Related ARRL Publications and Products:
The 1998 ARRL Handbook for Radio Amateurs has a chapter on test equipment and measurements. The book is available for $32.00 plus $6 shipping and handling. The Handbook is also now available in a convenient, easy to use CD-ROM format. In addition to the complete Handbook text and graphics, the CD-ROM includes a search engine, audio clips, zooming controls, bookmarks and clipboard support. The cost is $49.95 plus $4.00 shipping and handling. You can order both versions of the Handbook from our web page at http://www.arrl.org, or contact the ARRL Publications Sales Department at 888-277-289 (toll free). It is also widely stocked by radio and electronic dealers and a few large bookstores. The ARRL Technical Information Service has prepared an information package that discusses Product Review testing and the features of various types of equipment. Request the "What is the Best Rig To Buy" package from the ARRL Technical Department Secretary. The cost is $2.00 for ARRL Members, $4.00 for non-Members, postpaid. Many QST "Product Reviews" have been reprinted in three ARRL publications: The ARRL Radio Buyers Sourcebook (order #3452) covers selected Product Reviews from 1970 to 1990. The cost is $15.00 plus $4.00 shipping and handling. The ARRL Radio Buyers Sourcebook Volume II (order #4211) contains reprints of all of the Product Reviews from 1991 and 1992. The cost is $15.00 plus $4.00 shipping and handling. The VHF/UHF Radio Buyers Sourcebook (order #6184) contains nearly 100 reviews of transceivers, antennas, amplifiers and accessories for VHF and above. You can order these books from our Web page or contact the ARRL Publications Sales Department to order a copy. ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 3
QST is also available on CD ROM! The 1997 ARRL Periodicals CD ROM (order #6729), the 1996 ARRL Periodicals CD ROM (order #6109) and the 1995 ARRL Periodicals CD ROM (order #5579) each contain a complete copy of all articles from a years worth of QST, the National Contest Journal and QEX (ARRL's experimenter's magazine). Each CD is available for $19.95 plus $4.00 for shipping and handling. Contact the ARRL Publications Sales Department to order a copy. Older issues of QST are also available: QST View CD-ROMs come in sets covering either five years each (1990-1994, 19851989, 1980-1984, 1975-1979, 1970-1974, 1965-1969 and 1960-1964) or ten years each (1950-1959, 1940-1949 and 193039). The price for each set is $39.95. Shipping and handling for all ARRL CD ROM products is $4.00 for the first one ordered, $1.00 for each additional set ordered at the same time.

AC ONLY

TWO-TONE AUDIO GENERATOR

PTT SWITCH TELEGRAPH KEY

CAUTION!: Power must only be applied to the attenuator input! Do not reverse input and output terminals of the Bird 8329. RF Power Attenuator & Dummy Load Bird 8329

DUT TRANSMITTER

100 WATTS TYPICAL
RF WATTMETER BIRD WATTS TYPICAL

POWER SUPPLY

DC ONLY
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 5
Transmitter Output Power Test Results:
Frequency Band 1.8 MHz 3.5 MHz 3.5 MHz 7.0 MHz 10.1 MHz 14 MHz 14 MHz 14 MHz 14 MHz 14 MHz 18 MHz 21 MHz 24 MHz 28 MHz 28 MHz 50 MHz 50 MHz 50 MHz 50 MHz 144 MHz 144 MHz 144 MHz 144 MHz Mode Unit Minimum Power (W) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Measured Minimum Power (W) 1.6 W 1.7 1.5 1.8 1.8 1.8 1.8 N/A N/A N/A 1.8 1.8 1.8 1.8 1.5 1.8 Unit Maximum Power (W) 100 50 Measured Maximum Power (W) 97.4 W 110.0 32.4 W carrier 107.3 107.0 106.2 110.2 N/A N/A N/A 106.7 107.4 107.2 108.6 100.8 108.8 100.5 27.9 W carrier 107.0 50.4 49.0 16.5 W carrier 47.9 Notes
CW CW AM CW CW CW USB CW CW CW CW CW CW CW FM CW FM AM SSB CW FM AM SSB

10, 99 11, 99 12, 99

Notes: 1. Unit's power meter consists of LED segments; minimum power showed 0 segments lit. 2. The unit showed LED segments reaching a fixed display label reading 100 at full power. 10. Temperature chamber test at -10 degrees Celsius. 11. Temperature chamber test at +60 degrees Celsius. 12. Output power test at 11.5 volts dc power supply (if applicable). 99. Temperature chamber tests and 11.5 volt tests are performed only for portable and mobile equipment.
Transverter Jack Output Power Test:
Test Description: This test measures the output power from the transverter jack (if applicable). This is usually somewhere near 0 dBm. The transverter-jack power usually varies from band to band. The 28-MHz band is the most common band for transverter operation. Most transverter outputs are between -10 dBm and +10 dBm. Test Results: Frequency 20 M 15 M 10 M

Output

Notes 1
Notes: 1. Unit does not have a transverter jack.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 6
Current Consumption Test: (DC-powered units only)
Test Description: Current consumption can be a important to the success of mobile and portable operation. While it is most important for QRP rigs, the ARRL Lab tests the current consumption of all equipment that can be operated from a battery or 12-14 vdc source. The equipment is tested in transmit at maximum output power. On receive, it is tested at maximum volume, with no input signal, using the receiver's broadband noise. Any display lights are turned on to maximum brightness, if applicable. This test is not performed on equipment that can be powered only from the ac mains. Current Consumption: Voltage Transmit Output Power Current 13.8 V 20 A 100.2 W

Receive Current 2.5 A

Lights? ON
Transmit Frequency Range Test:
Test Description: Many transmitters can transmit outside the amateur bands, either intentionally, to accommodate MARS operation, for example, or unintentionally as the result of the design and internal software. The ARRL Lab tests the transmit frequency range inside the screen room. The purpose of the Transmit Frequency Range Test is to determine the range of frequencies, including those outside amateur bands, for which the transmitter may be used. The key test conditions are to test it at rated power, using nominal supply voltages. Frequencies are as indicated on the transmitter frequency indicator or display. Most modern synthesized transmitters are capable of operation outside the ham bands. However, spectral purity is not always legal outside the hams bands, so caution must be used. In addition, most other radio services require that transmitting equipment be type accepted for that service. Amateur equipment is not legal for use on other than amateur and MARS frequencies. Test Results: Frequency 160 M 80 M 40 M 30 M 20 M 17 M 15 M 12 M 10 M 6M 2M
Low-Frequency Limit 1.800.00 MHz 3.400.00 MHz 6.900.00 MHz 9.900.00 MHz 13.900.00 MHz 17.900.00 MHz 20.900.00 MHz 24.400.00 MHz 28.000.00 MHz 50.000.00 MHz 144.000.00 MHz
High-Frequency Limit 1.999.99 MHz 4.099.99 MHz 7.499.99 MHz 10.499.99 MHz 14.499.99 MHz 18.499.99 MHz 21.499.99 MHz 25.099.99 MHz 29.999.99 MHz 55.000.00 MHz 148.000.00 MHz
CW Transmit Frequency Accuracy Test:
Test Description: Most modern amateur equipment is surprisingly accurate in frequency. It is not uncommon to find equipment operating within a few Hz of the frequency indicated on the frequency display. However, some units, notably "analog" units, not using a phase-lock loop in the VFO design, can be off by a considerable amount. This test measures the output frequency. Unit is operated into a 50-ohm resistive load at nominal temperature and supply voltage. Frequency is also measured at minimum output power, low supply voltage (12 volt units only) and over the operating temperature range (mobile and portable units only). Non-portable equipment is not tested in the temperature chamber.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 7
Test Results: Unit Frequency 14.000.00 MHz 14.000.00 MHz 14.000.00 MHz 14.000.00 MHz
Supply Voltage 13.8 V 11.5 V 13.8 V 13.8 V
Temperature 25 C 25C -10C +60C
Measured Frequency Full Output Power 14.000.027 MHz N/A N/A N/A
Notes: 99. Temperature chamber tests and 11.5 volt tests are generally performed only for portable and mobile equipment.

Spectral Purity Test:

Test Description: All transmitters emit some signals outside their assigned frequency or frequency range. These signals are known as spurious emissions or "spurs." Part 97 of the FCC rules and regulations specify the amount of spurious emissions that can be emitted by a transmitter operating in the Amateur Radio Service. The ARRL Laboratory uses a spectrum analyzer to measure the spurious emission on each band on which a transmitter can operate. The transmitter is tested across the band and the worst-case spectral purity on each band is captured from the spectrum analyzer and stored on disk. Spectral purity is reported in dBc, meaning dB relative to the transmitted carrier. The graphs and tables indicate the relative level of any spurious emissions from the transmitter. The lower that level, expressed in dB relative to the output carrier, the better the transmitter is. So a transmitter whose spurious emissions are -60 dBc is spectrally cleaner than is one whose spurious emissions are -30 dBc. FCC Part 97 regulations governing spectral purity are contained in 97.307 of the FCC rules. Information about all amateur rules and regulations is found in the ARRL FCC Rule Book. Additional information about the decibel is found in the ARRL Handbook. Key Test Conditions: Unit is operated at nominal supply voltage and temperature. Output power is adjusted to full power on each amateur band. A second measurement is taken at minimum power to ensure that the spectral output is still legal at low power. The level to the spectrum analyzer is - 10 dBm maximum. The resolution bandwidth of the spectrum analyzer is 10 kHz on HF, 100 kHz on VHF, MHz on UHF. Block Diagram:
CAUTION!: Power must only be applied to the attenuator input! Do not reverse input and output terminals of the Bird 8329.
TELEGRAPH KEY POWER SOURCE
RF Power Attenuator & Dummy Load Bird 8329
10 dB STEP ATTENUATOR HP 355D
1 dB STEP ATTENUATOR HP 3555C

DO NOT EXCEED 0 dBm

SPECTRUM ANALYZER HP 8563E
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 8

Spectral-Purity Graphs:

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 9
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 10
Transmit Two-Tone IMD Test:
Test Description: Investigating the sidebands from a modulated transmitter requires a narrow-band spectrum analysis. In this test, a two-tone test signal is used to modulate the transmitter. The display shows the two test tones plus some of the IMD products produced by the SSB transmitter. In the ARRL Lab, a two-tone test signal with frequencies of 700 and 1900 Hz is used to modulate the transmitter. These frequencies were selected to be within the audio passband of the typical transmitter, resulting in a meaningful display of transmitter IMD. The intermodulation products appear on the spectral plot above and below the two tones. The lower the intermodulation products, the better the transmitter. In general, it is the products that are farthest removed from the two tones (typically > 3 kHz away) that cause the most problems. These can cause splatter up and down the band from strong signals. Key Test Conditions: Transmitter operated at rated output power. Audio tones and drive level adjusted for best performance. Audio tones 700 and 1900 Hz. Both audio tones adjusted for equal RF output. Level to spectrum analyzer, - 10 dBm nominal, -10 dBm maximum. Resolution bandwidth, 10 Hz Block Diagram:

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 11

Transmit IMD Graphs

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 12
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 13
SSB Carrier and Unwanted Sideband Suppression Test:
Test Description: The purpose of the SSB Carrier and opposite-sideband Suppression test is to determine the level of carrier and unwanted sideband suppression relative to Peak Envelope Power (PEP). The transmitter output is observed on the spectrum analyzer and the unwanted components are compared to the desired sideband. The level to the spectrum analyzer is -10 dBm nominal. The measurement bandwidth is 100 Hz. The greater the amount of suppression, the better the transmitter. For example, opposite sideband suppression of 60 dB is better than suppression of 50 dB. Test Results: Frequency 14.2 MHz USB/LSB 50.2 MHz USB/LSB 144.2 MHz USB/LSB Carrier Suppression < -50/-44 dB PEP < -60/-65 dB PEP < -58/-56 dB PEP Opposite Sideband Suppression < -70/-70 dB PEP < -70/-70 dB PEP < -70/-70 dB PEP Notes

CW Keying Waveform Test:

Test Description: The purpose of the CW Keying Waveform Test is to determine the rise and fall times for the 10% to the 90% point of the device under test's RF output envelope in the CW mode. The on and off delay times from key closure to RF output are also measured. If the transmitter under test has several CW modes, (i.e. VOX, QSK) these measurements is made at rated output power for each mode. A picture of the oscilloscope screen is taken of the results with the QSK off, and in the VOX mode showing the first dit, and any other test conditions that result in a waveshape that is significantly different from the others (more than 10% difference, spikes, etc.). The first and second dits are shown in all modes. If the risetime or falltime become too short, the transmitter will generate key clicks. Most click-free transmitters have a rise and fall time between 1 ms and 5 ms. The absolute value of the on delay and off delay are not critical, but it is important that they be approximately the same so that CW weighting will not be affected. Some transmitters used in the VOX mode exhibit a first dit that is shorter than subsequent dits. Other transmitters can show significant shortening of all dits when used in the QSK mode. The latter will cause keying to sound choppy. The first dit foreshortening is expressed as a "weighting" number. In perfect keying, the weighting is 50%, meaning that the carrier is ON for 50% of the time.

Key Test Conditions:

The transmitter is operated at room temperature at rated output power into a 50-ohm resistive load. The power supply voltage is nominal. Attenuators are adjusted to obtain 3 volts RMS to the oscilloscope. Test Result Summary: Frequency First Dit Risetime 14.02 MHz Semi-QSK 1.0 ms 14.02 MHz QSK 1.0 ms Mode First Dit Subsequent Falltime Dits Risetime 1.5 ms 2.0 ms 1.5 ms 2.0 ms Subsequent Dits Falltime 1.5 ms 1.5 ms On Off Weighting First Dit Delay Delay % Weightin g% 9 ms 3 ms 44.4% 41.7% 9 ms 3 ms 34.7% 41.7%
Captions (Figures on next pages): All Figures are 10 ms/division., unless otherwise noted. Figure 1. This shows the first and second dits in semi break-in mode. Figure 2. This shows the first and second dits in full break-in mode (QSK).
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 14

CW Keying Waveforms:

Figure 1

Figure 2

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 15
Transmit Keyer Speed Test:
Test Description: This test measures the speed of the internal keyer on transmitters so equipped. The keyer is tests at minimum, midrange and maximum speeds and the time from dit to dit is measured using an oscilloscope and used to calculate the speed using the "Paris" method of code speed calculation. (In the Paris method, the word "Paris" is used as the standard word to calculate words per minute.) Test Results: Min WPM 6 wpm Notes:

Max WPM 67 wpm

Mid WPM 25 wpm

Keying sidetone test:

Test Description: This test measures the audio frequency of the keyer sidetone. Test Result: Default pitch 700 Hz Notes:

Minimum 298 Hz

Maximum 893 Hz
Transmit/Receive Turnaround Test:
Test Description: The purpose of the Transmit/Receive turnaround test is to measure the delay required to switch from the transmit to the receive mode of a transceiver. Test Results: Frequency Conditions T/R Delay AGC Fast T/R Delay AGC Slow 14.2 MHz 50% audio 21.0 ms 21.0 ms Notes: 1. T/R delay less than or equal to 35 ms is suitable for use on AMTOR. 2. Times on 6M and 2M are similar.

Receive Frequency Range:

Test Description: This test measures the tuning range of the receiver. The range expressed is the range over which the receiver can be tuned. Most receivers exhibit some degradation of sensitivity near the limits of their tuning range. In cases where this degradation renders the receiver unusable, we report both the actual and useful tuning range. Test Results: Minimum Frequency
30 kHz 174.000.00 MHz Notes: 1. Tuning ranges: 30 kHz - 60 MHz, 108 MHz - 174 MHz. Test Results Frequency 30 kHz 100 kHz 200 kHz 500 kHz 57 MHz 59.995 MHz 108 MHz 174 MHz
Minimum Frequency MDS -70.5 dBm

Maximum Frequency

Maximum Frequency MDS -139.0 dBm
Sensitivity Preamp OFF -70.5 dBm -105.0 -112.6 -119.0 -118.5 -106.0 -139.0 -139.0
Notes: 1. Sensitivity degrades gradually between 57 and 60 MHz. 2. There is an S8 birdie on 60.0 MHz exactly.

AM Sensitivity Test:

Test Description: The purpose of the AM receive Sensitivity Test is to determine the level of an AM signal, 30% modulated at 1 kHz, that results in a tone 10 dB above the noise level (MDS) of the receiver. Two frequencies, 1.020 MHz and 3.800 MHz are used for this test. The more negative the number, expressed in dBm, or the smaller the number expressed in voltage, the better the sensitivity.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 20
Test Results: Frequency 1.02 MHz 1.02 MHz 1.02 MHz 3.8 MHz 3.8 MHz 3.8 MHz 50.2 MHz 50.2 MHz 50.2 MHz 144.2 MHz 144.2 MHz 144.2 MHz 120.01 MHz (aircraft) 120.01 MHz 120.01 MHz
Preamplifier OFF ONE TWO OFF ONE TWO OFF ONE TWO OFF ONE TWO OFF ONE TWO
uV 4.12 N/A N/A 1.4 0.61 0.46 1.90 0.78 0.52 0.72 0.43 N/A 1.1 0.58 N/A

Notes 1 1

Notes: 0. NAR Disabled. 1. Preamp not available at 1 MHz. 2. Only one preamp (108-174 MHz).
FM SINAD and Quieting Test:
Test Description: The purpose of the FM SINAD and Quieting Test is to determine the following at a test

frequency of 29.000 MHz:

1) The 12 dB SINAD value. SINAD is an acronym for "SIgnal plus Noise And Distortion" and is a measure of signal quality. The exact expression for SINAD is the following: SINAD = Signal + Noise + Distortion Noise + Distortion (expressed in dB)
If we consider distortion to be merely another form of noise, (distortion, like noise, is something unwanted added to the signal), we can further reduce the equation for SINAD to: SINAD = Signal + Noise Noise (expressed in dB)

If we now consider a practical circuit in which the signal is much greater than the noise, the value of the SIGNAL + NOISE can be approximated by the level of the SIGNAL alone. The SINAD equation then becomes the signal to noise ratio. The approximation now becomes: SINAD = Signal Noise (expressed in dB)
For the 25% level of distortion used in this test, the SINAD value can be calculated as follows: SINAD = 20 log (1/25%) = 20 log 4 = 12 dB 2) The level of unmodulated input signal that produces 10 dB of quieting if specified by the manufacturer. 3) The level of unmodulated input signal that produces 20 dB of quieting if specified by the manufacturer. ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 21
The more negative the number, expressed in dBm, or the smaller the number, expressed as voltage, the better the sensitivity. Test Results:
Frequency 29.0 MHz 29.0 MHz 29.0 MHz 29.0 MHz 29.0 MHz 29.0 MHz 52.0 MHz 52.0 MHz 52.0 MHz 52.0 MHz 52.0 MHz 52.0 MHz 146.0 MHz 146.0 MHz 146.0 MHz 146.0 MHz 146.0 MHz 146.0 MHz
Preamplifier OFF ONE TWO OFF ONE TWO OFF ONE TWO OFF ONE TWO OFF ONE TWO OFF ONE TWO
Bandwidth 9 kHz 9 kHz 9 kHz 15 kHz 15 kHz 15 kHz 9 kHz 9 kHz 9 kHz 15 kHz 15 kHz 15 kHz 9 kHz 9 kHz 9 kHz 15 kHz 15 kHz 15 kHz
uV 0.53 0.21 0.15 0.62 0.25 0.18 0.66 0.26 0.18 0.81 0.30 0.21 0.26 0.17 N/A 0.30 0.19 N/A
Notes: 1. Level for 12 dB SINAD. The FM quieting test is performed only if needed to verify a manufacturer's specification.
Blocking Dynamic Range Test:
Test Description: Dynamic range is a measurement of a receiver's ability to function well on one frequency in the presence of one or more unwanted signals on other frequency. It is essentially a measurement of the difference between a receiver's noise floor and the loudest off-channel signal that can be accommodated without measurable degradation of the receiver's response to a relatively weak signal to which it is tuned. This difference is usually expressed in dB. Thus, a receiver with a dynamic range of 100 dB would be able to tolerate an off-channel signal 100 dB stronger than the receiver's noise floor. In the case of blocking dynamic range, the degradation criterion is receiver desense. Blocking dynamic range (BDR) is the difference, in dB, between the noise floor and a off-channel signal that causes 1 dB of gain compression in the receiver. It indicates the signal level, above the noise floor, that begins to cause desensitization. BDR is calculated by subtracting the noise floor from the level of undesired signal that produces a 1-dB decrease in a weak desired signal. It is expressed in dB. The greater the dynamic range, expressed in dB, the better the receiver performance. It is usual for the dynamic range to vary with frequency spacing. Key Test Conditions: AGC is normally turned off; the receiver is operated in its linear region. Desired signal set to 10 dB below the 1-dB compression point, or 20 dB above the noise floor in receivers whose AGC cannot be disabled. The receiver bandwidth is set as close as possible to 500 Hz.

Test Result Summary: Band Spacing 1.82 MHz 3.52 MHz 3.52 MHz 7.02 MHz 14.02 MHz 14.02 MHz 14.02 MHz 21.02 MHz 28.02 MHz 50.02 MHz 50.02 MHz 144.02 MHz 144.02 MHz 50 kHz 20 kHz 50 kHz 50 kHz 20 kHz 50 kHz 100 kHz 50 kHz 50 kHz 20 kHz 50 kHz 20 kHz 50 kHz
Preamp OFF IMD DR (dB) N/A 99 N/A N/A 99 N/A 104 N/A N/A 97 N/A 89 N/A
Preamp ON1 IMD DR (dB) 89

Notes 2, 3

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 24
Notes: 1. Both preamps on. 2. Unit tested at 500 Hz bandwidth. 3. All dynamic range figures are from the second unit, serial number 001055, as these were more typical of the performance of most IC-746s. The original unit was being repaired by the factory at time this report was being written. * Indicates that the measurement was noise limited at values shown.

Dynamic Range Graphs:

The following page shows one of the highlights of ARRL test result reports -- swept graphs on receiver two-tone, third-order IMD dynamic range and blocking dynamic range. These graphs are taken using National Instruments LabWindows CVI automated test software, with a custom program written by the ARRL Laboratory. Dynamic range measures the difference between a receiver's noise floor and the receiver's degradation in the presence of strong signals. In some cases, the receiver's noise performance causes receiver degradation before blocking or a spurious response is seen. In either case, if the noise floor is degraded by 1 dB due to the presence of receiver noise during the test, the dynamic range is said to be noise limited by the level of signal that caused the receiver noise response. A noise-limited condition is indicated in the QST "Product Review" test-result tables. The Laboratory is working on software changes that will show on the test-result graphs which specific frequencies were noise limited. These will be incorporated into future testresult reports. Being "noise limited" is not necessarily a bad thing. A receiver noise limited at a high level is better than a receiver whose dynamic range is lower than the noise-limited level. In essence, a receiver that is noise limited has a dynamic range that is better than its local-oscillator noise. Most of the best receivers are noise limited at rather high levels. The ARRL Laboratory has traditionally used off-channel signals spaced 20 kHz from the desired signal. This does allow easy comparisons between different receivers. There is nothing magical about the 20-kHz spacing, however. In nearly all receivers, the dynamic range varies with signal spacing, due to the specific design of the receiver. Most receivers have filter combinations that do some coarse filtering at RF and in the first IF, with additional filtering taking place in later IF or AF stages. As the signals get "inside" different filters in the receiver, the dynamic range decreases as the attenuation of the filter is no longer applied to the signal. Interestingly, the different filter shapes can sometimes be seen in the graphs of dynamic range of different receivers. In the case of the ARRL graphs, one can often see that the 20-kHz spacing falls on the slope of the curve. Many manufacturers specify dynamic range at 50 or 100 kHz. The computer is not as skilled (yet) at interpreting noisy readings as a good test engineer, so in some cases there are a few dB difference between the computer-generated data and those in the "Product Review" tables. Our test engineer takes those number manually, carefully measuring levels and interpreting noise and other phenomena that can effect the test data. (We are still taking the two-tone IMD data manually.) The graphs that follow show swept blocking and two-tone dynamic range. In the blocking test, the receiver is tuned to a signal on 14.020 MHz, the center of the graph. The X axis is the frequency (MHz) of the undesired, off-channel signal. In the two-tone test, the receiver is tuned to a signal on 14.020 MHz, the center of the graph. The X axis is the frequency of the closer of the two tones that are creating intermodulation.

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 25

Dynamic-Range Graphs:

Swept Blocking Dynamic Range
Swept Two-Tone, Third-Order IMD Dynamic Range
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 26

Second-Order IMD Test:

Test Description: This test measures the amount of 2nd-order mixing that takes place in the receiver. Signals at 6 and 8 MHz are presented to the receiver and the resultant output at 14 MHz is measured. Test Results: Frequency Preamplifier Mode IP2 (dBm) 14.02 MHz OFF CW +47 14.02 MHz ON CW +60 Notes: 1. This figure is the same for both preamps. Notes 1
In-Band Receiver IMD Test:
Test Description: This test measures the intermodulation that occurs between two signals that are simultaneously present in the passband of a receiver. Two signals, at levels of 50 uV (nominally S9), spaced 100 Hz are used. The receiver AGC is set to FAST. The receiver is tuned so the two signals appear at 900 Hz and 1100 Hz in the receiver audio. The output of the receiver is viewed on a spectrum analyzer and the 3rd- and 5th order products are measured directly from the screen. The smaller the products as seen on the graph, the better the receiver. Generally, products that are less than 30 dB below the desired tones will not be cause objectionable receiver intermodulation distortion. Key Test Conditions: S9 or S9 + 40 dB signals Receiver set to SSB normal mode, nominal 2 - 3 kHz bandwidth Block Diagram:
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 27
In-Band Receiver IMD Graphs:
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 28
FM Adjacent Channel Selectivity Test:
Test Description: The purpose of the FM Adjacent Channel Selectivity Test is to measure the ability of the
device under test receiver to reject interference from individual undesired signals while receiving various levels of desired signal. The desired carrier signal will be at 29.000 MHz, modulated at 1000 Hz, and the offending signal will be located at adjacent nearby frequencies with 400 Hz modulation. (NOTE: The SINAD Test in 5.3 must be performed before this test can be completed.) The greater the number in dB, the better the rejection.

Test Results: Frequency 29.0 MHz 52 MHz 146 MHz Notes: Preamplifier ON ON ON Frequency Spacing 20 kHz 20 kHz 20 kHz Adjacent-channel rejection (dB) 71 Notes
FM Two-Tone 3rd-Order Dynamic Range Test:
Test Description: The purpose of the FM Two-Tone 3rd Order Dynamic Range Test is to determine the range of signals that can be tolerated by the device under testing the FM mode while producing no spurious responses greater than the 12-dB SINAD level. To perform this test, two signals, f1 and f2, of equal amplitude and spaced 20 kHz apart, are injected into the input of the receiver. The signal located 40 kHz from the distortion product being measured is modulated at 1,000 Hz with a deviation of 3 kHz. The receiver is tuned to the Third Order IMD frequencies as determined by (2f1-f2) and (2f2-f1). The input signals are then raised simultaneously by equal amounts until 25 % distortion, or the 12 dB SINAD point, is obtained. Frequencies 10 MHz outside the amateur band are used to test the wide-band dynamic range. The greater the dynamic range, the better the receiver performance. Test Results: Frequency 29 MHz 52 MHz 52 MHz 146 MHz 146 MHz Preamplifier ON ON ON ON ON Frequency Spacing 20 kHz 20 kHz 10 MHz 20 kHz 10 MHz Dynamic Range (dB) 64* 72* -71* 82 Notes 1, 2 3
Notes: 1. FM Narrow for all tests in this table. 2. All FM dynamic range data is from the second unit, serial number 001055. 3. A third-order product could not be obtained at 10 MHz tone spacings on 52 MHz. This is most likely due to the lack of receive coverage between 60 and 108 MHz (the tones used are 62 and 72 MHz). * Test is noise limited. In FM, this results in a reading that is somewhat inaccurate. The actual dynamic range is probably a few dB worse than the figures indicated. While this sounds opposite of what one would expect, because the test is based on a SINAD measurement, the presence of noise means that it takes a stronger signal to have a product equal to the measured noise floor, resulting in a number that appears better than it would be if there were no noise.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 29

Image Rejection Test:

Test Description: This test measures the amount of image rejection for superhetrodyne receivers by determining the level of signal input to the receiver at the first IF image frequencies that will produce an audio output equal to the MDS level. The test is conducted with the receiver in the CW mode using the 500 Hz, or closest available, IF filters. Any audio filtering is disabled and AGC is turned OFF, if possible. The test is performed with the receiver tuned to 14.020 MHz for receivers that have 20-meter capability, or to a frequency 20 kHz up from the lower band edge for single-band receivers. The greater the number in dB, the better the image rejection. Test Results: Frequency

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 31

S-Meter Test:

Test Description: The purpose of the S-Meter Test is to determine the level of RF input signal required to produce an S9 and S9+20 dB indication on the receiver S meter. This test is performed with the receiver in the CW mode at a frequency of 14.200 MHz. The IF filter is set to 500 Hz, nominal. A traditional S9 signal is a level of 50 uV (an old Collins receiver standard). The Collins standard S unit was 6 dB. This is , however, not a hard and fast rule, especially for LED or bargraph type S meters. Test Results: Frequency 1.02 MHz 14.2 MHz 14.2 MHz 14.2 MHz 52 MHz 52 MHz 52 MHz 146 MHz 146 MHz
Preamplifier OFF OFF ONE TWO OFF ONE TWO OFF ON
S Units S9 S9 S9 S9 S9 S9 S9 S9 S9
uV 243 77.6 23.7 7.27.9 13.8 32.0 10.1

Notch Filter Test:

Test Description: This test measures the notch filter depth at 1 kHz audio and the time required for auto-notch DSP filters to detect and notch a signal. The more negative the notch depth number, the better the performance. Test Results: Frequency Notch Depth Notes 1
Notes: 1. Unit does not have a notch filter.
Other Tests: Temperature Chamber Test Description:
All equipment that would normally be used outdoors are subjected to a function, output power and frequency accuracy test over its specified temperature range. For those units not specified, the unit is operated at -10 and +60 degrees Celsius. These temperatures were chosen to represent typical specifications and typical outdoor use over most of the country.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Serial: 001674 Copyright 1998, American Radio Relay League, Inc. All Rights Reserved. Page 32