ARRL Laboratory Expanded Test-Result Report ICOM IC-746 Pro
Prepared by: American Radio Relay League, Inc. Technical Department Laboratory 225 Main St. Newington, CT 06111 Telephone: (860) 594-0214 Internet: mtracy@arrl.org Order From: American Radio Relay League, Inc. Technical Department Secretary 225 Main St. Newington, CT 06111 Telephone: (860) 594-0278 Internet: reprints@arrl.org Price: $7.50 for ARRL Members, $12.50 for non-Members, postpaid. Model Information: IC-746 Pro Serial #: 01484 QST "Product Review" May, 2002 Manufacturer: ICOM America 2380 116th Ave NE PO Box C-90029 Bellevue, WA 98004 Telephone: 425-454-8155
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 1

Table of Contents:

Introduction.....3 Transmitter Output Power....4 Transmitter Output Power Results....5 Current Consumption.....5 Transmit Frequency Range....6 CW Transmit Frequency Accuracy....6 Spectral Purity.....7 Spectral-Purity Graphs....8 Transmit Two-Tone IMD.....11 Transmit IMD Graphs.....12 SSB Carrier and Unwanted Sideband Suppression...15 CW Keying Waveforms and Sidebands....15 Keying Waveforms....16 Keying Sideband Plots....16 CW Keyer Speed Range.....19 Keyer Sidetone Frequency....19 Transmit/Receive Turnaround Time....19 Transmit Delay Time....19 Transmit Composite Noise....20 Transmit Composite Noise Graphs...20 Receiver Noise Floor....21 Receive Frequency Range....22 AM Sensitivity....23 FM SINAD.....23 Antenna Port Isolation....24 Blocking Dynamic Range....24 Two-Tone 3rd-Order IMD Dynamic Range....26 Third-Order Intercept....27 Swept Dynamic Range Graphs....28 Second-Order Intercept....30 In-Band Receiver IMD....30 FM Adjacent Channel Selectivity....31 FM Two-Tone 3rd-Order Dynamic Range...32 IF and Image Rejection....32 Audio Output Power.....33 Audio Hiss.....33 IF and Audio Frequency Response...33 Squelch Sensitivity.....34 S-Meter Sensitivity....34
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 2

Introduction

This document summarizes the extensive battery of tests performed by the ARRL Laboratory for each unit that is featured in QST "Product Review." For all tests, there is a discussion of the test and test method used in ARRL Laboratory testing. For most tests, critical conditions are listed to enable other engineers to duplicate our methods. For some of the tests, a block diagram of the test setup is included. The ARRL Laboratory has a document, the ARRL Laboratory Test Procedures Manual, that explains our specific test methods in detail. While this is not available as a regular ARRL publication, it may be downloaded from our web page. Most of the tests used in ARRL product testing are derived from recognized standards and test methods. Other tests have been developed by the ARRL Lab. The ARRL Laboratory test equipment is calibrated annually, with traceability to National Institute of Standards and Technology (NIST). The units being tested are operated as specified by the equipment manufacturer. Equipment that can be operated from 13.8 volts (nominal) is also tested for function, output power and frequency accuracy at the minimum specified voltage, or 11.5 volts if not specified. Also, units that are capable of mobile or portable operation are tested at their rated temperature range, or at 10 to +60 degrees Celsius in a commercial temperature chamber. ARRL "Product Review" testing represents a sample of only one unit (although we sometimes obtain an extra sample or two for comparison purposes). This is not necessarily representative of all units of the same model number. It is not uncommon that some parameters will vary significantly from unit to unit. The ARRL Laboratory and Product Review editor work with manufacturers to resolve any deviation from specifications or other problems encountered in the review process. These problems are documented in the Product Review.

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 3

Transmitter Output Power

Test description: One of the first things an amateur wants to know about a transmitter or transceiver is its RF output power. The ARRL Lab measures the CW output power for every band on which a transmitter can operate. The equipment is also tested on one or more bands for any other mode of operation for which the transmitter is capable. Another purpose of the Transmitter Output-Power Test is to measure the dc current consumption at the manufacturer's specified dc-supply voltage, if applicable. Many transmitters are de-rated from maximum output power on full-carrier AM and FM modes. In most cases, a 100-watt CW/SSB transmitter may be rated at 25 watts carrier power on AM. The radio may actually deliver 100 watts PEP in AM or FM but is not specified to deliver that power level for any period of time. In almost all cases, the linearity of a transmitter decreases as output power increases. A transmitter rated at 100 watts PEP on single sideband may actually be able to deliver more power, but as the power is increased beyond the rated RF output power, adjacent channel splatter (IMD) usually increases dramatically. Key Test Conditions: Termination: 50 ohms resistive, or as specified by the manufacturer. Block Diagram:

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 4381

POWER SUPPLY

DC ONLY

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 4
Transmitter Output Power Results
NOTE!: If comparing this table against the table from the IC-746 (Sept 98 QST), please be sure you have a recent copy of the expanded report for the IC-746, as the original report contained incorrect data for the high power output. Frequency Mode Unit Measured Unit Measured Notes Band Minimum Minimum Maximum Maximum Power (W) Power (W) Power (W) Power (W) 1.8 MHz CW See note 1 2.0 W 100 103.4 W 1, 2 3.5 MHz CW 2.2 107.7 3.5 MHz AM 1.0 39.1 W carrier 7.0 MHz CW 2.2 109.8 10.1 MHz CW 2.3 110.MHz CW 2.3 110.MHz USB 2.2 108.MHz CW 2.3 110.MHz CW 2.2 107.MHz CW 2.2 109.MHz CW 2.2 109.MHz FM 2.3 110.MHz CW 1.8 103.MHz FM 2.3 105.MHz AM 1.2 38.6 W carrier 50 MHz SSB 2.1 103.MHz CW 2.4 97.MHz FM 2.9 98.MHz AM 1.3 39.5 W carrier 144 MHz SSB 2.6 97.1 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.

Current Consumption

(DC-powered units only)
Test Description: Current consumption can be important to the success of mobile and portable operation. 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. Current Consumption: Voltage Transmit Output Power Current 13.8 V 19.8 A 110.7 W Receive Current 1.9 A Lights? ON Notes
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 5

Transmit Frequency Range

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. Most modern synthesized transmitters are capable of operation outside the ham bands, but spectral purity is not always legal outside the 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.MHz 3.MHz 7.MHz 10.MHz 14.MHz 18.MHz 21.MHz 24.MHz 28.MHz 50.MHz 144.MHz High-Frequency Limit 1.MHz 3.MHz 7.MHz 10.MHz 14.MHz 18.MHz 21.MHz 24.MHz 29.MHz 54.MHz 148.MHz Notes
CW Transmit Frequency Accuracy
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. 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. Test Results: Unit Display Supply Temperature Measured Frequency Frequency Voltage Full Output Power 14.MHz 13.8 V 25 C 13.MHz 50.MHz 13.8 V 25 C 49.MHz 144.MHz 13.8 V 25 C 143.MHz Notes: 1. Measured frequency at low power output was 7 Hz lower on 2M. Notes

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 6

Spectral Purity

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 saved to a file 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, 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. 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 resolution bandwidth of the spectrum analyzer is 10 kHz on HF, 100 kHz on VHF, 1 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 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 7

Spectral-Purity Graphs

Reference Level: 0 dBc

30 Frequency (MHz)

ICOM IC-746 Pro, s/n 01484 1.8 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRSLO.TXT
ICOM IC-746 Pro, s/n 01484 7.0 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS40.TXT

60 Frequency (MHz)

ICOM IC-746 Pro, s/n 01484 3.5 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS80.TXT
ICOM IC-746 Pro, s/n 01484 10.1 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS30.TXT
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 8
ICOM IC-746 Pro, s/n 01484 14.0 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS20.TXT
ICOM IC-746 Pro, s/n 01484 21.0 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS15.TXT
ICOM IC-746 Pro, s/n 01484 18.1 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS17.TXT
ICOM IC-746 Pro, s/n 01484 24.9 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS12.TXT
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 9

Frequency (MHz)

900 1000
ICOM IC-746 Pro, s/n 01484 28.0 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS10.TXT
ICOM IC-746 Pro, s/n 01484 144.0 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS2M.TXT
ICOM IC-746 Pro, s/n 01484 50.0 MHz Band, Spectral Purity, 100 W I:\PRODREV\TESTS\IC746PRO\746PRS6M.TXT
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 10

Transmit Two-Tone IMD

Test Description: Investigating the sidebands from a modulated transmitter requires a narrow-band spectrum analysis. In this test, a two-tone signal is used to modulate the transmitter. The spectral display shows the test tones plus some of the IMD products produced by the SSB transmitter. In the ARRL Lab, 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 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. Both audio tones adjusted for equal RF output. Level to spectrum analyzer, 10 dBm maximum. Resolution bandwidth, 10 Hz Block Diagram:

Keying Waveforms

Figure 1A

Keying Sideband Plots

Figure 1B
14022 Frequency Sweep: +/- 5 kHz 14024

Figure 2A

Figure 2B

Figure 3A

Figure 3B
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 16

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 6A

Figure 6B
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 17

Figure 7A

Figure 7B

Figure 8A

Figure 8B
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 18

CW Keyer Speed Range

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 6.2 wpm Max WPM 40 wpm Mid WPM 25 wpm Notes

Keyer Sidetone Frequency

Test Description: This test measures the audio frequency of the keyer sidetone. Test Result: Default pitch 625 Hz Minimum 300 Hz Maximum 900 Hz Notes
Transmit/Receive Turnaround Time
Test Description: The purpose of the Transmit/Receive turnaround test is to measure the delay required to switch from transmit mode to receive mode. Test Results: Frequency T/R Delay AGC Fast T/R Delay AGC Slow 14.02 MHz 18.0 ms 16.0 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. Notes 1, 2

Transmit Delay Time

Test Description: The purpose of the Transmit Delay test is to measure the time between PTT closure and 50% RF output. It is measured on SSB, modulated with a single tone and on FM, unmodulated. Test Results: Frequency 14.2 MHz 29.2 MHz 50.2 MHz 144.2 MHz Mode SSB FM FM FM Delay 35.0 ms 12 ms 12 ms 14 ms Notes

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 19

Transmit Composite Noise

Test Description: The purpose of the Composite-Noise Test is to observe and measure the phase and amplitude noise, as well as any spurious signals generated by the device under test transmitter. Since phase noise is the primary noise component in any well-designed transmitter, it can be assumed, therefore, that almost all the noise observed during this test is phase noise. This measurement is accomplished by converting the output of the transmitter down to a frequency about 10 or 20 Hz above baseband. A mixer and a signal generator used as a local oscillator are used to perform this conversion. Filters remove the dcomponent as well as the unwanted heterodyne components. The remaining noise and spurious signals are then observed on the spectrum analyzer. The lower the noise as seen on the plot, the better the transmitter. Key Test Conditions: Transmitter operated at rated output power into a 50-ohm resistive load. Transmitter operated at room temperature. Frequencies from 2 to 22 kHz from the carrier are measured. Ten sweeps are averaged on the spectrum analyzer to reduce noise. Block Diagram:
CAUTION!: POWER MUST ONLY BE APPLIED TO THE ATTENUATOR INPUT! DO NOT REVERSE THE INPUT AND OUTPUT TERMINALS OF THE BIRD 8329. RF SIGNAL GENERATOR MARCONI 4031 DUT TRANSMITTER RF WATTMETER BIRD 4381 RF POWER ATTENUATOR BIRD dB STEP ATTENUATOR HP 355D 1 dB STEP ATTENUATOR HP 355C

PHASE LOCK SIGNAL

COMPOSITE NOISE MIXER

LOW-NOISE AMPLIFIER

6 dB MIXER

ATTENUATOR

1.25 MHZ LOW PASS FILTER

1 KHZ HIGH PASS FILTER

IF OUT
Transmit Composite Noise Graphs
Reference Level: - 60 dBc/Hz Vertical Scale: dBc/Hz
Frequency Sweep: 2 to 22 kHz from Carrier
ICOM IC-746 Pro, s/n 01484 3.520 MHz, Phase Noise, 100 W I:\PRODREV\TESTS\IC746PRO\746PRP80.TXT
ICOM IC-746 Pro, s/n 01484 14.020 MHz, Phase Noise, 100 W I:\PRODREV\TESTS\IC746PRO\746PRP20.TXT
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 20
ICOM IC-746 Pro, s/n 01484 50.020 MHz, Phase Noise, 100 W I:\PRODREV\TESTS\IC746PRO\746PRP6M.TXT

30 kHz 60 MHz 108 MHz 174 MHz Notes: 1. Tuning ranges: 30 kHz - 60 MHz, 108 MHz - 174 MHz. Other Test Results Frequency Sensitivity Preamp OFF 100 kHz 109.2 dBm 250 kHz 117.2 dBm Notes
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 22

AM Sensitivity

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.
Test Results: Frequency Preamp OFF Preamp One 1.02 MHz N/A 5.89 V 3.9 MHz 1.6 V 0.623 V 53 MHz 2.16 V 0.932 V 120 MHz 5.43 V 0.976 V (aircraft) 146 MHz 1.32 V 0.530 V Notes: 1. Preamp not available at 1 MHz. 2. Only one preamp on VHF (108-174 MHz). Preamp Two N/A 0.512 V 0.602 V N/A N/A Notes 1

FM SINAD

Test Description: The purpose of the FM SINAD and Quieting Test is to determine the following: 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 The more negative the number, expressed in dBm, or the smaller the number, expressed as voltage, the better the sensitivity.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 23

SINAD Test Results:

Frequency 29.0 MHz 52.0 MHz 146.0 MHz
Preamp OFF 0.555 V 0.860 V 0.489 V
Preamp One 0.254 V 0.335 V 0.180 V
Preamp Two 0.224 V 0.214 V N/A

Notes 1

Notes: 1. 15-kHz bandwidth for all results in this table.

Antenna Port Isolation

ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 24

Block Diagram:

RF SIGNAL GENERATOR MARCONI 2041 HI-Z MONITOR AMP
2-PORT COUPLER MCL ZSFC 2-6
RF SIGNAL GENERATOR HP 8640B
Blocking Dynamic Range Test Result: Band Spacing Preamp Preamp Preamp Notes OFF One Two 1.82 MHz 50 kHz 126.5 1, 2 3.52 MHz 50 kHz 126.8 3.52 MHz 20 kHz 124.5 120.6 117.1 3.52 MHz 5 kHz 99.8 95.7 92.5 7.02 MHz 50 kHz 126.2 14.02 MHz 100 kHz 134.6 127.2 14.02 MHz 50 kHz 127.7 14.02 MHz 20 kHz 125.0 122.6 117.9 14.02 MHz 5 kHz 100.0 97.7 92.9 21.02 MHz 50 kHz 127.7 28.02 MHz 50 kHz 126.8 50.02 MHz 50 kHz 1267.8 50.02 MHz 20 kHz 126.7 124.2 120.9 50.02 MHz 5 kHz 101.1 98.8 95.7 144.02 MHz 50 kHz 117.8* N/A 144.02 MHz 20 kHz 113.7* 111.7* N/A 144.02 MHz 5 kHz 99.9 88.4 N/A Notes: 1. Receiver bandwidth set to 500 Hz for all tests. 2. 100 and 50 kHz data taken with preamp two on only (except for 144 MHz, where there is only one preamp). * Indicates that measurement was noise limited at values shown.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 25
Two-Tone 3rd-Order IMD Dynamic Range
Test Description: Two-tone IMD Dynamic Range (IMD DR) measures the impact of the intermodulation of two strong (undesired) signals within a receiver. IMD is the production of spurious responses resulting from the mixing of two or more undesired signals in a receiver. Two-Tone IMD DR is the difference, in dB, between the noise floor and the strength of two equal off-channel signals that produce a third-order product equal to the noise floor. This test determines the range of signals that can be tolerated by the receiver while producing essentially no undesired spurious responses. To perform the 3rd Order test, two signals of equal amplitude and spaced a given distance (such as 20 kHz) apart, are injected into the input of the receiver. If we call these frequencies f1 and f2, the third-order products will appear at frequencies of (2f1-f2) and (2f2-f1). The greater the dynamic range, expressed in dB, or the higher the intercept point, the better the performance. Key Test Conditions: Sufficient attenuation and isolation must exist between the two signal generators. The two-port coupler must be terminated in a load that exhibits a 20-dB or better return loss at the coupler output. The receiver is set as close as possible to a 500 Hz bandwidth. TT IMD DR Block Diagram:

Two-Tone IMD DR Test Result Summary: Band Spacing Preamp OFF 1.82 MHz 50 kHz 3.52 MHz 50 kHz 3.52 MHz 20 kHz 97.4 3.52 MHz 5 kHz 76.4 7.02 MHz 50 kHz 14.02 MHz 100 kHz 100.9 14.02 MHz 50 kHz 14.02 MHz 20 kHz 96.9 14.02 MHz 5 kHz 74.9 21.02 MHz 50 kHz 28.02 MHz 50 kHz Continued on next pg.
Preamp One 95.2 73.2 95.5 73.5
Preamp Two 91.0 92.0 91.0 71.0 91.6 93.0 92.5 92.0 71.0 93.4 91.3
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 26
Band Spacing Preamp OFF Preamp One Preamp Two Notes 50.02 MHz 50 kHz 92.9 dB 50.02 MHz 20 kHz 97.7 dB 96.1 dB 91.9 dB 50.02 MHz 5 kHz 76.7 dB 75.1 dB 72.9 dB 144.02 MHz 50 kHz 88.8 dB N/A 2 144.02 MHz 20 kHz 84.1 dB 88.8 dB N/A 2 144.02 MHz 5 kHz 75.1 dB 61.8 dB N/A 2 Notes: 1. Receiver bandwidth set to 500 Hz for all tests. 2. 100 and 50 kHz data taken with preamp two on only (except for 144 MHz, where there is only one preamp). * Indicates that measurement was noise limited at values shown.

Third-Order Intercept

Test Description: Third-order intercept (IP3) is not actually a separate test, but is part of the IMD Dynamic Range test. The third-order response of the receiver can be characterized (ideal) as a straight line with a 3:1 slope. The "on-channel" response of the receiver would be a line with a 1:1 slope. Any two lines of differing slope will have a point at which they intersect. However, the "intercept" of the third-order and on-channel responses is at a level far higher than the strength of signals receivers can normally handle. Thus, it has to be calculated rather than measured. The IP3 calculation can be based on a variety of signal levels. One common level is the noise floor (aka "mds") - however, at this level, noise can cause a non-linear response in the real-world circuits of the receiver. Also, it should be noted that IP3 is generally considered to be a measure of a receiver's strong-signal handling ability, thus it is most appropriate to calculate this with signal levels well above the noise floor. In the ARRL Lab, signal levels of S5 are used for the IP3 calculation. Third-Order Intercept Summary: Band Spacing Preamp OFF Preamp One Preamp Two Notes 3.52 MHz 20 kHz +19.15 dBm +7.25 dBm 2.25 dBm 1 3.52 MHz 5 kHz 17.60 dBm 28.75 dBm 33.75 dBm 14.02 MHz 20 kHz +20.00 dBm +9.30 dBm 1.80 dBm 14.02 MHz 5 kHz 18.25 dBm 28.2 dBm 35.55 dBm 50.02 MHz 20 kHz +22.50 dBm +12.25 dBm 1.15 dBm 50.02 MHz 5 kHz 13.50 dBm 25.25 dBm 31.15 dBm 144.02 MHz 20 kHz 6.45 dBm 5.35 dBm N/A 2 144.02 MHz 5 kHz 19.95 dBm 39.10 dBm N/A 2 Notes: 1. Receiver bandwidth set to 500 Hz for all tests. 2. 100 and 50 kHz data taken with preamp two on only (except for 144 MHz, where there is only one preamp).

IF and Image Rejection

Test Description: This test measures the amount of first IF and image rejection for superhetrodyne receivers by determining the level of signal input to the receiver at the first IF (or 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 greater the number in dB, the better the image rejection. Test Results: Frequency Preamplifier Mode CW CW CW First IF Rejection 122.5 121.2 86.1 Calculated Image Frequency 142.93 MHz 178.93 MHz 272.94 MHz Image Rejection (dB) 124.2 118.3 121.2 Notes 1
14.020 MHz ON 50.02 MHz ON 144.02 MHz ON Notes: 1. First IF is 64.455 MHz.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 32

Audio Output Power

Test Description: This test measures the audio power delivered by the receiver. The manufacturer's specification for load and distortion are used. For units not specified, an 8-ohm load and 10% harmonic distortion are used. Test Results: Specified Distortion 10% T.H.D. Specified Load Impedance 8 ohms Audio Output Power 2.3 W Notes

Audio Hiss

Test Description: This test measures the audio output power at minimum volume with no signal. It gives an indication of the noise (often referred to as "hiss") generated by the audio stages of the receiver. Test Results: Specified Load Impedance 8 ohms Hiss Level 0.165 mV (ac) Notes
IF and Audio Frequency Response
Test Description: The purpose of the IF + Audio Frequency Response Test is to measure the audio frequencies at which the receiver audio drops 6 dB from the peak signal response. The frequency-response bandwidth is then calculated by taking the difference between the lower and upper frequency. Test Results: IF Filter Use/Unit Mode Nominal Bandwidth Hz 500 WIDE WIDE NARROW Low Freq (Hz) High Freq (Hz) Difference (bandwidth) Notes 1 2
CW 588 USB 1741 LSB 2869 AM 2982 Notes: 1. High and low audio frequencies on CW vary with the pitch control. 2. 60 dB selectivity was also checked on USB, with a result of 3316 Hz.
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 33

Squelch Sensitivity

Test Description: The purpose of the Squelch Sensitivity Test is to determine the level of the input signal required to break the receiver's squelch at the threshold. This number is not usually critical. A result anywhere between 0.05 and 0.5 V is usually useful. Test Results: Frequency 29.0 MHz 52 MHz 146 MHz 14.2 MHz Preamplifier One and Two One and Two One and Two One and Two Mode FM FM FM SSB Threshold 0.070 V 0.114 V 0.092 V 6.24 V Notes

S-Meter Sensitivity

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 bandwidth is set to 500 Hz, nominal. A traditional S9 signal is a level of 50 V (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 bar-graph 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 V 240 81.5 27.5 12.30.2 15.3 57.5 6.38 Notes
ARRL Laboratory Expanded Test-Result Report Model: ICOM IC-746 Pro Serial: 01484 Copyright 2002, American Radio Relay League, Inc. All Rights Reserved. Page 34

Re: F.A. ICOM IC21A

Source: http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.boatanchors/200512/msg00157.html
From: "Dale Parfitt" <par@xxxxxxxxxxxxxxxxxx> Date: Thu, 15 Dec 2005 01:48:44 GMT
"gb" <onw9mapsgb@xxxxxxxxxxxxxxxx> wrote in message news:S6idnULIdYqy8D3eRVnqQ@xxxxxxxxxxxxxx > "Dale Parfitt" <par@xxxxxxxxxxxxxxxxxx> wrote in message > news:7LZnf.16502$OK6.6216@xxxxxxxxxxx >> It's hard for me to think of Icom as being a BA, but this qualifies, >> given its age. This was back when Icom made pretty radios. A 2M FM rig >> with both S meter and separate discriminator meter, beuatiful >> red/green/blue/white backlighting. >> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=ADME:L:LCA:US:31&item=5841063903 >> >> Tnx, >> >> Dale W4OP > Yes, I saw this auction. Sad, I remember when it and the Kenwood R599 > were new !! > > Greg > w9gb >And many more Greg. The sad part about today's rigs is that they will die a >quick death as manufacturers deplete their supplies of custom IC's and >preprogrammed memories. My keepr IC21A gets daily use fabulous audio and almost as much fun to look at as the 2B/R4C etc. Dale W4OP
References: F.A. ICOM IC21A From: Dale Parfitt Re: F.A. ICOM IC21A From: gb Re: F.A. ICOM IC21A 1
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