 o
UNIT DC SSVM
UNDER TEST
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Coil L129, L130 Coil Alignment (Open) Coil Alignment (Closed)
Figure 3 rUse Figure 4 Figure 5
-- non-metallic
Coil tuning tooi
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RF PCB •j
RF PCB RF PCB
Note:
.Be very
carerut when doing coil interval alignment be- Open the cail as shown Close the coil as shown
cause it greatly affects the frequency. above by using anon- above by using anon-
metallic tuning tooi when metallic tuning taal when
.Secure the coil with glue after alignment. Be sure the the measuring voltage at the measuring voltage at
glue is dry and the coil is secure. Also, be sure that TP102 or TP103 is higher TP102 or TP103 is lawer
the environmental temperature is normal. Then, re- than the setting voltage. than the setting voltage.
peat Step 1 and Step 2 above.
Table 3
CH Frequency Voltage
CH1 30 MHz Voltage at TP103: 2.3-2.5 volts
CH2 512 MHz Voltage at TP102: 2.5-2.6 volts
CH3 999.9875 MHz Voltage atTP102:
9.5-12 volts
-9-

Reference Frequency oseAlignment
Step Control Setting Test Instrument Connection Adjust Remarks
OFFNOLUME Control: Connect Frequency counter TC102 Adjust TC102 so that the fre-
ON. to TP101 and GND, as quency is 1123.200000±300 Hz.
3SQUELCH Control: Fully shown in Figure 3.
CCW.
Select Channel 2.
Figure 3
UNIT TP101 FREQUENCYCOUNTER
UNDERTEST
Jr
Note: If no frequency counters capable of measuring 1200 MHz are available, use a frequency counter capable
of measuring 20 MHz. Follow the instructions below and the frequency counter can do an approximate adjust-
ment.
1. The frequency counter for measurement should be accurate within 1 Hz.
2. Be sure a 2 pF capacitor is connected to the end of the cable of the signalline. The unit would be destroyed if
you did not use this capacitor.
If a capacitor other than the 2 pF capacitor is used, or if the capacitor is connected anywhere ether than the end
of the measurement cabie, correct measurement will never be obtained because of the effects on the oscillator.
3. Be sure the coaxial cabIe for measurement is as short as possible (shorter than 1 meter) to avoid stray capaci-
tance
eHects.
4. Test point locations and adjustment frequency range:
Pin15 of IC101 and C183 (10 pF) are connected to a through hole, as shown in "Alignment and Test Point Loca-
tions" (Page 8). Connect a 2 pF capacitor at the through hole pattern location and then adjust TC102 so that the
frequency range is 12.799937 MHz ±2 Hz.
Figure 4 2 pF
UNIT
0-
H: FREQUENCYCOUNTER
UNDERTEST
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-10-