WILLTEK 8100 Series User manual

8100 Series General Purpose Receiver
User’s Guide
boosting wireless efficiency
User’s guide
Version 4.00

WARRANTY
HARDWARE: Willtek warrants its hardware products to be free from defects in workmanship
and materials, under normal use and service, for one year from the date of purchase from Willtek
or its authorized agent. Willtek certifies that all instruments are tested and inspected to comply
with the published specifications originating from the company.
If a product does not operate as warranted during the warranty period, Willtek shall, at its option,
repair the defective product or part (except batteries), deliver an equivalent product or part to
replace the defective item, or refund the purchase price paid for the defective product.
Transportation of the defective product or part to the factory or service centre is to be pre-paid by
the customer. All products that are replaced will become the property of Willtek. Any replaced or
repaired product or part has a ninety (90) day warranty or the remainder of the initial warranty
period, whichever is longer.
SOFTWARE: Willtek warrants that the software programs licensed from it will perform in
substantial conformance to the program specifications for a period of one year from the date of
purchase from Willtek or its authorized agent. Willtek warrants the magnetic media containing
software against failure during the warranty period. Sole obligation hereunder shall be (at Willtek
discretion) to refund the purchase price paid for any defective software products, or to replace any
defective media with software which substantially conforms to applicable published
specifications. Willtek makes no warranty that its software products will work in combination
with any hardware or applications software products provided by third parties, that the operation
of the software products will be uninterrupted or error free, or that all defects in the software
products will be corrected. Willtek will make reasonable efforts to provide compatibility, except
where the non-compatibility is caused by a defect in the third party’s product.
All information in this manual is given in good faith. However, Willtek Communications shall not
be liable for any loss or damage whatsoever arising from the use of this manual, the product
described in it or any errors or omissions in either.
Willtek Communications
Gutenbergstr. 2 – 4
85737 Ismaning
Germany
Tel: [phone]
Fax: [phone]
Email: [email protected]
Web: www.willtek.com

Willtek 8100 Series General Purpose Receiver Contents
1
TABLE OF CONTENTS
ELECTROMAGNETIC COMPATIBILITY ........................................................................................7
CAUTION.................................................................................................................................................. 7
SECTION ONE −GENERAL INFORMATION .................................................................................. 9
1.1 SCOPE AND ORGANISATION OF THE MANUAL ............................................................ 9
1.2 PURPOSE OF EQUIPMENT AND GENERAL FEATURES................................................. 9
1.3 BASIC CONCEPT OF OPERATION ......................................................................................9
1.4 FRONT PANEL DETAILS .................................................................................................... 10
1.5 SIDE PANEL DETAILS......................................................................................................... 12
SECTION TWO −PREPARATION FOR USE..................................................................................13
2.1 INTRODUCTION................................................................................................................... 13
2.2 UNPACKING AND PHYSICAL INSPECTION................................................................... 13
2.3 INITIAL POWER-ON CHECKS............................................................................................ 13
2.4 FITTING ANTENNA ............................................................................................................. 13
2.5 BATTERY CHARGING AND CARE ................................................................................... 14
2.5.1 Introduction......................................................................................................................... 14
2.5.2 Battery Failure..................................................................................................................... 14
2.5.3 Battery Care ........................................................................................................................ 14
2.6 BATTERY REPLACEMENT................................................................................................. 15
SECTION THREE −SWITCHING ON............................................................................................... 17
3.1 PRELIMINARY ACTIONS ................................................................................................... 17
3.2 SWITCHING ON PROCEDURE...........................................................................................17
SECTION FOUR −BASIC DISPLAY AND CONTROL FUNCTIONS..........................................19
4.1 INTRODUCTION................................................................................................................... 19
4.2 DISPLAY FEATURES........................................................................................................... 19
4.2.1 Basic Display Features........................................................................................................ 19
4.2.2 SOFT Function Display Abbreviations............................................................................... 20
4.3 ROTARY CONTROLS........................................................................................................... 20
4.3.1 DISPLAY Control............................................................................................................... 20
4.3.2 LINE Control ...................................................................................................................... 21
4.3.3 SQUELCH Control............................................................................................................. 21
4.3.4 VOLUME Control .............................................................................................................. 22

Contents Willtek 8100 Series General Purpose Receiver
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4.3.5 TUNE/SELECT Control......................................................................................................22
4.4 PUSH-BUTTON CONTROLS................................................................................................22
4.4.1 CAL/LOCK Push-button.....................................................................................................23
4.4.2 SOFT/LIST Push-button......................................................................................................24
4.4.3 SCAN/PRTY Push-button...................................................................................................24
4.4.4 MEM/MODE Push-button...................................................................................................25
SECTION FIVE −DETAILED OPERATING INFORMATION......................................................27
5.1 INTRODUCTION ...................................................................................................................27
5.2 DETAILED CONCEPT OF OPERATION/METHODS.........................................................27
5.2.1 Normal and List Operation..................................................................................................28
5.2.2. Frequency and Memory Modes...........................................................................................28
5.2.3. Status List “Transfer” Function...........................................................................................28
5.2.4. Front Panel Controls............................................................................................................28
5.3 WARNINGS AND PROMPTS ...............................................................................................29
5.3.1. “ALL MEMORIES CLEAR”..............................................................................................29
5.3.2. “ALL MEMORIES DORMANT”.......................................................................................29
5.3.3. “AVERAGE.1s AND 1s ONLY FOR MODULATION MEASUREMENTS”..................29
5.3.4. “BATTERY FAIL” .............................................................................................................29
5.3.5. “BATTERY LOW”.............................................................................................................29
5.3.6. “BOTH PRIORITY CHANNELS DORMANT”................................................................29
5.3.7. “CANNOT STORE FREQUENCY WHEN IN MEMORY MODE”.................................29
5.3.8 “CAN ONLY USE LOCKOUT WHEN HOLDING” ........................................................29
5.3.9. “CHECK TYPE OF ANTENNA”.......................................................................................29
5.3.10. “LOCKED” .........................................................................................................................30
5.3.11. “LOCKOUT LIST CLEAR”...............................................................................................30
5.3.12. “LOCKOUT LIST FULL”..................................................................................................30
5.3.13. “MEMORIES FULL”..........................................................................................................30
5.3.14. “MICRO UNIT FAILURE”................................................................................................30
5.3.15 “MORE THAN ONE BUTTON PRESSED”......................................................................31
5.3.16 “NOT A SOFT FUNCTION”..............................................................................................31
5.3.17 “OUT OF LOCK” ...............................................................................................................31
5.3.18 “OVERLOAD”....................................................................................................................32
5.3.19 “OVER RANGE”................................................................................................................32
5.3.20 “PRESS FOR ONE SECOND TO COME OUT OF LIST”................................................32
5.3.21 “REDUCE RF INPUT LEVEL” .........................................................................................32
5.3.22 “REMOTE” .........................................................................................................................32
5.3.23 “ UNCAL”...........................................................................................................................32
5.3.24 “USE ONLY SOFT AND LIST”........................................................................................32

Willtek 8100 Series General Purpose Receiver Contents
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5.3.25 “USE ONLY SOFT LIST AND MODE”........................................................................... 32
5.3.26 “USE MEMORY LIST TO CHANGE VALUE”............................................................... 32
5.3.27 “VARIABLE AVE AND PEAK NOT SELECTABLE TOGETHER”.............................. 32
5.4 SET UP FACILITIES.............................................................................................................. 33
5.4.1 FUNCTION LIST Facilities ............................................................................................... 33
5.4.2 PRIORITY STATUS LIST Facilities ................................................................................. 41
5.4.3 LOCKOUT LIST Facilities................................................................................................. 41
5.4.4 MEMORY STATUS LIST Facilities.................................................................................. 41
5.4.5 MEMORY LIST Facilities.................................................................................................. 42
5.5 LEVEL (FIELD STRENGTH) MEASUREMENT ................................................................ 43
5.6 MOD (MODULATION/DEVIATION) MEASUREMENT................................................... 44
5.7 SIGNAL LEVEL DETECTION ............................................................................................. 45
5.7.1 Introduction......................................................................................................................... 45
5.7.2 AVERAGE 5 ms Detector.................................................................................................. 45
5.7.3 AVERAGE.1 s Detector ..................................................................................................... 45
5.7.4 AVERAGE 1 s Detector ..................................................................................................... 46
5.7.5 VARIABLE AVERAGE Facility ....................................................................................... 46
5.7.6 PEAK 1 s Detector.............................................................................................................. 46
5.8 AM/FM AUDIO DETECTORS.............................................................................................. 47
5.8.1 AM Detector ....................................................................................................................... 47
5.8.2 FM Detector........................................................................................................................ 47
5.9 SWITCHABLE AUDIO BANDPASS FILTER..................................................................... 47
5.9.1 Audio Filter OUT................................................................................................................47
5.9.2 Audio Filter IN.................................................................................................................... 48
5.10 IF BANDWIDTH SELECTION............................................................................................. 48
5.10.1 7.5 kHz Bandwidth .............................................................................................................48
5.10.2 15.0 kHz Bandwidth ........................................................................................................... 48
5.10.3 120 kHz Bandwidth ............................................................................................................ 48
5.11 CALIBRATION FACILITIES................................................................................................ 49
5.11.1 Introduction......................................................................................................................... 49
5.11.2 Calibration with AUTO CAL OFF ..................................................................................... 49
5.11.3 Calibration with AUTO CAL ON.......................................................................................49
5.12 SELECTABLE ATTENUATION........................................................................................... 49
5.12.1 Introduction......................................................................................................................... 49
5.12.2 Attenuation De-Selected (ATD) .........................................................................................50
5.12.3 Attenuation Fixed (ATF)..................................................................................................... 50
5.12.4 Attenuation Selected (ATS)................................................................................................ 50
5.13 SCANNING AND PRIORITY CHANNEL FACILITIES..................................................... 50
5.13.1 Introduction......................................................................................................................... 50

Contents Willtek 8100 Series General Purpose Receiver
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5.13.2 LIMIT SCAN Function .......................................................................................................51
5.13.3 MEMORY SCAN Function ................................................................................................51
5.13.4 PRIORITY CHANNELS Functions....................................................................................52
5.14 TYPICAL OPERATING FUNCTIONS..................................................................................52
5.14.1 Setting Up (FUNCTION and MEMORY LISTS)...............................................................52
5.14.2 Field Strength Measurement................................................................................................52
5.14.3 Modulation Measurement....................................................................................................53
5.14.4 Scanning ..............................................................................................................................54
5.14.5 Calibration...........................................................................................................................54
SECTION SIX −PROGRAMMABLE (RS-232-C) OPERATION....................................................55
6.1 INTRODUCTION ...................................................................................................................55
6.2 RS-232-C GENERAL INFORMATION.................................................................................55
6.3 SETTING UP THE RS-232-C INTERFACE..........................................................................56
6.3.1 Physical Connections...........................................................................................................56
6.3.2 Electrical Characteristics .....................................................................................................56
6.3.3 Data Format.........................................................................................................................56
6.4 COMMAND LANGUAGE.....................................................................................................57
6.4.1 Attenuation −AT.................................................................................................................58
6.4.2 Auto Calibration −AC.........................................................................................................58
6.4.3 Audio Detect −AD..............................................................................................................59
6.4.4 Audio Filter −AF ................................................................................................................59
6.4.5 Bandwidth −BW.................................................................................................................59
6.4.6 Baud Rate −BR...................................................................................................................60
6.4.7 Calibrate −CL .....................................................................................................................60
6.4.8 Channel Offset −CO...........................................................................................................61
6.4.9 Dwell Time −DT.................................................................................................................61
6.4.10 Frequency −FR...................................................................................................................61
6.4.11 Handshake −HS..................................................................................................................62
6.4.12 Level Detect −LD...............................................................................................................62
6.4.13 Level Units −LU.................................................................................................................62
6.4.14 Local Mode −LOC..............................................................................................................62
6.4.15 Lower Limit −LL................................................................................................................63
6.4.16 Memory Clear −MC............................................................................................................63
6.4.17 Memory Delete −MD..........................................................................................................63
6.4.18 Memory Recall −MR..........................................................................................................64
6.4.19 Memory Store −MS............................................................................................................64
6.4.20 Readout −RD......................................................................................................................64

Willtek 8100 Series General Purpose Receiver Contents
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6.4.21 Relative Value −RV........................................................................................................... 64
6.4.22 Remote Mode −REM ......................................................................................................... 65
6.4.23 Report Status −RS.............................................................................................................. 65
6.4.24 Scan −SC............................................................................................................................ 66
6.4.25 Signal Level −SG............................................................................................................... 67
6.4.26 Squelch Level −SQ ............................................................................................................ 67
6.4.27 Status −ST.......................................................................................................................... 67
6.4.28 Step Memory −SM............................................................................................................. 68
6.4.29 Tuning Steps −TS............................................................................................................... 69
6.4.30 Upper Limit −UL ............................................................................................................... 69
6.4.31 Variable Average −VA ...................................................................................................... 69
6.4.32 Variable Average Time −VT.............................................................................................. 70
6.4.33 Version Number −VN........................................................................................................ 70
6.5 ERRORS AND ERROR HANDLING.................................................................................... 70
6.5.1 Communication Errors........................................................................................................ 71
6.5.2 Errors Caused by Mistakes in the Argument ...................................................................... 72
6.5.3 Summary of Error Messages...............................................................................................72
6.6 ADVICE ON PROGRAMMING............................................................................................ 72
6.7 COMMAND SUMMARY ...................................................................................................... 74
SECTION SEVEN - TROUBLESHOOTING...................................................................................... 77
7.1 INTRODUCTION................................................................................................................... 77
7.2 received signal sounds noisy................................................................................................... 77
7.3 howling noise in loudspeaker.................................................................................................. 77
7.4 distortion on received signals..................................................................................................77
7.5 display corruption.................................................................................................................... 77
7.6 nothing on display ................................................................................................................... 78
7.7 no sound from the loudspeaker................................................................................................ 78
7.8 receiver does not respond to push buttons............................................................................... 78
7.9 signal level readout jitters........................................................................................................ 78
7.10 high residual reading on am or deviation bargraph................................................................. 78
7.11 deviation goes off scale when receiving a signal..................................................................... 78
7.12 receiver does not scan.............................................................................................................. 78
7.13 bargraph moves but level readout does not respond................................................................ 78
7.14 NO RS-232-C DATA.............................................................................................................. 79
SECTION EIGHT −SPECIFICATIONS AND ACCESSORIES...................................................... 81
8.1 INTRODUCTION................................................................................................................... 81
8.2 specification............................................................................................................................. 81

Contents Willtek 8100 Series General Purpose Receiver
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8.3 accessories AND OPTIONS....................................................................................................81
8.3.1 Standard Accessories...........................................................................................................81
8.3.2 Optional Accessories and Options.......................................................................................82
8.4 UPGRADE COMPATIBILITY...............................................................................................88
8.4.1 Firmware Upgrades .............................................................................................................88
8.4.2 Hardware Upgrades.............................................................................................................88
SECTION NINE −Willtek 8181 GPR DOWN CONVERTER OPERATING INSTRUCTIONS.89
9.1 GENERAL INFORMATION..................................................................................................89
9.2 OPERATION...........................................................................................................................89
9.3 SYSTEM SPECIFICATION −Willtek 8181 GPR Down Converter......................................90
PUBLICATION HISTORY....................................................................................................................91

Willtek 8100 Series General Purpose Receiver Electromagnetic Compatibility
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ELECTROMAGNETIC COMPATIBILITY
To comply with the Electromagnetic Compatibility Directive of the European Union the cables connected
to the Willtek 8100 Series General Purpose Receiver must be less than 2 metres in length. All cables with
the exception of the DC power lead must be screened.
To comply with the Electromagnetic Compatibility Directive of the European Union the 8100 must only
be operated from its internal battery and must not be charged whilst in use.
The external battery charger used with the 8100 must be CE marked as meeting the Low Voltage and
EMC Directives.
CAUTION
(1) Exercise care when removing the instrument from its shipping container to ensure that no damage
has occurred.
(2) It is inadvisable to leave the receiver exposed to strong direct sunlight or low temperatures for
long periods before making measurements. The receiver temperature may fall outside that given
in the specification (see Section 8) so causing the measurement accuracy and display response to
be impaired.
(3) Facilities are provided for giving a direct level readout of signal field strength, using the
VBA6106B for VHF, and the UPA6108 log periodic antenna for UHF. Many other antennas can
be used, but a correction factor has to be applied if a readout in dBµV/m is required.
(4) Care must be taken not to operate the receiver continuously at very high volume, to prevent
damage to the receiver circuits and loudspeaker.
(5) The internal NiCd battery is connected to pins on the Auxiliary 1 and Auxiliary 2 connectors.
A fire risk could result if these pins are shorted to the chassis of the receiver.

Electromagnetic Compatibility Willtek 8100 Series General Purpose Receiver
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Willtek 8100 Series General Purpose Receiver General Information
9
SECTION ONE −GENERAL INFORMATION
1.1 SCOPE AND ORGANISATION OF THE MANUAL
This manual provides a comprehensive operating guide to the Willtek 8100 Series portable
VHF and VHF/UHF measuring and monitoring receivers.
Sections 1 to 7 of the manual provide information generally applicable to all receivers in the
8100 range. Wherever possible, differences between specific types and models in the range are
detailed where they occur, but in some instances it is necessary to refer to Section 8 for specific
information.
Section 8 provides detailed specifications for all current 8100 models, at the date this manual
was printed. Please confirm which model you actually have, and refer to the appropriate table
for that model (Table 8-4).
Section 9 contains information about how to use the 8100 with the Willtek 8181 GPR Down
Converter (formerly GFC 4903).
The manual is organized to provide the user with operating information in the order in which it
is needed. Before turning on the equipment, it is recommended to read Sections 1 to 4 and the
“Detailed Concept of Operation/Methods” in Section 5.
Section 6 need only be read, if remote control of the equipment is to be used.
1.2 PURPOSE OF EQUIPMENT AND GENERAL FEATURES
The Willtek 8100 Series of measuring and monitoring receivers are tailored to specific needs,
their modular design allowing for easy upgrading. Section 5 provides an introduction to the
range of typical applications, plus examples of operating procedures common to these uses.
The receivers are true field instruments, both rugged and portable. They have a laboratory
accuracy and yet are easy to use. The comprehensive features have been incorporated without
the need for a large number of controls, and a single push-button enables more than
40 parameters to be set up and stored in non-volatile memory, backed up for ten years. The
LCD display, with an adjustable viewing angle, is ideal for outdoor use.
Using a “SOFT” push-button, critical parameters can be changed instantly, and field strength
can be either read directly or with a bargraph to indicate trends. Forty front panel settings,
including the squelch level, can be stored and recalled with edit facilities.
1.3 BASIC CONCEPT OF OPERATION
The receiver has two types of basic operation: NORMAL OPERATION and LIST
OPERATION.
(1) NORMAL OPERATION is used to carry out general measuring and monitoring
functions.
(2) LIST OPERATION is used to set up the required functions and parameters.
There are also two modes of operation: FREQUENCY MODE and MEMORY MODE.
(1) FREQUENCY MODE is used for the measuring and monitoring of signals, up to the full
frequency range of the receiver, and also “LIMIT SCANNING” between two previously

General Information Willtek 8100 Series General Purpose Receiver
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entered frequencies. Unwanted frequencies can be LOCKED OUT, and thereafter
bypassed during scanning.
(2) MEMORY MODE is used to measure and monitor specific frequencies, stored whilst in
FREQUENCY MODE. These frequencies can be scanned, and made “DORMANT” if
not currently required. Each memory channel stores, not only the frequency, but the
current receiver status at the time the frequency is memorized.
Refer to the “Detailed Concept of Operation/Methods” in Section 5, for a comprehensive
explanation of these operating methods.
1.4 FRONT PANEL DETAILS
With the exception of the ON/OFF control, the Front Panel provides all the operating controls
for the 8100 Series receivers. Figure 1-1 shows a view of the panel and details the main
functions of each control.

Willtek 8100 Series General Purpose Receiver General Information
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SQUELCH VOLUME
TUNE SELECT
Willtek 8100 GPR
CAL/LOCK
SOFT/LIST
SCAN/PRTY
MEM/MODE
LINE
DISPLAY
TUNES THROUGH THE RECEIVERS FREQUENCY RANGE
TUNES THROUGH THE MEMORIES
RESUMES MEMORY SCAN
RESUMES LIMIT SCAN
RESUMES PRIORITY CHANNEL
SCROLLS THROUGH MEMORY LIST
SCROLLS THROUGH FUNCTION LIST
LIQUID CRYSTAL
DISPLAY
ADJUSTS CONTRAST AND
VIEWING ANGLE OF DISPLAY
CALIBRATES / LOCK
CALIBRATE RECEIVER LOCKS CONTROLS
CHANGES THE SOFT FUNCTION
MAKES CHANGES ON FUNCTION LIST
MAKES CHANGES ON MEMORY LIST
SOFT/LIST DISPLAYS FUNCTION LIST
DISPLAYS MEMORY LIST
ADJUST LEVEL OF 600 OHM AUDIO
OUTPUT (SIDE PANEL) ADJUST THE SQUELCH THRESHOLD
ADJUSTS VOLUME
TO LOUDSPEAKER
AND EXTERNAL
SPEAKER SOCKET
(SIDE PANEL)
MEMORY / MODE
ENTERS THE RECEIVER STATUS
INTO A MEMORY CHANGES FROM FREQUENCY MODE
TO MEMORY MODE
SCAN / PRIORITY CHANNEL
STARTS AND STOPS SCANNING STARTS AND STOPS SAMPLING
OF PRIORITY CHANNEL
Figure 1-1. FRONT PANEL CONTROLS

General Information Willtek 8100 Series General Purpose Receiver
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1.5 SIDE PANEL DETAILS
This panel provides the ON/OFF switch, charger socket and indicator, and a reset switch plus
various external connectors. The external connectors are as follows:
(1) Headphones/Speaker. This socket provides a nominal output of 1 W to 3 Wrms into
8 Ω(dependent upon battery state).
(2) Line. This socket provides a low level audio output, variable using Front Panel
LINE rotary control but nominally 0 dBm (into 600 Ω).
(3) RS-232-C 9-pin ‘D’ Male
Pin No. Designation
2
3
4
5
7
8
RXD
TXD
DTR
GROUND
RTS
CTS
(4) Auxiliary 1 15-pin Compact ‘D’ Male
Pin No. Designation
1
2
3
4
5
6
7
8
11
12
13
Battery +Ve output (switched)
NC
+12 V External Power &
Battery Charge In
0 V
0 V
Remote On/Off +Ve In
Remote On/Off +Ve In
Remote On/Off +Ve In
Battery +Ve (Un-switched)
Battery +Ve (Un-switched)
Battery +Ve (Un-switched)
(5) Auxiliary 2 15-pin ‘D’ Female
Pin No. Designation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
0 V
Battery Power output (Switched)
Unfiltered Demodulation output
No Connection
No Connection
No Connection
SPEAKER OUT (8 Ω)
600 ΩLINE OUT (Nominal 0 dBm)
SIGNAL LEVEL OUT (1 V to 6 V)
Normally Open Squelch Relay 1
Normally Closed Squelch Relay 1
Common Squelch Relay 1
Normally Open Squelch Relay 2
Normally Closed Squelch Relay 2
Common Squelch Relay 2

Willtek 8100 Series General Purpose Receiver Preparation for Use
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SECTION TWO −PREPARATION FOR USE
2.1 INTRODUCTION
This section contains procedures for unpacking, inspection and initial power-on checks;
instructions for antenna fitment, plus battery charging and replacement, are also provided.
2.2 UNPACKING AND PHYSICAL INSPECTION
Examine the shipping carton for damage before unpacking the equipment. If the carton has been
damaged, have the carrier’s agent present when the equipment is removed from the carton.
Retain the shipping carton and padding material for the carrier’s inspection, if damage to the
equipment is evident after it has been unpacked.
CAUTION Exercise care when removing the instrument from its shipping container to
ensure that no damage is incurred.
See that the equipment is complete, as listed on the packing slip. Visually examine the
equipment for any evidence of physical damage. If any damage is evident, or if the contents are
not complete, immediately notify the carrier and also your local Willtek sales office. After
completing the physical inspection, the Initial Power-On Checks should be performed.
2.3 INITIAL POWER-ON CHECKS
Carry out the initial Power-on checks as follows:
(1) Ensure that no external equipment is connected via the RS-232-C interface.
The RS-232-C interface may be used after successful completion of these checks, and
instructions for use of this facility are contained in Section 6.
(2) Referring to Section 3, switch ON the equipment and check if the correct power-up
indications result.
Lack of power available may be due to discharged batteries.
It is now recommended to get to know all the equipment functions by reading the rest of this
handbook and carrying out typical operations. A check of each operational function should be
made as soon as possible after obtaining the equipment.
If problems are encountered, carry out the simple troubleshooting procedures detailed in Section
7. When a definite equipment failure is identified, write down full details of the problem and
contact your local Willtek sales office.
2.4 FITTING ANTENNA
There are many types of antennas available for use with the equipment and the one to be fitted
depends on the particular application.
Facilities are provided for giving a direct level readout of field signal strength, using the
VBA6106 biconical antenna in the VHF range and the UPA6108 log-periodic antenna in the
UHF range up to 1000 MHz.

Preparation for Use Willtek 8100 Series General Purpose Receiver
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2.5 BATTERY CHARGING AND CARE
2.5.1 Introduction
The receiver contains a pack of eight “D”-size nickel cadmium cells, giving at least eight hours
use. This life is considerably increased if the loudspeaker is operated at a low volume.
For the cells to be charged a 13.8 VDC source of suitable current rating is required (the normal
charging current for a receiver is 500 mA). The CBC 9710 battery charger is designed for this
purpose. The battery charger socket is located on the side panel (see illustration in Section 1).
Because the current limiting required for the nickel cadmium cells is carried out within the
receiver, other DC sources can be used (including the use of a 12 V vehicle battery).
The receiver can be left on charge indefinitely, without any harm to the cells. The receiver can
also be left on charge whilst it is in use (the batteries will be recharged, but at a reduced rate).
The receiver contains potentially hazardous Nickel Cadmium batteries, the safe disposal of
which must be carried out according to local government regulations.
2.5.2 Battery Failure
There is no simple rule about the life of nickel cadmium cells because there are so many factors
affecting their life, e.g. the number of charge/discharge cycles, the depth of discharges, the
temperature, etc.
There are three main failure modes:
(1) Gradual loss of capacity
(2) Short-circuit
(3) Inability to accept charge
After several hundred charge/discharge cycles, a reduction in the order of 20% of original
capacity will be experienced.
2.5.3 Battery Care
To prolong cell life it is good practice to occasionally run the batteries down so the battery
warning is left sounding for several minutes. If the receiver is not going to be used for a long
period of time, it should be stored with the cells in a fully charged condition.
It is inadvisable to leave the receiver on for a long time after the low battery warning operates,
as one or more of the cells may become reverse polarized. When this happens, it is common for
the cell not to accept any more charge.
When the cells are coming to the end of their charge/discharge life, it is possible for a sudden
short-circuit in one of the cells to occur. If it is suspected that one or more of the cells is
defective, or the capacity of the cells is below normal, the whole set of cells should be replaced.
In the interest of reliability, it is recommended that the cell pack be replaced every three years.

Willtek 8100 Series General Purpose Receiver Preparation for Use
15
2.6 BATTERY REPLACEMENT
To remove the set of battery cells, remove the receiver from its leather case and remove the
8 screws around the bottom of the receiver to release the battery cover.
WARNING DO NOT INCINERATE OR SHORT-CIRCUIT OLD CELLS
CAUTION Do not operate the receiver with the battery charger connected and the
batteries removed.

Preparation for Use Willtek 8100 Series General Purpose Receiver
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