IC-7600 User Evaluation & Test Report
Contents
1. 0 6 30 8 50 14 60 16 max This shows an S N improvement of 10 dB with NR at maximum for an SSB signal roughly 5 dB above noise level This is an approximate measurement as the amount of noise reduction is dependent on the original signal to noise ratio 6 Manual Notch Filter MNF stopband attenuation and bandwidth In this test an RF signal is applied at a level slightly more than 70 dB above MDS The test signal is offset 1 kHz from the receive frequency to produce a test tone The MNF is carefully tuned to null out the tone completely at the receiver audio output The stopband attenuation is equal to the difference between the test signal power and MDS Test conditions 14 100 MHz USB at 70 dBm S9 2 4 kHz Sharp AGC MID preamp off ATT 0 dB NR off NB off MNF on Twin PBT neutral Results MNF nulls out signal completely Measured MDS was 125 5 dBm per Test 1 A 50 dBm test signal was applied Thus stopband attenuation 75dB 125 50 The receive frequency is now offset on either side of the null The frequencies at which the audio output rises by 6 dB are noted The 6 dB bandwidth is the difference between these two frequencies MNF 6 dB BW Wide 139 Hz Mid 100 Hz Narrow 63 Hz 12 3388 i oh R o O 858 1 p EE AEE TEE EAE T a 8 1 Fig 7 Manual Notch Filter WIDE E I 1 1 oN NM 1182. 128 138 doadnododnotwodnododwotnododwatnatnobnalnatnn 1 Fig 8 Manual Notch Filter MID 100 110 120 1 a MMM 1 _ w 1 Fig 9 Manual Notch Filter NAR The above figures depict the Manual Notch Filter stopband for Wide Mid and Narrow settings Due to the limited dynamic range of the measurement method the amplitude scale is not accurate 13 7 AGC impulse response The purpose of this test is to determine the IC 7600 s AGC response in the presence of fast rising impulsive RF events Two types of event are applied to the receiver input RF bursts with a fast rising wavefront and pulse trains with short rise times Test conditions 14 100 MHz USB for 7a 10 000 MHz for 7b 2 4 kHz SSB filter Sharp NR off NB off Preamp off for 7a Preamp 2 for 7b AGC Fast with decay time set to 0 1 sec 7a RF bursts A pulse generator applies a pulse train to the modulation input of the RF signal generator The test is performed at two steady state RF power levels 20 dBm S9 50 dB and 7 dBm S9 60 dB at 14 100 MHz The pulse generator is adjusted to generate RF bursts of 1 2 uS duration Burst rise time to 3 dBr is 200 nS Pulse period is 600 mS The IC 7600 is tuned to 14 099 MHz to produce a 1 kHz test tone at the audio output At 7 dBm the S meter peaks to S9 20 dB The result for 20 dBm is similar The AGC recovers completely in z 100 mS There is
3. OE ASA WATA AAA 2 S 0 2 8 3 8 4 8 5 8 6 8 7 kHz 8 8 Fig 12 Baseband spectral display of in band IMD products On the X axis 0 0 kHz 9999 6 kHz virtual carrier f is at 0 4 kHz f at 0 6 kHz The 3 order IMD products are at 0 2 and 0 8 kHz respectively Test Result In band IMD 10 62 52 dB B Spectrum Scope Tests Ila Spectrum Scope Sensitivity minimum visible spike In this test the RF input signal level is adjusted to produce a spike which is just visible above the scope grass level Test conditions 14 100 MHz USB SPAN 2 5 kHz SLOW sweep CENT mode ATT 0 dB Scope ATT 0 dB IF filter setting is irrelevant Minimum Visible Spike for Span 2 5 kHz 1 120 2 128 17 11b Spectrum Scope Amplitude Linearity The spectrum scope dynamic range is 70 dB Scope ATT 0 dB The scope graticule has 8 vertical divisions at 10 dB div Test conditions 14 100 MHz USB Span 2 5 kHz SLOW sweep ATT 0 dB Scope ATT 0 dB preamp off Initial input level 110 dBm The vertical amplitude is noted for each 10 dB increase in input level The scope display tracks the input signal power accurately over the entire 70 dB range 12 Spectrum Scope Resolution Bandwidth In a spectrum analyzer the resolution bandwidth RBW determines how far apart in frequency two or more signals must be to be resolved into separate and distinct displays on the screen
4. RF lab March 17 23 2009 A Receiver Tests 1 MDS Minimum Discernible Signal is a measure of ultimate receiver sensitivity In this test MDS is defined as the RF input power which yields a 3 dB increase in the receiver noise floor as measured at the audio output Test conditions ATT off NR off NB off Levels in dBm 3 6 MHz 14 1 MHz __ 50 1 MHz Preamp SSB2 4kHz CW500Hz SSB 24 kHz CW500Hz SSB 2 4kHz CW500Hz off 125 5 132 5 125 131 125 133 1 133 5 140 131 5 140 134 141 2 134 5 142 133 5 142 136 142 5 la AM Sensitivity Here an AM test signal with 30 modulation at 1 kHz is applied to the RF input The RF input power which yields 10 dB S N N is recorded Test conditions ATT off NR off NB off Wide 9 kHz filter Levels in dBm Preamp 0 9 MHz 3 9 MHz 14 1 MHz_ off 105 107 105 1 113 5 114 113 2 116 116 115 Note No RF attenuation below 1 6 MHz 2 Reciprocal Mixing Noise occurs in a superheterodyne receiver when the noise sidebands of the local oscillator LO mix with strong signals close in frequency to the wanted signal producing unwanted noise products at the IF and degrading the receiver sensitivity Reciprocal mixing noise is a measure of LO spectral purity In this test a strong undesired signal is injected into the receiver s RF input at a fixed offset from the operating frequency Th
5. Test conditions Span 2 5 kHz SLOW sweep ATT 0 dB Scope ATT 0 dB preamp off Calibration Marker is on To measure RBW a test signal is injected into the antenna input at a level sufficient to produce a spike whose vertical amplitude is equal to that of the Calibration Marker Initially the test signal is approx 10 kHz above the selected Marker spike Example Marker at 14100 kHz test signal at 14110 kHz To ensure an accurate amplitude display sweep speed is set to SLOW for all SPAN settings For each SPAN value the test signal is moved closer to the Marker spike until two distinct spikes are just observable Span kHz RBW Hz 2 5 100 5 200 10 500 25 1k 50 1k 100 2 5k 250 4k C Transmitter Tests 13 CW Power Output In this test the RF power output into a 50Q load is measured at 14 00 MHz in CW or RTTY mode at a primary DC supply voltage of 13 8V and with Drive set at 50 default RF Power Po Meter Power oo A Freq MHz 3 6 14 1 50 1 13a Transverter Jack Power Output The RF output into a 50Q load is measured at 14 00 MHz in RTTY mode at the X VERTER jack RF Power Min 50 Max Meas dBm 15 5 1 18 14 SSB Peak Envelope Power PEP Here an oscilloscope is loosely coupled to the IC 7600 RF output via a line sampler At 100W CW the line sampler is adjusted for a peak t
6. from the receive frequency to produce a test tone While tuning the signal generator across the IF passband the frequency and audio level are noted at several points on the filter flank Test conditions 10 000 MHz SSB 2 4 kHz filter 6 kHz roofing filter preamp off AGC off ATT off NR off NB off Input signal level 99 dBm 6 dB below measured 93 dBm AGC threshold Roll off in dB 250 3 6 5 300 3 5 5 400 0 4 5 500 0 3 750 0 1 2000 1 5 1 2 2500 2 5 5 5 2700 3 7 5 Fig 1 2 4 kHz SSB filter Sharp Fig 2 2 4 kHz SSB filter Soft Fig 3 500 Hz CW filter Sharp BPF 10 Fig 4 500 Hz CW filter Sharp non BPF Fig 5 500 Hz CW filter Soft Fig 6 250 Hz CW filter Sharp The above examples depict typical filter passbands Due to the limited dynamic range of the measurement method the amplitude scale is not accurate 11 5 NR noise reduction measured as SINAD This test is intended to measure noise reduction on SSB signals close to the noise level The test signal is offset 1 kHz from the receive frequency to produce a test tone and RF input power is adjusted for a 6 dB SINAD reading 120 dBm NR is then turned on and SINAD read at 30 50 and 60 max NR settings Test conditions 10 000 MHz LSB 2 4 kHz Sharp AGC MID preamp off ATT off NR off NB off Twin PBT neutral SINAD dB
7. no evidence of AGC clamping In Fig 10 the dark blue bars are the inter pulse intervals and the light blue bars are the AGC recovery intervals Fig 10 AGC response for RF bursts at 10 dBm 14 7b Test with pulse trains Here the pulse generator is coupled to the IC 7600 RF input via the pick off port of a line sampler The sampler s main port is terminated in 50Q The IC 7600 is tuned to 10 MHz as the RF spectral distribution of the test pulse train has a strong peak in that band AGC Fast 0 1 sec is selected as before but Preamp 2 is selected The pulse rise time to 70 of peak amplitude is 10 nS Three pulse durations are used 30 50 and 100 nS In all cases pulse period is 600 mS Pulse amplitude is 16V5x e m f As in Test 7a the AGC recovers completely there is no evidence of clamping 30 100 00 EE GE S6 50 100 no clamping S8 100 100 no clamping S8 Fig 11 AGC response for pulse trains 30 nS duration 8 Noise blanker NB impulse response As the IC 7600 s noise blanker is a DSP process upstream of the AGC derivation point the NB should be very effective in suppressing impulsive RF events before they can stimulate the AGC To verify this the NB is turned on during Test 7b above NB Level is adjusted for best suppression of the test pulses At 30 nS pulse duration the S meter deflection is completely suppressed showing that the impulsive events neve
8. of the IC 7700 s NB The NB menu threshold depth and width is accessed by pressing and holding the NB key The NB works very effectively in conjunction with NR 12 AGC system The IC 7600 has dual AGC loops The primary loop uses an analog AGC detector at the output of the 2 IF amplifier 36 kHz This loop limits the IF signal power applied to the ADC input thereby preventing ADC over ranging even in the presence of extremely strong signals The digital AGC detector for the secondary loop is within the DSP algorithm Level indications from both detectors are processed in the DSP for AGC management This architecture prevents strong adjacent signals from swamping the AGC and allows full exploitation of the ADC s dynamic range The AGC menu is similar to that of the IC 756Pro3 The Slow Mid and Fast AGC settings are customizable via menu for each mode 13 Receive and transmit audio menu The IC 7600 LEVEL menu offers the same generous selection of audio configuration parameters as that of the IC 7700 TBW low and high cutoff frequencies RX and TX Bass Treble EQ RX HPF and LPF transmit compression etc Pressing and holding the COMP softkey opens a menu allowing independent selection of compression on off TBW WIDE MID NAR and compression level 14 Metering As in the IC 7700 an on screen emulation replaces the traditional moving coil meter An item in the DISP menu allows selection of a standard edgewise or bar graph meter disp
9. scale is read with 50Q and 100Q resistive loads connected in turn to ANT1 To minimize the effect of line lengths on measurement accuracy this test is run at 1 8 MHz The RF POWER setting remains unchanged when switching loads Test conditions 1 81 MHz RTTY P 10W into 50Q load Resistance 50 10 100 90 1 0 1 2 1 1009 Note that with 100Q load the SWR reading is dependent on Po 22 SSB transmit audio frequency response In this test a white noise baseband is applied to the USB port from a tone generator program running on a laptop computer The spectrum analyzer is loosely coupled to the IC 7600 RF output via the line sampler At 100W CW the line sampler is initially adjusted for a convenient 0 dBc reference Test conditions 14100 kHz USB DATA OFF MOD USB USB Level 50 default Test signal white noise WIDE MID and NAR TBW are at default values On computer adjust USB Audio Codec device volume for 45 ALC reading Using Marker on spectrum analyzer measure frequency and relative amplitude at lower passband edge Move marker down 6 dB and record frequency Move marker down a further 14 dB and record frequency again Repeat procedure for upper passband edge 6 dB 20 dB 6 dB 20 dB 505 435 2505 2560 305 205 2655 2785 80 40 2900 2993 Copyright 2009 A Farson VA7OJ AB4OJ All rights reserved April 2 2009 26
10. sidebands at 50 wpm 14 1 MHz 100W 20 ACC 1 Pin 4 analog baseband input level for 100W output A test tone is injected into ACC 1 Pin 4 and the input voltage required for 100W RF output is noted Test conditions 14100 kHz USB DATA OFF MOD ACC DATA 1 MOD ACC test tone kHz Adjust test tone level for 100W output in USB and USB D1 modes The required input levels were 56 mV rms for USB and 81 mV rms for USB D1 21 Autotuner ATU insertion loss In this test the transmitter is set for 100W output P on various bands On each band the ATU is activated and tuned and the output P gt measured and noted ATU insertion loss 10 logio P2 P Test conditions RTTY mode 3 6 14 1 and 50 1 MHz successively P 100W RF power meter and 50Q resistive load connected to ANT1 3 6 100 91 0 4 14 1 100 89 0 5 50 1 100 85 0 7 25 21a Autotuner hunting check In this test the ATU is activated and tuned at 100W output on each band in turn On each band a brief SSB transmission is made during which the tester checks aurally for ATU sounds and visually for random SWR flutter above 1 1 Test conditions 1 RTTY mode midband frequency on each band in turn Po 100W RF power meter and 50Q resistive load connected to ANT 1 2 Brief voice transmission in SSB mode No audible or visible evidence of ATU hunting was observed on any band 21b SWR scale accuracy The SWR
11. working and was displaying PSK31 and RTTY traffic and waterfalls DM780 is a component of HRD Simon and I plan to verify HRD IC 7600 inter operation more exhaustively next month 19 USB Thumb Drive I did not upload firmware to the IC 7600 but successfully saved and loaded SETTINGS and VOICE files to and from a 1 GB USB thumb drive inserted in the front panel USB socket 20 Conclusion After several days worth of cockpit time on the IC 7600 I am very favorably impressed by its solid refined construction attractive and informative display easy familiarization experience smooth operating feel impressive array of features and excellent on air performance This radio offers most of the functionality and performance of the IC 7700 in a Pro3 sized package and in a price class between the Pro3 and the IC 7700 Icom have again scored a coup with the straightforward USB computer interface 21 Acknowledgements I would like to thank Ray Novak N9JA at Icom America and Paul Veel VE7PVL and Jim Backeland VE7JMB at Icom Canada for making an IC 7600 available to me for testing and evaluation I would also like to thank Simon Brown HB9DRYV for his assistance in verifying HRD operation with the IC 7600 Adam Farson VA7OJ AB40J e mail farson shaw ca http www ab4oj com April 2 2009 Copyright 2009 A Farson VA7OJ AB40J All rights reserved Appendix 1 Performance Tests on IC 7600 S N 0201203 As performed in my home
12. 9 84 dBm Preamp 2 on S9 83 dBm Measured AGC threshold preamp OFF 93 d Bm 9a Attenuator tracking This is a quick verification of attenuator accuracy 10 In Band IMD test The purpose of the In Band IMD Test is to measure the _ATT dB Value dB 0 0 6 7 12 13 18 19 intermodulation IMD products present in the audio output of the receiver when two closely spaced signals both falling within the IF passband are applied to the RF input In this test two signals f and fz of equal amplitude and separated by 200 Hz offset are injected into the receiver input f 10000 0 and fz 10000 2 kHz The 3 order IMD products are at 9999 8 and 10000 4 kHz respectively The two test signals are combined in a passive hybrid combiner and applied to the receiver input via a step attenuator A baseband spectrum analyzer here a PC running a FFT spectral analysis program is connected to the IC 7600 s rear panel USB port 16 Test Conditions IC 7600 tuned to 9999 6 kHz 3 6 kHz USB NR off NB off Preamp off ATT off AGC MID RF input power 57 dBm composite each test signal 63 dBm Baseband spectrum analyzer reference level adjusted to place test signals at 10 dB line Fig 12 illustrates the test signals and 3 order IMD products dB eels Se Gk 8 8 amp 1 1 m n me R sy 858858 1 x PAZ AG
13. HD with single tone modulation As in Test 13 above the spectrum analyzer is loosely coupled to the IC 7600 RF output via a line sampler On the IC 7600 RF Power is adjusted for 25W resting carrier The line sampler is adjusted to set the carrier at a convenient 0 dBc reference A 1 kHz test tone is applied to the USB port from the tone generator program running on the laptop computer The spectrum analyzer records the carrier and sideband parameters Test conditions 14100 kHz AM DATA OFF MOD USB USB Level 50 default On computer adjust USB Codec device volume for 7 dBc test tone level 90 modulation Fig 17 shows the carrier and sideband levels Calculated THD 1 7 Fig 17 AM carrier and sideband parameters 21 17 Transmitter spectral purity Once again the spectrum analyzer is loosely coupled to the IC 7600 RF output via a line sampler At 100W RTTY the line sampler is initially adjusted for a convenient 0 dBc reference and the spectrum analyzer s harmonic capture utility is started Test conditions 14 1 MHz and 50 1 MHz RTTY 100W output to 50Q load Utility start and stop frequencies are configured as shown in Figs 18b and 19b Fig 18a Harmonics at 14 1 MHz 100W Fig 18b Spectral purity at 14 1 MHz 100W 22 HARMONIC MEASUREMENT RESLL TS PLUNDAMENTAL SIGNAL 53 18 HHE 18 6 din HARMONIC LEVEL d 71 0 062 53 m 1 7 99 0 m EL WEASURED LEVEL MAY BE MOISE OF LOST SIGNAL
14. IC 7600 User Evaluation amp Test Report By Adam Farson VA70J AB40J Iss 3 April 2 2009 Introduction This report describes the evaluation of IC 7600 S N 0201203 from a user perspective Appendix I presents results of an RF lab test suite performed on the radio I was able to spend a number of days with the IC 7600 in my ham shack and thus had the opportunity to exercise the radio s principal features and evaluate its on air behavior 1 Physical feel of the IC 7600 Owners of IC 756Pro series transceivers should find the IC 7600 very familiar and will immediately feel comfortable with it The front panel layout is quite similar to that of the IC 756Pro3 except that the larger TFT display now takes up the space vacated by the removal of the analog meter The learning curve will be minimal also for IC 7700 or IC 7800 owners The main tuning knob has a knurled Neoprene ring similar to that of the IC 7700 it turns very smoothly without side play The major rotary controls are identical to those of the IC 756Pro3 although the BAL NR and AF RF SQL controls are in a vertical line rather than side by side The larger screen accommodates 6 softkeys and 6 mode keys as compared to 5 on the Pro3 the new RTTY PSK key is to the right of the CW key The IC 7600 is solidly constructed and superbly finished It conveys a tight smooth and precise overall feel as did its predecessors The sheet steel case is finished in an attractive black c
15. TOTAL HARMONIC DISTORTION OF HARMONICS MEASURED Fig 19b Spectral purity at 50 1 MHz 100W 23 18 Transmitted composite noise As before the spectrum analyzer is loosely coupled to the IC 7600 RF output via the line sampler At 100W RTTY the line sampler is initially adjusted for a convenient 0 dBc reference and the spectrum analyzer s phase noise utility is started Figs 20a and 20b are the resulting composite noise plots Test conditions 14 1 MHz and 50 1 MHz RTTY 100W output to 50Q load Utility minimum maximum offset and spot frequencies configured as shown in Figs 20a and 20b Note The limitation of this measurement method is that the measured noise power is close to the spectrum analyzer s own noise floor a 186 6 Kee 116 17 da maa FREGLENCY OFFSET FROM 14 10 Mu CARRIER Fig 20b Composite noise at 50 1 MHz 100W 24 19 Spectral display of CW keying sidebands Again the spectrum analyzer is loosely coupled to the IC 7600 RF output via the line sampler At 100W CW the line sampler is initially adjusted for a convenient 0 dBc reference and a series of dits is transmitted at the highest keying speed Test conditions 14 1 MHz CW 100W output to 50Q load Equivalent keying speed 50 wpm KEY SPEED max using internal keyer Spectrum analyzer RBW is 10 Hz video averaged sweep time lt 4 sec Fig 21 shows the transmitter output 5 kHz from the carrier Fig 21 Keying
16. also AN reduced the levels of multiple tones suppressing the higher pitched tone and reducing the level of the lower pitched tone by about 20 dB b CW I also worked a station on 20m CW using a straight key QSK and semi break in There was no evidence of dit clipping With a 250 Hz CW filter Sharp BPF and NR NB on ringing was minimal with Preamp off I then set up a 250 Hz filter Soft non BPF with NR on and Preamp off There was virtually no audible ringing and the CW note was very smooth Activating Preamp 1 or 2 raised the noise level causing some ringing which was especially noticeable in the absence of signals By narrowing receive audio bandwidth the APF improved the S N of the recovered audio and yielded a slightly smoother CW note this was especially evident with APF set to Soft NAR Auto Tune pulled in CW signals to the preset pitch value effectively even at low signal levels S1 S2 c AM In a quick check of AM reception I listened to various MF and HF broadcast stations A local station on 690 kHz and a music broadcast on 6910 kHz sounded good on the IC 7600 s internal speaker but much clearer as one would expect on my SP 20 or on the headset The 9 kHz AM filter offered the best frequency response but the 6 kHz setting sounded somewhat smoother and 3 kHz cut the highs excessively The IC 7600 s Twin PBT is fully functional in this mode Mid AGC was fine under average to good s
17. conditions allow e RTTY I successfully tuned in and decoded even weak and noisy RTTY signals The familiar tuning bar display together with the FFT scope and waterfall display to the right of the encode decode text field make correct tuning very easy The squelch can be set to mute the audio in the absence of a received signal this is especially useful when using the Twin Peak Filter TPF Rie 17 Test for EMC and Baseband Levels No EMC issues of any sort Level were observed when using a headset plugged into the IC 7600 s PHONES jack or an external speaker connected to the radios EXT SP jack Tests were conducted at 1 kW on 40 20 17 15 12 and 10m and at 500W on 6m EJ I measured the RX baseband output levels at the USB port using DM780 and at ACC 1 Pin 5 AF with a true RMS DVM With a 10 000 MHz S9 10 dB test signal offset 1 kHz to yield a I kHz test tone DM780 read 76 of full scale and the level at ACC 1 Pin 5 was gt 213 mV RMS well within the 100 300 mV spec HEE 18 Interfacing with Ham Radio Deluxe HRD Simon Brown HB9DRV and I have done some preliminary work to interface his well known software suite to the IC 7600 The single USB interconnection greatly facilitated this task I installed the Icom USB drivers downloadable from the Icom Japan world wide support site and HRD on my laptop The IC 7600 showed up in the computer as USB Audio Codec Once I had set the levels correctly HRD started
18. d PBT CLR key operate in exactly the same manner as on the IC 756Pro series as does the BPF filter configuration feature for filter bandwidths of 500 Hz or less The APF TPF key selects the Audio Peak Filter APF in CW mode and the Twin Peak Filter TPF in RTTY mode The APF offers Sharp and Soft shape factors and 3 bandwidth selections When APF is selected a pop up icon is displayed allowing selection of WIDE MID or NAR BW by pressing and holding the key 7 BPF vs non BPF filters As in other Icom IF DSP radios the IC 7600 allows the user to select two additional shapes for 500 Hz or narrower filters in addition to SHARP and SOFT These are BPF steeper skirts and non BPF softer skirts To configure a BPF filter select a 500 Hz or narrower CW RTTY or SSB D filter with Twin PBT neutral To set up a non BPF filter select a filter with BW gt 500 Hz and narrow the filter to 500 Hz or less by rotating the Twin PBT controls Numerical and diagrammatic bandwidth displays and a BPF Indicator icon facilitate use of this feature Examples of BPF and non BPF filter passbands are illustrated in Figs 3 amp 4 Page 8 8 Notch Filters The tunable manual notch filter MN is inside the AGC loop and is extremely effective The MN has 3 width settings WIDE MID and NAR its stopband attenuation is at least 70 dB The manual notch suppresses an interfering carrier before it can stimulate AGC action it thus prevents swamping Th
19. d adjustment range as the IC 7700 scope The DISP menu is very similar to that of the IC 7700 allowing flexible color adjustment etc The display is backlit by white LED s Gone are the CCFL cold cathode fluorescent lamp and its DC DC converter The Notch MN and APF keys open pop ups which can be used to select notch width and APF bandwidth respectively 4 Spectrum Scope As in the IC 7700 the IC 7600 scope offers CENTER and FIX modes The CENTER mode has selectable spans from 2 5 to 250 kHz selectable sweep speeds and variable resolution bandwidth RBW in the range 100 Hz to 4 kHz The optimum RBW value is automatically selected for each span and sweep speed setting At 2 5 kHz span and SLOW sweep speed the minimum RBW is selected This allows a clear display of IMD products and AM sidebands for example At the narrower RBW settings the grass level in the absence of signals is at or near baseline Weak signal spikes are thus clearly visible The IC 7600 spectrum scope also provides a very useful spectral content display of the transmitted signal at the 2 5 kHz span and SLOW sweep settings One can use this display as an aid when setting up the transmit audio Scope during TX ON in Scope Set menu Pressing and holding the MAIN SUB key opens the mini scope display as in the IC 756Pro3 In FIX mode the spectrum scope presents a sweep of a defined range typically an amateur band with upper and lower limits configurable v
20. e RF input power is increased until the receiver noise floor increases by 3 dB as measured at the audio output Reciprocal mixing noise expressed as a figure of merit is the difference between this RF input power and measured MDS The test is run with preamp off The higher the value the better Test conditions SSB mode 2 4 kHz filter preamp off ATT off NR off NB off Reciprocal mixing in dB input power MDS both in dBm Offset kHz 3 6 MHz TSB tat Mie USB 3 IF filter shape factor 6 60 dB This is the ratio of the 60 dB bandwidth to the 6 dB bandwidth which is a figure of merit for the filter s adjacent channel s rejection The lower the shape factor the tighter the filter In this test an approximate method is used An RF test signal is applied at a power level approx 60 dB above the level where the S meter just drops from S1 to SO The bandwidths at 6 and 60 dB relative to the input power are determined by tuning the signal generator across the passband and observing the S meter Reciprocal mixing noise limits the level range to 60 dB or less Test conditions 10 000 MHz SSB CW modes preamp off AGC MID ATT off NR off NB off __ Filter _ Sharp Soft 2 4kHz SSB 1 46 1 63 500 Hz CW 1 38 1 77 250 Hz CW 1 44 1 93 4 SSB filter roll off An RF test signal is applied at a level 6 dB below AGC threshold with AGC off The signal is offset 1 kHz
21. e auto notch filter AN is post AGC It suppresses single and multiple tones but strong undesired signals can still cause AGC action and swamp the receiver MN and AN are mutually exclusive and ANF is inoperative in CW mode The NOTCH key toggles OFF AN MN When MN is selected a pop up icon is displayed allowing selection of WIDE MID or NAR narrow notch by pressing and holding the key Operation of the NOTCH key is identical to that in the IC 7700 9 Auto Tune As in the IC 7700 this feature is a form of AFC which at the push of a button correctly tunes CW signals to the pitch set via the CW PITCH control and AM signals to carrier at passband center Auto Tune is effective even on fairly weak signals 10 NR noise reduction The DSP NR functionality is comparable to that of the IC 7700 and works very well In SSB mode the maximum noise reduction occurs at an NR control setting of 60 As NR level is increased there is a slight loss of highs in the received audio this is as expected The measured SINAD increase in SSB mode was about 10 dB 11 NB noise blanker The IF level DSP based noise blanker is arguably one of the IC 7600 s strongest features I found it to be extremely effective in suppressing fast rising impulsive RF events before they can stimulate AGC action within the DSP algorithm The NB completely blanks noise impulses which would otherwise cause AGC clamping I found its performance comparable to that
22. ia menu The current receive and transmit frequencies are shown as movable marker lines giving the effect of a slide rule dial 5 USB interfaces The IC 7600 is equipped with a front panel USB A port and a rear panel USB B port The A port accepts a thumb drive for storage and loading of configuration settings RTTY PSK31 traffic and sound wav files The radio can be directly connected via the B port to a laptop or other PC via a standard USB A B cable This is without doubt one of the IC 7600 s strongest features The USB port transports not only CI V data but also TX and RX PCM baseband between the IC 7600 and the computer As a result the USB cable is the only radio PC connection required Gone forever is the mess of cables level converters and interface boxes I believe that this feature will be standard on all future Icom HF radios 6 Filter selections and Twin PBT As do the other Icom DSP transceivers the IC 7600 offers fully configurable RX IF selectivity filters for all modes Three default filter selections are available for each mode with continuously variable bandwidth via the FILTER menu In addition there are selectable Sharp and Soft shape factors for SSB and CW The IC 7600 is fitted with 15 6 and 3 kHz MCF roofing filters at the 64 455 MHz 1 IF The filter menu allows association of any one of the 3 roofing filters with each of the 3 IF filter selections The Twin PBT controls an
23. ic supplied with the IC 7600 It was noted that higher COMP settings caused slight distortion on voice peaks when using the HM 36 Note that the area of the rear panel behind the PA Unit became quite warm after a few hours rag chew SSB operation at 65 70W PEP output The following are the settings I used in the SSB trials Transmit Audio Settings HC 5 20m S9 50 WIDE OFF 0 2 HM 36 20m S9 60 WIDE 1 5dB 2 4 HC 5 17m 5 QSB 50 MID 6 dB 2 3 The DSP based noise blanker is superb It does not distort the signal at all and can be left on at all times it is just as good as the IC 7700 blanker At one point the desired signal was severely degraded by locally generated impulse noise With the blanker off the noise clamped the AGC and deflected the S meter to S9 10 dB With the blanker on the noise was almost completely suppressed and the S meter read approx S1 The signal could now be clearly heard As discussed in Section 10 above I found the NR very effective on SSB Even at 60 NR did not attenuate highs excessively NR is very effective in conjunction with NB Preamps 1 and 2 10 and 16 dB gain respectively brought weak stations up to very comfortable copy without S N degradation The SSB filters and Twin PBT were excellent as we have come to expect from other Icom DSP radios MN and AN were extremely helpful I was able to notch out single tones with MN
24. ignal conditions but I found Fast AGC quite useful in dealing with rapid selective fading NR was quite effective in improving the S N ratio of weak AM signals Some band noise hiss was evident on AM with NR off but NR effectively eliminated it The NR did not cause distortion even at it maximum setting 60 Above 60 the NR control has no further effect Note that the AM bass and treble EQ settings were both 0 dB with HPF off Some distortion was observed on AM at NB gt 50 this became unacceptable at NB gt 75 I found that NB NR caused less distortion than NB alone AN was effective in suppressing unwanted tones and heterodynes but MN caused some distortion when tuned across the signal The reason for this is that MN suppresses the carrier in a manner similar to selective fading Auto Tune also worked very well in AM mode pulling in AM signals within 1 sec Note also that unlike the IC 756Pro3 the IC 7600 does not insert a pad in the RF IF signal path for f lt 1 6 kHz d PSK31 is simplicity itself with the IC 7600 s PSK mode The vector diagram FFT scope AFC menu and waterfall display to the right of the encode decode text field greatly facilitate correct tuning With a keyboard plugged into the front panel USB port the IC 7600 becomes a self contained HF 6m PSK31 and RTTY terminal The IC 7600 decoded weak S1 S2 20m PSK31 signals reliably with a few errors due to QSB I plan to conduct a PSK31 QSO when band
25. lay Pressing the METER softkey toggles among Vp PA drain supply voltage Ip PA drain current Po SWR ALC and COMP Pressing and holding the METER softkey displays a multi function bar graph meter group including Vp and a relative TEMP internal temperature scale A rear panel METER jack allows connection of an external meter The meter parameters are configurable via the ACC menu 15 Dual Watch This feature operates exactly as in the IC 756Pro3 With the BAL control fully clockwise the spectrum scope grass level rises 6 dB as the PIN diode balance attenuator leaves the A 1 mixer IF output unterminated at maximum attenuation This increases the IF signal power at the scope sampling point by 6 dB 16 Brief on air report Prior to starting the test suite I installed the IC 7600 in my shack and connected it to my solid state 1 kW amplifier and multi band vertical antenna The interface was straightforward RF drive PTT ALC and carrier request for amplifier auto tuning Once I had set up the ALC for I kW output I was 100 QRV a SSB I made several 20m and 17m SSB QSO s with friends who are familiar with my voice and the sound of my signal Distant stations reported that the audio quality of my transmissions was clean and natural when using the Heil ProSet Plus headset and GM 5 hand mic with the HC 5 element Two stations I worked on 20m SSB assisted me in optimizing transmit audio settings for the HM 36 hand m
26. o peak vertical deflection of 6 divisions Test conditions USB mode HM 36 mic connected Mic Gain 45 COMP OFF ON MID Comp set at 3 6 dB compression on voice peaks supply voltage 13 8V SSB TX Bass Treble set at 0 dB default Speak loudly into the microphone for full scale ALC reading Figs 13 amp 14 show the envelope for 100W PEP without and with compression respectively Fig 13 100W PEP speech envelope no compression Fig 14 100W PEP speech envelope 6 dB compression 19 15 Transmitter 2 tone IMD test In this test a 2 tone test signal is applied to the USB port from a tone generator program running on a laptop computer A spectrum analyzer is loosely coupled to the IC 7600 RF output via a line sampler At 100W CW the line sampler is initially adjusted for a convenient 0 dBc reference Test conditions DC supply 13 8V measured at DC power socket 14100 kHz USB DATA OFF MOD USB USB Level 50 default Test tones 700 and 1700 Hz at equal amplitudes On computer adjust USB Audio Codec device volume for 100W PEP each tone at 6 dBc Figs 15 and 16 show the two test tones and the associated IMD products Fig 15 Spectral display of 2 tone IMD at 14 1 MHz 100W PEP Fig 16 Spectral display of 2 tone IMD at 50 1 MHz 100W PEP 20 F IMD Products drais a 0 oz 2 tone PEP IMD3 31 IMD5 5 order IMD7 7 order IMD9 9 order 16 AM sidebands and T
27. r reach the AGC derivation point At NB Level 80 Depth 8 Width 50 slight ticks are heard At Width 100 the pulse ticks are almost inaudible a very faint chuff sound is heard for each pulse Signals and or band noise would mask this completely Next NR is activated With NR at 50 and NB on the ticks are completely inaudible default values 15 S0 S1 93 91 9 S meter tracking amp AGC threshold This is a quick check of S meter signal level tracking Test conditions 2 4 kHz USB Preamp off ATT off AGC MID A 14 100 MHz test signal at MDS is applied to the RF input The signal power is increased and the level corresponding to each S meter reading is noted S9 readings are taken with Preamp off Preamp 1 and Preamp 2 in turn To measure AGC threshold the test signal is offset 1 kHz to produce a test tone and the input level turned down to MDS The IC 7600 AF Gain control is adjusted for 6 dBr test tone level The input signal power is then increased until test tone level no longer increases The test is then repeated with AGC OFF The actual AGC threshold knee is the point at which the AGC OFF test tone level first exceeds that for AGC ON normal S2 S3 S4 S5 S6 S7 S8 S9 S10 SH20 9430 9440 SH50 SH60 38 36 34 81 78 75 B 70 59 49 39 29 17 7 Preamp 1 on S
28. rinkle coating and fitted with a handle on the left side The case retaining screws are located in recesses in the case covers The front panel has a smooth matte surface not textured as in the IC 756Pro3 The diecast compartmented chassis is very similar to that of the Pro3 but has an attractive new feature all jacks and connectors are individually marked The 7600 is fitted with the new 4 pin DC power socket Switchable RX OUT and RX IN jacks are fitted allowing the connection of an external preamplifier RF filter or preselector or a receiving antenna Both the case and the rear panel are well ventilated The front case feet are solid and extensible allowing the front of the IC 7600 to be angled upwards The 7 softkeys at the left edge of the screen are now black and almost flush with the panel A triangular index mark is molded into each key I would have liked to see these marks filled in white for easier operation in low light 2 Control knob key functions and menus Apart from minor differences in placement the IC 7600 s control knobs will be very familiar to 756Pro series users The menus are more akin to those in the IC 7700 as the IC 7600 s feature set is very similar to that of the 7700 but with Dual Watch added I found the set up process fairly intuitive after a consulting the relevant user manual sections in cases of doubt e g the COMP menu As in the IC 7700 the SPAN PREAMP and ATT selections can be returned to defa
29. ult by pressing and holding their respective softkeys The filter selection and adjustment procedure is similar to that on other Icom DSP radios Press and hold the FILTER key for 1 sec to adjust the filter bandwidth select CW SSB Sharp Soft shape factors and match the desired roofing filter to each IF filter and mode All IF filters are continuously adjustable Being a current IC 7700 owner and former 756Pro series owner I found that the IC 7600 s controls and menus fell readily to hand A user familiar with a radio such as the IC 756Pro3 or IC 7700 should find the IC 7600 s learning curve minimal The IC 7600 s default settings are very usable allowing the radio to be placed in service with minimal initial set up Due to space constraints compression level is now set via a menu Pressing and holding the COMP key displays the COMP adjustment menu a peak reading COMP meter scale and a TBW selection menu WIDE MID NAR The IC 7600 also has a Drive Gain adjustment menu absent from the IC 756Pro series this is accessible via the LEVEL menu The 50 default value for Drive Gain places the ALC reading just below 50 as recommended in the user manual 3 LCD display screen The 5 8 inch diagonal QVGA TFT color screen has 400 X 240 pixel resolution The display is very bright and crisp and presents all radio parameters The display layout is very similar to that of the IC 7700 The DSP based spectrum scope has the same capabilities an
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