POTOMAC INSTRUMENTS INC. PI 4100 User manual

PI 4100
Medium-Wave Field Strength Meter
User’s Guide

The following items are included with the original packing:
The PI 4100
PI 4100 User’s Guide
CD including PI 4100 Data Downloader software, 4100 Data Report
Template1software, and the PI4100 Field Calibration Data Sheet
Operator’s Quick Reference Guide
Charging power supply and power cord
Charging cable for vehicle use
USB A to B Cable
Battery holder for six AA cells
About the packing material:
Save the box and foam insert for use when returning the PI 4100 for calibration or
repair. See the User's Guide or www.pi-usa.com for return procedures.
Note that the foam inserts will fit exactly into the PELICAN® 1610 CASE for transport
and storage. This case is available from a number of suppliers that can be reached
via the internet.

PI 4100 Medium Wave Field Strength Meter
User’s Guide
Operating and Service Instructions
Version E, Universal
15 January 2014
Potomac Instruments inc,
7309 Grove Road, Unit D, Frederick, MD 21704, USA

Table of Contents
1. General Description .............................................................................................. 6
1.1 Overview .................................................................................................. 6
1.2 PI 4100 Key Feature ................................................................................ 7
1.3 Specifications ........................................................................................... 8
2. Receipt and Inspection .......................................................................................... 11
2.1 Unpacking ................................................................................................ 11
2.2 Reshipment to factory .............................................................................. 11
2.3 Service and Warranty for Equipment and Accessories ............................ 11
2.4 Factory contact information…………………………………………….. 11
3. Controls, Indicators, and External Ports ............................................................ 12
3.1 Front Panel ................................................................................................ 12
3.2 Primary Display Screen Elements ............................................................ 14
3.3 Rear Panel Signal and Power Ports ........................................................... 15
4. Operation ................................................................................................................ 16
4.1 First-Time Operation ................................................................................ 16
4.2 PI 4100 Operating Procedure Details ....................................................... 18
4.2.1 Setting the operating frequency ................................................ 18
4.2.1.1 Turn-on frequency ……............……………………. 18
4.2.1.2 MENU-Tx select ...………………………………… 18
4.2.1.3 FREQ PRESET ……………………………………. 18
4.2.1.4 FREQ SET ...……………………………………… 18
4.2.1.5 Harmonics …………………………………………. 18
4.2.2 Entering and changing station data for GPS use ....................... 18
4.2.2.1 Enter station data using MENU – Tx add..……….. 19
4.2.2.2 Enter station data using Data Downloader ………… 19
4.2.2.3 Change existing station data: MENU – Tx edit…… 19
4.2.3 Self-calibration, automatic and manual ..................................... 20
4.2.4 Saving Measurements: SAVE and HOLD ................................ 20
4.2.4.1 Starting a save …….……………………………….. 20
4.2.4.2 Completing the save ……………………………….. 21
4.2.4.3 Entering Save screen data before measuring ………. 21
4.2.4.4 The HOLD key …………………………………….. 21
4.2.4.5 View and delete saved data ………………………... 21
4.2.5 Measuring Field Strength .......................................................... 21
4.2.5.1 Field strength units ………………………………… 21
4.2.5.1 Loop antenna orientation …………………………... 21
4.2.5.3 LPF use…………………………………………….. 21
4.2.5.4 DC field strength output …………………………… 22
4.2.5.5 Temperature effects ………………………………... 22

4.2.5 Measuring Field Strength, cont’d
4.2.5.6 Measuring pure DRM transmissions ………………. 22
4.2.5.7 Measuring HD Radioall-digital transmissions…… 22
4.2.5.8 Low measuring limit ….……………………………. 22
4.2.5.9 High measuring limit ……………………………….. 22
4.2.5.10 Frequency range for measurements ……………….. 23
4.2.6 Measuring Harmonics ................................................................ 23
4.2.6.1 Measurement conditions ……………………………. 23
4.2.6.2 Measurement procedure …………………………….. 23
4.2.7 Spectrum mode operation .......................................................... 23
4.2.8 Measuring RF voltage: the RF In BNC jack ............................. 24
4.2.9 RF Out BNC jack use.................................................................. 24
4.3 Menu Operation Reference ........................................................................ 25
4.3.1 Menu Navigation………………………………………………. 25
4.3.2 Menu Item Description………………………………………… 25
4.4 Battery Information .................................................................................... 27
4.4.1 Charging the battery ................................................................... 27
4.4.2 Loose-cell battery ....................................................................... 27
4.5 Data storage and retrieval: The PI 4100 Data Downloader program .......... 28
4.5.1 General ......................................................................................... 28
4.5.2 Viewing and deleting data using the PI 4100 controls and
display.......................................................................................... 28
4.5.3 The PI 4100 Data Downloader Program...................................... 28
4.5.4 Data Downloader program installation ....................................... 28
4.5.5 Data Downloader program operation .......................................... 29
4.5.6 Data record fields ........................................................................ 30
5. Service Information ................................................................................................. 31
5.1 Maintenance ............................................................................................... 31
5.2 Troubleshooting and Repair ........................................................................ 31
5.3 Calibration .................................................................................................. 32
5.4 PI 4100 Calibration Verification Test ... ..................................................... 32
5.5 Contact Information .................................................................................... 35
6. Technical Information.............................................................................................. 36
6.1 Introduction ................................................................................................. 36
6.2 PI 4100 Technical Description..................................................................... 36
Appendix 1: Using the magnetic compass of the PI 4100 ............................................. 44
Appendix 2: PI 4100 Operation Quick Reference ......................................................... 46-47
Appendix 3: Sample ExcelField Strength Measurements Report ............................. 48
Appendix 4: PI 4100 Accessories................................................................................... 50

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1. General Description
1.1 Overview
The PI-4100 is Potomac Instruments’ third generation of precision survey instrumentation
designed specifically for the direct measurement of electromagnetic field strength in the 200 kHz to 5.1
MHz frequency spectrum. This microcontroller driven instrument combines a laboratory quality
measuring receiver, a balanced loop antenna, an internal GPS receiver, an internal calibration source, data
acquisition hardware and software, and a graphical LCD display in a single rugged package weighing less
than 3 kg. The device measures, displays, and at the option of the operator, records the following:
Field Strength. This instrument measures and indicates electromagnetic field strength in the 200 kHz to
5.1 MHz spectrum at levels ranging from 30 µV/m (29.5 dBuV/M) to above 50 V/m (154 dBuv/M).
Date & Time of measurement. For logging the PI 4100 indicates date and coordinated universal time
(UTC) derived from the Global Positioning Satellite (GPS) constellation. For users preferring to
record data in local time, the operator has the option of offsetting UTC time via menu selection.
Distance from the transmitting antenna or array. Line-of-sight distance from the point of
measurement to the transmitting source is displayed both for operator feedback and for logging. This
feature is enabled when the latitude and longitude coordinates of the source are entered into PI 4100
memory by the operator.
Magnetic bearing from the measuring point to the
transmitting antenna or array.
The PI 4100 indicates Magnetic Bearing (True Bearing ± Declination) to the sourceif the latitude and
longitude and magnetic declination for the source has been entered into memory.
True azimuth (radial) from the source to the measuring point. Conventional use of Field Strength
data often requires the data to be presented as a plot, on polar graph (or map), referenced to True
North. The PI 4100 employs its internal GPS receiver to calculate and display the True azimuth, in
degrees, from the sourceto the measuring point both for operator reference and logging purposes.
Geographical coordinates of the measuring point. The PI 4100 internal GPS captures and displays the
Latitude and Longitude of the physical location from which a given measurement is conducted
(degrees, minutes, and seconds). This information can be stored with other pertinent data for future
retrieval.
Spectrum occupancy (visual display) for the RF spectrum immediately adjacent to the measured
frequency. The spectrum display screen provides 1.0 kHz resolution bandwidth and a sweep width
of either ±22 kHz or ±64 kHz from center. Amplitude resolution on-screen is 1.0 dB. Carrier
frequency is displayed (center screen) and an internal Marker can be moved in increments of 1.0 kHz
either side of the carrier to precisely measure frequency response or interference level (in dB below
carrier with 0.1 dB resolution) at the Marker frequency.
Functional elements: The PI 4100 Functional Block Diagram, Fig. 1, p. 10, shows the PI 4100's
functional elements.

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1.2 PI 4100 KEY FEATURES
● 126 dB dynamic range measuring receiver
● Digitally synthesized tuning in 1.0 kHz increments
● Spectrum display to facilitate various measurements (Field Strength and Spectrum occupancy) in a
single instrument
● Provisions for a third party calibration check, using their laboratory standards, when it is impractical
to return the instrument to the manufacturer for calibration
● Data acquisition software and PC interface to enable the collection, analysis, and e-distribution of
field measurements. (This feature anticipates the future acceptance of data e-filing by federal
regulatory agencies.)
● Magnetic compass to aid in the initial orientation of the integral loop antenna
● External RF input port (BNC) so that the instrument can be used as a stand-alone calibrated tuned RF
Voltmeter
● External RF output port (BNC) so that the buffered output from the loop antenna can be used to drive
external detectors and spectrum display devices
● USB port for downloading data from the PI 4100 internal memory to a compatible computer
● Comma separated data format for ease of importation to third party commercial software
● DC Field strength output for external recording
● DRM and HD Radiomeasurement capability with automatic correction

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1.3 SPECIFICATIONS
Field Strength Measurement
Frequency Range 520 kHz to 5.1 MHz or 200 kHz to 5.1 MHz, calibrated
Minimum frequency step 1.0 kHz
Measuring accuracy:
AM & Simulcast DRM ± 3 %
Pure DRM ± 6 %
Field strength measuring range:
AM & Simulcast DRM 28 dBuV/m to 154 dBuV/m (25 μV/m to 50 V/m)
Pure DRM, 4.5/5 kHz BW 33 dBuV/m to 146 dBuV/m
Pure DRM, 9.0/10 kHz BW 36 dBuV/m to 146 dBuV/m
Pure DRM, 19/20 kHz BW 39 dBuV/m to 146 dBuV/m
Measurement units μV/m-mV/m-V/m; mV/m only;
dBuV/m (dB above 1 µV/m)
Measurement bandwidth 1.0 kHz @-3 dB
Image rejection ratio 60 dB
Spurious rejection 75 dB
Harmonic measurement
Harmonics, menu-selected 2nd, 3rd, 4th, 5th
Measurement range to -80 dBc or lower, for carrier FS of (0.3 – 3) V/m
Spectrum Display
Modes Norm (referenced to center freq FS)
Peak (Norm with peak hold)
Abs (displays 20 - 140 dBuV/m FS)
Center frequency range Same as FS frequency range
Span (Sweep width) 128 kHz, 45 kHz
Resolution bandwidth 1 kHz
I/O Ports:
Data output jack USB B jack
Cal In jack BNC, nominal calibration input 700 mV rms
RF In jack BNC, RF input and dc FS output
RF Out jack BNC, RF output and dc cal detector output
Headphone jack Audio jack, 3.5 mm
Battery charging jack Power jack, 2.1 mm

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RF Voltmeter (RF In jack)
Input impedance 2500 Ω
Voltage range 30 μV to 40 V rms
Measurement units μV-mV-V; mV only; dBuV
RF Out 28 ±2 mV rms in 50Ω for 1 V/m FS, 200 kHz – 5.1 MHz
DC Field Strength output Proportional to dBuV/m, 1.0 Vdc @ 100 dBuV/m with a
1 MΩ load (10 mV/dB)
Audio outputs For AM and Simulcast DRM only:
Front panel speaker
Headphone jack, 3.5 mm, mono or stereo
(use disconnects speaker), up to 4.0 V p-p max output
Data items stored 28 items, listed in Users Guide Sec. 4.5.6
Battery power supply
Battery type Rechargeable NiMH, 7.2 V, PI supplied
Battery operating time 5 hours min., new battery
Battery recharge time 3 hours typical for full charge
Charging supply 11 - 15 Vdc, 1.2 Amperes min., 2.1 mm plug
Alternative battery Six AA cells in a PI-supplied battery holder
Environmental characteristics:
Operating temperature range 0ºC to 50ºC dry, RH 95% (non-condensing)
Operating altitude Up to 13000 ft. (4700 m)
Dimensions and weight:
Length, Width, Height L: 15 in, 38 cm W: 7 in, 18 cm H: 11 in, 28 cm
Weight 5.5 lb, 2.5 kg

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Figure 1. PI 4100 Functional Block Diagram

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2. Receipt, Inspection, and Reshipment
2.1 Unpacking
The PI 4100 is packed in a custom shipping carton. Inspect the carton for any signs of serious
damage. Report any damage to the shipping company.
Carefully remove the PI 4100 from the shipping carton. A User’s Guide, a charger power supply
with power cord, an in-vehicle charging cable, a battery holder, a USB cable, and a CDROM are included
in the carton. Please retain the carton, the plastic foam insert holding the PI 4100, and other packing
materials in case the unit and accessories must be shipped. The foam insert can be used in the Pelican
1610 hard case, see Appendix 4 for details.
The PI 4100 is ready for operation as delivered. See Section 4 of this Manual for operating
instructions. WARNING
In all locations where power receptacles have a ground pin socket, the PI 4100 recharging
power supply’s power input ground terminal must be connected to the receptacle ground pin
socket. Failure to use a grounded outlet may result in improper operation or a safety hazard.
2.2 Reshipment to factory
If a PI 4100 must be returned to the factory it is best shipped in its original carton and packing
materials or in a Pelican 1610 case. Shipping cartons can be ordered from the factory if suitable
packaging is not available. Contact information can be found below and in Section 5 of this Guide.
2.3 Service and Warranty for Equipment and Accessories
Warranty: Potomac Instruments, Inc., warrants each new equipment to be free of defects in
material and workmanship, for a period of one (1) year after the date of receipt of the equipment in
satisfactory working condition. Any instrument which is found within one year not to meet the foregoing
standards after examination by our factory or representative, will be repaired, or at the option of Potomac
Instruments, replaced without charge. This warranty does not apply to equipment which has been altered,
improperly handled, or damaged after receipt.
If the PI 4100 fails to perform properly, initially or after a period of use, or if it requires factory
recalibration: if there is a local factory-authorized dealer or service facility, first contact the dealer or
facility. A technician there will determine the best procedure to deal with the problem, in consultation
with the factory if necessary. Otherwise, contact the factory directly. In either case it is recommended to
use the use the factory online RMA (Returned Material Authorization) system by going to the Potomac
web site at http://www.pi-usa.com, and clicking Request Service - On-line RMA Request. For units
that are not under warranty, repair cost estimates will be provided, and authorization to proceed will be
obtained from the customer before repairs are carried out. If return to the factory is not possible, Potomac
Instruments will work with the authorized service facility or user to complete the repair, and will supply
technical data and parts as necessary.
2.4 Contact information
Factory:
Potomac Instruments inc.
Attn: Service Dept.
7309 Grove Road, Unit D
Frederick, MD (Maryland) 21704
Phone: [phone]
Fax: [phone]
email: [e-mail]
http://www.pi-usa.com

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3. Controls, Indicators, and External Ports
3.1 Front Panel
Refer to Figure 1 or to the PI4100 itself for the following discussion. Each control is described
below, starting with the Power/Bklt key, and moving counterclockwise aound the panel to the other
keys..
Figure 1. PI 4100 Front Panel Controls and Indicators
POWER/BKLT:Turns the 4100 on (press until screen text appears) and off (press until screen text
disappears). Turns the display backlight on and off, a short press for both.
UP and DOWN arrowhead keys: These keys (1) move a reverse video cursor to step through the
choices available in the menu and submenus, and (2) step through the available values of a digit or
character, 0-9 and/or A-Z.
LEFT and RIGHT arrowhead keys: These keys (1) for some menu items, move an underline cursor to
select options; (2) for some menu items, move a reverse video cursor to select a number or character to
change; and (3) for FREQ SET, move an underline cursor to select digits to change.
MENU:When in the field strength screen or a spectrum screen, press to display the menu of operational
and setup options; press again to go back to the previous screen. For details see Sec. 4.3, p. 24.
SELECT:Used in menu operations to confirm a selection from a list, to confirm the choice of an item to
modify, and to confirm that the modification is complete, all in accordance with on-screen instructions.
DELETE:Used to review the data records stored in the PI 4100, and (using SELECT)to delete selected
data records. For details see Sec. 4.5.2, p. 27.
AUDIO/F4:Turns audio in the speaker or headphones on and off, a short press for on and a long press
for off. For audio on, short presses step the sound level through four steps. For F4 see FREQ PRESET.

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SAVE/F3:Used to save a measurement and associated data in internal memory. Press once to review
and change the associated data on the Save screen, and press again to complete the Save operation and go
back to the Field Strength screen. For details see Sec. 4.2.4, p. 19. For F3 see FREQ PRESET.
HOLD/F2:When pressed, the field strength value at that time is held on the display and in temporary
memory. For details see Sec. 4.2.4, p. 19. For F2 see FREQ PRESET.
LPF/F1:Controls stepping through three low-pass filter choices for three degrees of field strength value
smoothing. For details see Sec. 4.2.5.3, p.20. For F1 see FREQ PRESET.
FREQ PRESET:Allows quick selection of any of four previously stored frequencies which are shown
on the display as F1, F2, F3, and F4 after FREQ PRESET is pressed. Selection is made by pressing
one of the keys marked F1, F2, F3, or F4 as indicated above. For details see Sec. 4.2.1.3, p. 17.
FREQ SET:Allows setting the receive frequency to any available value by setting each digit of the kHz
number on the display to the desired value. For details see Sec. 4.2.1.3, p. 17.
MODE:From the Field Strength screen, steps the display through three spectrum display modes and
back to the Field Strength screen. For details see Sec. 4.2.7, p.22.
BATT LED:Signals by flashing that the 4100 will soon turn itself off because of low battery voltage and.
the battery pack needs to be recharged. For details see Sec. 4.4.1, p. 26.

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3.2 Primary Display Screen Elements
Refer to Figure 2 or to the PI4100 itself for the following discussion. Screen element descriptions are
given below with reference to horizontal lines of text, starting at the top with Line 1 and reading from
left to right in each line. For more detail on an item refer to Sec. 4, Operation.
Figure 2. PI 4100 Field Strength display
Line 1: Call sign of the selected station; Time and date from GPS (UTC + Offset).
Line 2: Frequency of the selected station; Modulation type; Battery voltage.
Line 3: Field strength value and units; Field strength trend indicator, points up for increasing, down
for decreasing field strength.
Line 4: Field strength value and units; LPF setting, degree of field strength smoothing, 1, 2, or 3;
internal temperature, ºC..
Line 5: Analog field strength indicator, each major division indicates 1 dB (12%) change.
Line 6: Bearing (magnetic) of the station from the PI4100; Azimuth of the PI4100 from the station.
Line 7: Distance of the PI4100 from the station; Internal correction value (for reference only)
Line 8: Latitude of the PI4100, degrees/minutes/seconds, from GPS.
Line 9: Longitude of the PI4100, degrees/minutes/seconds, from GPS; Number of GPS satellites in
view.
Lines 10, 11,12: Prompts for the operator, on manual self-calibration, storing a reading, and menu use.
Prompts vary with screen function.

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3.3 Rear Panel Signal and Power Ports
RF calibration input Headphone jack
RF voltmeter input Battery charging jack
DC field strength output
Buffered antenna RF output USB data port
Cal detector dc output
Figure 4. Charger Cable installed for charging Figure 5. Battery charger and Interface
Cables supplied
Figure 3. PI 4100 Rear Panel Signal and Power Ports

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4. Operation
4.1 FIRST- TIME OPERATION
After unpacking the 4100, a trial run will help a new user to become familiar with its operation.
The following is suggested:
Connect and charge the supplied battery pack, if either is necessary.
Adjust the compass index
Go outdoors and try some field strength measurements.
Review the menu options and enter the time offset between UTC and local time.
Enter data for a station to be measured.
Use GPS-derived data and the compass to orient the 4100.
Make and save some field strength measurements.
Download the measurement results to a computer.
Details on operating the 4100 can be found throughout this Guide, therefore browsing through the
Manual may reveal information of special interest.
Connect the battery:
The 4100 is shipped with its battery pack connected except in unusual circumstances. If it is
shipped with the pack disconnected (there is no response on pressing the POWER key), connect the
battery as follows:
Open the battery access door at the bottom of the front panel by pulling the upper left-hand
corner of the door away from the panel.
Locate the cable on the battery as well as the cable to the unit above. Both cable ends are
usually found under the battery, after the battery is removed.
Plug the connectors on these two cables together and reinstall the battery with the mated
connectors under the battery.
Close the battery door, pressing in on first the sides and then the top of the door so the flange on
the inside of the door is caught behind the panel edges.
Adjust the compass index:
The 4100's compass has a red vertical index line facing the operator, which should be on center,
aligned with the joint line of the two halves of the compass mount. If it is not so aligned, rotate the
compass in its mount to bring the index line into alignment.
Adjust the hand strap:
To adjust the length of the strap, separate the two halves of the wide padded part of the strap,
which are held together by hook-and-loop material. Pull the lower strap end loose from the pad,
reposition it in the bottom metal loop as desired, press the strap back onto the pad it was removed from,
and press the two padded halves together. The strap can be moved to the right-hand side of the 4100 by
removing and reinstalling the screws that fasten the strap mounting rings to the case.
Turn on the 4100 and make a measurement:
Turn the 4100 on: Press POWER/BKLT until text appears on the display. If the battery has
enough charge the main screen appears after a few seconds. If nothing appears on the display the pack
must be charged, see Battery information, Sec. 4.2.5.. When text appears look for the battery voltage
readout BATT 7.2V (7.2V is a typical value) at the right side of the screen near the top. If the voltage is
7.0 or more, go ahead with measurements. Sec. 3.2, p. 14, describes other screen elements.

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Set the frequency: Change from the factory set 500 kHz to the frequency of the desired station.
A stronger one is better for the first try: Press FREQ SET; a cursor line appears under the 10 kHz digit
(for 9 kHz channel spacing, the 1 kHz digit). Set that digit to the desired value using the up & down
arrow keys (UD). Use the left arrow key to move the underline to the next digit to be changed, and
change it in the same way. Repeat until the display shows the desired frequency.
Press AUDIO to hear the station's audio: The level does not change with field strength. Short
presses of AUDIO will change the sound level through four steps and a long press turns it off. Audio
quality is limited by the receiver's narrow bandwidth and the speaker's small size.
Start Self-Calibration: Press and hold the LPF/F1 key until CAL appears in a box. Self
calibration at the selected frequency proceeds and ends with CAL OK in a box if all is normal.
Measure Field Strength: orient the loop antenna for maximum reading (while keeping it
vertical) by using the analog indicator, a small block which moves right or left as the level increases or
decreases. There is also a trend indicator with an arrow that points up when level is increasing and down
when it is decreasing. To reduce rapid variations in the reading, usually due to modulation, press LPF; on
the display LPF1 changes to LPF2. This reduces variation and slows response time by applying a
lowpass filter. Press LPF again to obtain more filtering; LPF2 changes to LPF3. A third press of LPF
returns to LPF1 for the least filtering.
When the reading is maximum press SAVE to save the reading. The value is held internally
while the screen changes to the Save Screen, in which additional data can be entered and saved with the
measurement. On this screen the operator has the option to enter the pattern being measured, a
letter/number code for the measurement location, operator's ID, and a 14-character note. After the desired
entries are made, press SAVE again to complete the operation and return to the field strength screen.
GPS use: In an outdoor location where GPS reception is possible, latitude and longitude will
appear on the display (the first fix after the 4100 has been shipped a long distance may take several
minutes). Distance, azimuth, and bearing can be displayed if the latitude, longitude, and magnetic
variation are entered in the 4100 for the transmitting antenna location. To do this, press MENU, go to Tx
add, and enter the data. For more detail see Sec. 4.2.2, p.18. The 4100 can now be oriented for
measurements by making the compass reading equal to the bearing value on the display.
Downloading data to a computer: To download data, first, install the 4100 Data Downloader
program supplied with the 4100 and start the program (see Sec. 4.5, p.28). A program window appears
with four buttons indicating the tasks the program can perform. When a USB cable, Type A to Type B, is
connected between the computer and the 4100, “PI 4100 connected” appears at the top of the program
window and the 4100 display blanks. On the computer click the top “Download...” button; specify the
file name of the .csv file that will contain the data and where that file is to be stored. The download then
proceeds. Downloaded data may be viewed in the program or by opening the .csv file in a spreadsheet
program.
To turn the 4100 off, press and hold down POWER/BKLT until the screen text disappears after
about two seconds.

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4.2 PI4100 Operating procedure details
4.2.1 Setting the operating frequency:
Frequency can be set in these ways:
Accept the turn-on setting
MENU - Tx select
FREQ PRESET key
FREQ SET key
MENU - Harmonic select
4.2.1.1 Turn-on: A new 4100 turned on for the first time shows the factory setting, 500 kHz. If
the unit has been used: if it was on a frequency chosen using Tx select (see below) at turn-off, it will be
on that frequency when next turned on. If it was on a frequency set using FREQ SET at turn-off, when
turned on it will be on the frequency most recently selected using Tx select, or on 500 kHz.
4.2.1.2 Use MENU-Tx select to make a radio station for which data has been stored the active
station. The station's frequency and call sign appear on the display, and its antenna location and
declination is used to calculate distance, azimuth, and bearing. For DRM and all-digital HD stations a
correction is added to the field strength reading. A new unit will have no station data stored.
To use Tx select: Press MENU; with the cursor on Tx select press SELECT; use the up-down
keys to select a station: press SELECT; press MENU. If the desired station is not shown, use Tx add in
the menu to enter it, see Sec.4.2.2. Self-calibration will take place automatically.
4.2.1.3 Use FREQ PRESET to change to a new frequency. To store a frequency as a preset to
use later, first use MENU-Tx select to go to that frequency (only frequencies stored in Tx select can be
made presets). Then press FREQ PRESET; press one of the F1 -F4 keys and hold it down until you
hear a beep and the display shows the new frequency. Repeat this for other frequencies desired as presets.
To go to a preset frequency, press FREQ PRESET; the display shows the available presets.
Briefly press the F1 … F4 key for the desired frequency, do not hold the key down. If station location
data has been entered for that frequency, and GPS reception is possible, location-related data, date, and
time appear on the display. Self-calibration will take place automatically.
4.2.1.4 Use FREQ SET to change to a new frequency. To set a frequency:Press FREQ SET;
use up-down keys to change the frequency digit over the underline cursor; press the left key to move the
cursor to the next digit, changing its value the same way; repeat as needed. The 4100 will then receive a
signal on the new frequency but no location-related or time data will appear. For accurate measurements
press LPF to initiate self-calibration, holding the key down until CAL appears in a box.
4.2.1.5 Use MENU-Harmonic to go to a harmonic of the current frequency. To select a
harmonic, press MENU and use the down arrow to go to Harmonic: 1 2 3 4 5. Use the right arrow key
to move the underline cursor to, for example, 3 for the third harmonic, and press MENU. The receive
frequency then changes to three times the displayed frequency, and on the display, 3x appears to the left
of the frequency. If a new frequency is selected by using Tx select or FREQ PRESET, the harmonic
selection changes to the fundamental. For more detail see Sec. 4.2.6, p.23, Measuring Harmonics.
4.2.2 Entering and changing station data for GPS use
To use the internal GPS receiver to obtain distance and azimuth of the measuring point from the
transmitting antenna, and to use the compass for loop antenna aiming, data must be stored in the 4100 for
the station to be measured. Data is stored, modified, and retrieved by using the menu items Tx add, Tx
edit, and Tx select. As many as 50 stations may be entered. Station data can be entered by using the
front-panel keys or by using the Data Downloader program, see Sec. 4.5.4, p. 28. If the GPS derived data
is not needed, measurements can be made without this data-entry step by using FREQ SET to set the
frequency.

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4.2.2.1 To enter station data using MENU – Tx add:
Press POWER/BKLT to turn on the 4100.
Press MENU after the field strength screen appears; the menu screen appears.
Press the Down arrow key to go to Tx add; press SELECT. The Tx data entry screen appears,
listing six data items to be entered, and with the reverse video cursor on the first item, Call -Site.Call is
the station identifier; if there is more than one antenna site for the call, each one can have a separate Tx
entry with the same call but a different dash number. As many as eight characters can be entered. Press
SELECT; reverse video appears on the first character. Press the Up key to scroll through the numbers
and the alphabet, or press the Down key to scroll backwards, to change this character to the desired one.
Press the Right arrow key to go to the next character and change it the same way. Continue this
procedure until all characters are as desired, then press SELECT to exit Call-Site.
Press Down to go to Freq, and press SELECT. Proceed as for Call-Site, using the arrow keys
to change each frequency digit to the desired value. When done press SELECT, as before, to exit Freq..
At this point it is possible to exit Tx add, if the location data is not available or not of interest,
and the new entry will appear in the Tx select list.
To enter location data, move to each of the remaining data items and enter the required data.
Latitude and Longitude are the transmitting antenna location coordinates in degrees, minutes,
and seconds.
Var is the magnetic declination, also known as variation, the angular difference in degrees and
minutes between the bearing of true north and magnetic north. It can be calculated from the latitude and
longitude at this NOAA web site: http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp.
Modulation is the modulation system used by the station. Going to Modulation and pressing
SELECT gives the available choices. AM refers to normal double-sideband amplitude modulation. DRM
with a number refers to Digital Radio Mondiale; the number is the occupied bandwidth in kHz. HD-ad
refers to the all-digital mode of HD Radio. When a DRM or HD station is selected in the 4100, a
correction is automatically added to the field strength reading to account for the difference between the
measuring bandwidth, 1.0 kHz, and the occupied bandwidth. The DRM correction would be valid for any
digital modulation system of the same bandwidth in which the power per unit bandwidth is uniform
across the band.
When the required data has been entered, press MENU to go back to the main menu, and
press MENU again to return to the field strength screen. The station just entered becomes the active
station, meaning that the receiver is tuned to its frequency. Its antenna coordinates are used to calculate
distance, the azimuth of the 4100 from the station, and the magnetic bearing of the station from the 4100.
4.2.2.2 To enter station data using the Data Downloader Program: With this program, data
can be entered from the keyboard of a connected computer. To do this see the Downloader program
instructions, Sec. 4.5.4, p. 28.
4.2.2.3 To change existing station data: MENU – Tx edit: Press MENU, go to Tx select, and
select the station needing a change. Press SELECT to return to the menu, go to Tx edit, and press
SELECT again. All data items for the selected station can then be entered or edited as described above
for TX add.