IC-7200 review
Contents
1. 10 Transmit audio parameters The IC 7200 has only two transmit audio menu items Mic Gain and compression level The DSP IF level compressor is similar to that provided on other Icom DSP radios It works very smoothly and does not distort at the default compression level value of 5 approx 6 dB compression The IC 7200 supports emission designator 2K 8J3E to ensure FCC compliance on 60m Thus no transmit bandwidth or equalization menus are provided The corresponding AM designator is 5K6A3E double sideband The RTTY mode supports F1B FSK TX only and F2B AFSK Note that the IC 7200 is not fitted with a transmitter audio monitor 11 Metering Three selectable transmit meter scales are provided P RF output SWR and ALC Only one of these is displayed In receive the on screen bar graph indicator is always the S meter 12 Interfacing with Ham Radio Deluxe HRD Simon Brown HB9DRV and I worked together over a period of several evenings to interface his well known software suite to the IC 7200 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 7200 showed up in the computer as USB Audio Codec Once I had set the levels correctly HRD started working and was displaying PSK31 and RTTY traffic and waterfalls A level problem was discovered in the course of this task Simon reported that the PC2. At 30 nS pulse duration the S meter deflection is completely suppressed showing that the impulsive events never reach the AGC derivation point Faint ticks are audible in the speaker as NB Level is varied the ticks are quieter at 100 than at 0 Next NR is activated With NR and NB on the ticks are inaudible 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 normal 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 7200 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 SO S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S20 S940 SOHO S9450 SH60 93 91 89 36 34 81 78 76 3 710 51 40 32 25 16 Preamp on s9 84 dBm ATTO S9 50 dBm 12 B Transmitter Tests 10 CW Power Output In
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4. to 3 dBr is 200 nS Pulse period is 600 mS At 10 dBm S meter peaks to S9 20 dB The result for 20 dBm is similar The AGC recovers completely in 200 mS There is no evidence of AGC clamping In Figure 9 the blue bars are the inter pulse intervals and the black bars are the AGC recovery intervals Figure 9 AGC response for RF bursts at 10 dBm 7b Test with pulse trains Here the pulse generator is coupled to the IC 7200 RF input via the pick off port of a line sampler The sampler s main port is terminated in 50Q The IC 7200 is tuned to 2 MHz as the RF spectral distribution of the test pulse train has a strong peak in that band AGC Fast is selected as before but Preamp is on The pulse rise time to 70 of peak amplitude is 10 nS Three pulse durations are used 30 50 and 10 nS In all cases pulse period is 600 mS Pulse amplitude is 16V pk e m f As in Test 7a the AGC recovers completely there is no evidence of clamping 100 no clamping 50 100 no clamping 100 100 no clamping 11 Figure 10 AGC response for pulse trains 8 Noise blanker NB impulse response As the IC 7200 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
5. 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 On the IC 7200 this must be done by ear or by means of spectral analysis software in the connected PC Examples are illustrated in Figures 3 amp 4 Page 8 7 Notch Filters The tunable manual notch filter MNF is inside the AGC loop and is very effective The MNF has 3 width settings Wide Mid and Narrow its stopband attenuation is at least 70 dB The manual notch suppresses an interfering carrier before it can stimulate AGC action thus preventing swamping The auto notch filter ANF is post AGC It suppresses single and multiple tones but strong undesired signals can still cause AGC action and swamp the receiver MNF and ANF are mutually exclusive and ANF is inoperative in CW mode 8 NR noise reduction The DSP NR functionality works very well In SSB mode the maximum noise reduction occurs at a level setting of 10 max 15 As NR level is increased there is some loss of highs in the received audio this is as expected The measured SINAD increase in SSB mode was about 6 dB 9 NB noise blanker I found the DSP NB somewhat more effective than the IC 756Pro III s analog NB It will strongly attenuate fast rising noise pulses but is somewhat less effective on power line hash NB works best in conjunction with NR
6. one of the IC 7200 s strongest features The USB port transports not only CI V data but also TX and RX PCM baseband between the IC 7200 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 This is a feature which I would really like to see on all future Icom HF radios 5 Filter selections and Twin PBT As do the other Icom DSP transceivers the IC 7200 offers fully configurable RX IF selectivity filters for all modes Default Wide Mid and Narrow filter selections are available for all modes with continuously variable bandwidth via menu In addition there are selectable Sharp and Soft shape factors for SSB and CW As mentioned in Section 1 the Twin PBT controls have a center detent which facilitates setting Twin PBT to the neutral position nominal bandwidth no passband shift The IC 7200 Twin PBT feature operates similarly to that of all other Icom DSP radios except that there is no BPF icon or visual indication of passband modification on the LCD This places the user at a slight disadvantage when configuring a non BPF filter 6 BPF vs non BPF filters As in the IC 756Pro series and the IC 746Pro the IC 7200 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
7. test tone level 100W PEP Figure 13 shows the two test tones and the associated IMD products Figure 13 Spectral display of 2 tone IMD at 100W PEP 2 tone IMD Products at 100W PEP IMD Products Relative level 0 dBc 2 tone PEP IMD3 3 order 33 dBc IMD5 5 order 37 dBc IMD7 7 order 50 dBc IMD9 9 order 59 dBc 14 13 AM spectrum and THD with single tone modulation As in Test 12 above the spectrum analyzer is loosely coupled to the IC 7200 RF output via a line sampler On the IC 7200 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 Test Conditions 14100 kHz AM DATA on Mod u USB Level 100 On computer adjust USB Codec device volume for 7 dBc test tone level 90 modulation Figure 14 shows the carrier and sidebands Note the additional sidebands due to harmonic distortion at the high modulation level The 2 and 3 harmonics are at 32 and 37 dBc respectively corresponding to 2 8 THD Figure 14 AM carrier and sidebands 0a V Carrier 90 Mod a 33 dBc 3 36 dBc ae 47 dBc 5h 58 dBc 15 14 Power output tests December 3 2008 Several IC 7200 owners who operate their radios in mobile portable configurations or on sailboats have express
8. 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 ower Setting Meter er Output W 75 70 100 100 100 130 11 SSB Peak Envelope Power PEP Here an oscilloscope is loosely coupled to the IC 7200 RF output via a line sampler At 100W CW the line sampler is adjusted for a peak to peak vertical deflection of 6 divisions Test conditions USB mode Mic Gain 50 Comp Level 10 supply voltage 13 8V Speak loudly into the microphone for full scale ALC reading Figures 11 amp 12 show the envelope for 100W PEP without and with compression respectively Note that here COMP LVL 10 to show the effect of compression In practice COMP LVL should be 5 or lower Figure 11 100W PEP speech envelope no compression Figure 12 100W PEP speech envelope with compression 13 12 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 7200 RF output via a line sampler At 100W CW the line sampler is adjusted for a convenient 0 dBc reference here 10 dB below reference level Test Conditions DC supply 13 8V measured at DC power socket 14100 kHz USB D DATA on D Mod u USB Level 100 Test tones 700 and 1700 Hz at equal amplitudes On computer adjust USB Codec device volume for 6 dBc
9. 1 IC 7200 User Evaluation amp Test Report By Adam Farson VA70J AB40J Iss 3 December 3 2008 Supersedes Iss 2 November 28 2008 Introduction This report describes the evaluation of IC 7200 S N 0201013 from a user perspective as well as the results of several RF lab tests performed on the radio I was able to spend a number of days with the IC 7200 in my ham shack and thus had the opportunity to exercise the radio s principal features and evaluate its on air behavior Appendix 1 is the detailed test report 1 Physical feel of the IC 7200 The IC 7200 conveys the solidity typical of a military tactical mobile radio set I found the overall feel of the main tuning knob and other controls very smooth and pleasant The rugged construction of the case and front panel with the positive tactile feel of the Neoprene push keys adds to this impression of solidity The main tuning knob with its chunky Neoprene grip feels very smooth and has less than 0 5 mm side play The other rotary controls some of which are detented also have a positive feel The large concentric Twin PBT knobs are very comfortable to use although the IC 7200 lacks the PBT CLR key found on other Icom DSP radios the center detent facilitates setting Twin PBT to the neutral position The radio is solidly constructed and superbly finished It conveys a smooth precise overall feel The rear bumper protects the rear panel connectors and heat dissipator fins an
10. 2 and USB Codec Output IC 7200 S N 0201013 Test date 9 October 2008 In the course of Ham Radio Deluxe debugging it was determined that the PCM level arriving at the Digital Master 780 DM780 Monitor was very low even on strong PSK31 signals The program indicated that the PCM level arriving at the soundcard via the USB line was only 4 of the maximum possible value This can be seen in Figure 15 where the percentage level shown in the DM780 Monitor window is only 4 to 5 of maximum This low level greatly reduces the dynamic range of the PSK31 RTTY decoder in HRD Figure 15 DM780 Monitor for IC 7200 USB Output To investigate further I looked at the block diagram of the IC 7200 Page 16 is an annotated partial block diagram showing the area of interest D A converter IC1292 feeds receiver baseband to the AAFO line which in turn drives ACC Pin 12 AF OUT and USB Codec IC3202 The PCM baseband from the USB Codec is sent in digital form to the PC I set up a single tone test as follows Tune the IC 7200 to 14399 kHz USB D Data ON apply an RF signal at 14100 kHz and 70 dBm S9 to the antenna socket Measure the RX baseband 1 kHz test tone level at ACC Pin 12 with a high impedance RMS AC voltmeter The measured voltage at Pin 12 is 30 to 32 mV Per the user manual the spec is 100 to 300 mV I repeated the test on my IC 756Pro3 and IC 703 and the corresponding baseband levels at ACC1 Pin 4 AF Out were 320 mV and 100 mV resp
11. M baseband level at the input to HRD was 20 to 30 dB below the expected value A single tone test on the radio then revealed that the analog baseband level at the line audio output ACC socket Pin 12 was only 30 mV the specification calls for 100 to 300 mV As the line audio output drives the USB audio codec directly this explained the low PCM level which Simon reported This issue has been reported to Icom Refer to Appendix 2 A 13 Brief on air report After completing the test suite I moved the IC 7200 to 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 autotuning Once I had set up the ALC for 1 kW output I was off and running On tuning around 20m SSB I noted that the receive audio sounded clear and crisp on the IC 7200 s internal speaker and excellent on my SP 20 The NB was quite effective against my local power line noise but did not eliminate it completely as does the NB on my IC 7700 The NR was very effective and compared favorably with that of the IC 756Pro3 The preamp 10 dB gain brought weak KL7 stations up to very comfortable copy without S N degradation I did not have the opportunity to operate the radio under very strong signal conditions The SSB filters were excellent as we have come to expect from other Icom DSP radios The MNF and ANF were extremely helpful I was able t
12. RIT is active RIT icon displayed Again a quick read of the relevant chapter in the user manual was most helpful 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 All filters are continuously adjustable The CW Pitch control is a QUICK SET menu item rather than a separate control I found it via the user manual Pressing and holding the Preamp key inserts a 20 dB attenuator in the RF signal path in place of the preamp The radio s controls and menus were easy to use once I grew accustomed to them This is certainly a very good way of saving front panel space without hurting the radio s ergonomics A user familiar with a radio such as the IC 756Pro3 or IC 7700 should find the IC 7200 s learning curve minimal 3 LCD display Although the IC 7200 s monochrome LCD display is fairly small 64 X24 mm I found it sharp highly legible and sufficiently contrasty for comfortable viewing in bright room light or outdoors There are 3 backlight settings HI LO and off HI is the default Filter selections and feature activation are displayed via on screen icons Some of these are quite small but I found them easily readable 4 USB PC interface The IC 7200 is equipped with a rear panel USB B port Thus the radio can be directly connected to a laptop or other PC via a standard USB A B cable This is without doubt
13. ada for making an IC 7200 available to me for testing and evaluation I would also like to thank Simon Brown HB9DRYV for his enthusiasm and help in interfacing HRD to the IC 7200 Adam Farson VA7OJ AB40J e mail farson shaw ca http www ab4oj com October 11 2008 Copyright 2008 A Farson VA7OJ AB40OJ All rights reserved Appendix 1 Some Performance Tests As performed in my home RF lab October 6 11 2008 Rev 2 November 28 2008 Tests 12 amp 13 re run with HP 8563E spectrum analyzer Rev 3 Test 14 Power output tests added IC 7200 S N 0201013 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 141MH Hz_ 501MHz2__ Preamp SSB24kHz CW50 Hz SSB24kHz CW50 H SSB 24kH CW50 Hz off 124 130 124 129 131 134 on 136 5 140 136 142 139 145 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 2 4 kHz filter Levels in dBm Preamp 0 9 MHz 3 9 MHz 14 1 MHz off 97 107 107 on 107 117 115 2 Reciprocal Mixi
14. ator 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 normal ATT off NR off NB off __Filter___ Sharp Soft 24kHzSSB 1 2 1 55 500 Hz CW 1 26 2 17 250HzCW 1 4 2 56 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 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 preamp off AGC off ATT off NR off NB off Input signal level 101 dBm 6 dB below measured 95 dBm AGC threshold Roll off in dB Offset Hz Sharp Soft 250 5 300 3 400 1 5 9 500 ee 750 o 0 2000 0 5 0 7 2500 15 3 Figure 1 2 4 kHz SSB filter Sharp 3 8 Inlmbimbimbimhimbimbimbnhmhnhnlhn 1 1 w a WO 126 130 Figure 3 500 Hz CW filter Sharp BPF i 1 m 3 No o o Inlimbmbnhimhn 1 en pa 80 4 60 6 60 8 1 60 Figure 4 500 Hz CW filter Sharp non BPF 80 2 80 4 60 6 Figure 5 500 Hz CW filter Soft The above examples depict typical filter passbands Due to the limited dynamic range of the measurement method the amp
15. d the optional front handles if fitted will protect the front panel and its controls from accidental damage Installation of these handles is strongly recommended 2 Multiple key functions and menus Most of the front panel keys have secondary functions which are accessed by pressing and holding the key for 1 sec The digit entry function of the numerical keys is actually secondary and is entered by pressing the F INP key The yellow numerical digits are a clue to this as the F INP marking is yellow The secondary BAND band selection function of the F INP key is marked in white in keeping with the band markings on the numerical keys band selection is their tertiary function All this may sound more confusing than it actually is I found the process fairly intuitive after a quick read of the relevant user manual sections The SET menu familiar to users of other Icom DSP radios has two levels accessible by pressing and holding the M CH RIT key Press amp hold once to enter the QUICK SET menu transmit power output MIC Gain etc Press amp hold again to enter the in depth SET menu This menu is similar to SET OTHERS on other Icom DSP radios The M CH RIT key also serves as an EXIT key Similarly M CL restores a selected parameter to its default value I found RIT activation a bit tricky To change the M CH RIT control to RIT the RIT key must first be pressed to activate RIT The M CH RIT knob will switch to RIT automatically when
16. ectively I do not think there is an AAFO level adjustment unless there is one in the alignment menu Not having a service manual I do not know whether this is the case I suspect that a firmware change may be required B Headphone EMC issue An EMC problem was observed when using a headset plugged into the IC 7200 s PHONES jack Distorted RF feedback was heard when transmitting SSB it was quite severe at 100W and much worse at 1 kW This problem was observed on 40 20 and 17m only and disappeared when a dummy load was substituted for the antenna feedline This issue may have been local to my shack as Icom were unable to duplicate it Copyright 2008 A Farson VA7OJ AB4OJ All rights reserved December 3 2008 17 1c1091 i 3IF i l AF CH ZN pl a ZN p Y CO ZN u Y G Coo ZK LA4425A IC1081 TS462 T5462 AS zemer J 1C1661 AF AK4620B CODEC MUTE TC7WS3F Ic1551 9 ADSP B SRA D IC1601 IC1621 IC1031 128KB LY61L6416 ue j 10103 MIC TS462 TS462 A Ea ATO 30 mV FEA AT26DF081A Q EREN E ZS TK68112AMF rci681 Z SN74LVC245A M8 LEVEL 3 3V conv KI BA033 EXT SP Fig 16 Partial block diagram showing AAFO levels REFV JACK X2011 CR 770B 32 0MHz REMOTE JACK UCK i E 103201 1C3202 PCM is 20 dB low XZ us82502 PCM2901 IC3206 IC3207 TK68133AMF nev CR 871 3 3 gt REG USB UPWS IC3203 BRIDGE _ FOR USB 3 3V CP2102
17. ed interest in the transmitter output as a function of battery voltage and also in the DC input current at reduced RF power output The following tests should address these concerns Test Conditions 14 100 MHz RTTY mode for all tests except 14c 12V TX IMD USB D 14a RF power output P vs DC input current I with supply voltage Vin 13 8V as measured at DC input socket In this test Pois initially set at 100W via menu then reduced as per the table I is recorded for each P value Vin V In A Po W 13 8 20 100 18 75 16 50 15 235 10 20 9 10 8 5 e The IC 7200 s efficiency deteriorates markedly at reduced Po 14b P vs Vin as measured at DC input socket In this test Vin is initially set at 13 8V then reduced as per the table Po is recorded for each Vin value 13 8 100 13 0 100 12 5 100 12 0 95 11 5 80 11 0 67 14c Transmitted 2 tone IMD Products at Vin 12V Po 100W PEP The test procedure here is the same as for Test 12 except that Vin 12V Products at Vin 12V P 100W PEP IMD Products Relative level 0 dBc 2 tone PEP IMD3 3 order 36 dBc IMD5 5 order 35 dBc IMD7 7 order 45 dBc IMD9 9 order 59 dBc e Note that IMD5 is worse than IMD3 at reduced Vin 16 Appendix 2 Issues encountered during review and testing A Low Baseband Output ACC Pin 1
18. fault Normal AGC setting was fine under average to good signal conditions but I found the Fast setting AGC F quite useful in dealing with rapid selective fading I found that the NR was quite effective in improving the S N ratio of weak AM signals but a setting above 6 cut the highs severely The NB caused noticeable distortion on modulation peaks and caused unacceptable pumping at settings above 80 The ANF is effective in suppressing unwanted tones and heterodynes but MNF causes distortion when tuned across the signal The reason for this is that MNF suppresses the carrier in a manner similar to selective fading An EMC issue was observed when using a headset plugged into the IC 7200 s PHONES jack Distorted RF feedback was heard when transmitting SSB it was quite severe at 100W and much worse at 1 kW This problem was observed on 40 20 and 17m only and disappeared when a dummy load was substituted for the antenna feedline Refer to Appendix 2 B 14 Conclusion After several days worth of cockpit time on the IC 7200 I am very favorably impressed by its solid refined construction smooth operating feel impressive array of features and excellent on air performance This is a lot of radio in a very compact package And Icom have truly scored a coup with the straightforward USB computer interface 15 Acknowledgements I would like to thank Ray Novak N9JA at Icom America and Paul Veel VE7PVL at Icom Can
19. litude scale is not accurate 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 121 dBm NR is then turned on and SINAD read at 30 and 50 max NR settings Test conditions 10 000 MHz LSB 2 4 kHz Sharp AGC normal preamp off ATT off NR off NB off Twin PBT neutral NR Level SINAD dB 0 6 5 9 6 10 8 to 9 12 max This shows an S N improvement of 12 dB with NR at maximum for an SSB signal roughly 6 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 normal preamp on ATT 0 dB NR off NB off MNF on Twin PBT neutral Results MNF nulls out signal completely Measured MDS was 142 dBm per Test 1 Thus stopband attenuati
20. ng 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 The 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 noise in dB Offset kHz 3 6 MHz LSB 14 1 MHz USB 2 78 76 3 83 79 5 94 5 94 10 98 5 98 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 S0 The bandwidths at 6 and 60 dB relative to the input power are determined by tuning the signal gener
21. o notch out single tones with the MNF the ANF reduced the levels of multiple tones suppressing the higher pitched tone and reducing the level of the lower pitched tone by about 20 dB Two stations I worked on 20m SSB both reported that the transmit audio with the stock HM 36 hand microphone was a little on the mellow side and lacking in highs When I substituted my Heil GM 5 for the HM 36 one of these stations complimented me on the audio quality I also worked a station on 40m CW using a straight key and semi break in I did not check for dit clipping Slight filter ringing was evident when using the CW M 500 Hz and CW N 250 Hz filters with the Sharp shape factor preamp on and fast AGC There is noticeably less ringing if the Soft shape factor is selected Ringing can be reduced even further by selecting the CW W 1 2 kHz filter and narrowing it with Twin PBT non BPF 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 13690 kHz sounded good on the IC 7200 s internal speaker but much clearer as one would expect on my SP 20 The AM Wide filter 8 kHz yielded the best frequency response but Mid 6 kHz sounded somewhat smoother and Narrow 3 kHz cut the highs excessively Unlike other Icom DSP radios in which Twin PBT becomes IF Shift on AM the IC 7200 s Twin PBT is fully functional in this mode The de
22. on 72 dB 142 70 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 91 Hz Mid 48 Hz Narrow 30 Hz Figure 6 Manual Notch Filter W Figure 7 Manual Notch Filter M I oO 116 1 m w 1 b 5 Inbimibmlonbimbonlnhimhanlhl Figure 8 Manual Notch Filter N 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 10 7 AGC impulse response The purpose of this test is to determine the IC 7200 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 2 000 MHz for 7b 2 4 kHz SSB filter Sharp NR off NB off Preamp off for 7a on for 7b AGC Fast 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 10 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
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