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Icom IC-746 Faq

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IC-746 FAQ

Icom IC-746 FAQ

Frequently Asked Questions
About the
Icom IC-746 HF/VHF Transceiver
Coordinator
Dana Hoggatt
KB9SSS
kb9sss@arrl.net
Copyright (c) 2001,2002,2003 by Dana Hoggatt, all rights reserved.
Page 1 of 113
2003-02-08

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Summary of Contents for Icom IC-746

  • Page 1: Icom Ic-746 Faq

    IC-746 FAQ Icom IC-746 FAQ Frequently Asked Questions About the Icom IC-746 HF/VHF Transceiver Coordinator Dana Hoggatt KB9SSS kb9sss@arrl.net Copyright (c) 2001,2002,2003 by Dana Hoggatt, all rights reserved. Page 1 of 113 2003-02-08...

  • Page 2: Recent Changes

    Added Q/A on zero-beating CW signals 2003.02.05 Added info on annotated copy of IC-746 Instruction Manual 2003.02.05 Added info on an Italian copy of the IC-746 Instruction Manual 2003.02.04 Added another SEND amp interface 2003.02.04 Added another microphone pre-amp circuit 2003.02.04...

  • Page 3: Table Of Contents

    Should I buy an IC-746? ..................12 What are the IC-746's features?................ 12 How does the IC-746 stand up to the ______ ? ..........12 Where can I buy/sell a used IC-746?..............13 How much is a used IC-746 worth? ..............13 Is there a dedicated HF net for the IC-746? .............
  • Page 4 3.3.1 What is the best microphone to use with the IC-746? ........37 3.3.2 Can I hook up a different microphone directly to the IC-746? ...... 37 3.3.3 Can I use a Heil microphone with the IC-746? ..........38 3.3.4 How do I adjust the IC-746 for a Heil headset?..........
  • Page 5 What cables do I need?..................59 What are CT-17, OPC-478, OPC-662 all about? ..........59 Do I need a special cable to connect a CT-17 to an IC-746? ......61 What is the control protocol for the IC-746? ........... 61 What is CI-V?......................
  • Page 6 How low can the IC-746 supply voltage be?............. 69 The backlight in my LCD has stopped working. What's wrong? ....70 Is there some way to get the Icom-746 to generate DTMF tones?....73 Why don't my "band edge beeps" match the US amateur bands?....74 6.10...
  • Page 7 How does one improve the fidelity of a received signal?......... 94 8.12 How does one improve transmission fidelity? ..........95 8.13 Can the IC-746 transmit at less than 5 watts? ..........95 8.14 How do I turn on both HF pre-amps at the same time?........95 8.15 How do I adjust the 746 for best AM performance? ........
  • Page 8 IC-746 FAQ Page:42 Incorrect Page Reference ................. 100 Page:46 No ALC adjustment for either AM or FM ............. 100 Page:46 Speech compressor.................... 100 Page:53 Enter numbers via keypad, not tuning dial ............ 101 Page:56 Incorrect Page References................101 Page:68 Unclear Voltage Specification................101 Page:70 Overoptimistic SWR Specification..............

  • Page 9: Administrivia

    Welcome to the IC-746 FAQ. Short Answer FAQ stands for "Frequently Asked Questions". It tries to cover common questions, problems, and issues associated with Icom's IC-746 HF/VHF amateur radio transceiver. The master copy is kept at: http://groups.yahoo.com/group/IC746/files/IC746-faq.pdf Mirrored copies (after a short delay) appear at: http://www.qsl.net/kb9sss/IC-746/IC746-faq.pdf...

  • Page 10: What Are The Future Plans For The Faq

    Acrobat Reader, available for free from: http://www.adobe.com/products/acrobat/readstep2.html Most of the power supply information should be separated out into a separate FAQ that is applicable to all rigs. This fits in better with the new ICOM Resource pages at: http://www.qsl.net/icom/ Page 10 of 113...

  • Page 11: What Questions Still Need To Be Answered

    IC-746 FAQ What questions still need to be answered? There are plenty of topics that still need or deserve to be covered. Here are some topics and details we'd like information on (in no particular order): • Levels and impedances of all audio connections (mic, phones, acc, etc...) •...

  • Page 12: General Info

    Should I buy an IC-746? Yes. Try it, you'll like it. This FAQ is maintained by happy, loyal, and devoted IC-746 owners. What do you really think we're going to say? One thing nearly everyone (both loyalists and detractors) agrees upon is that you should make every effort to try out a rig before purchasing it.

  • Page 13: Where Can I Buy/Sell A Used Ic-746

    1077. http://groups.yahoo.com/group/IC746/message/1012 http://groups.yahoo.com/group/IC746/message/1023 Where can I buy/sell a used IC-746? Usually when someone asks this on the internet, they are looking for an on-line swap page. There are, of course, plenty of other options. Most dealers have used/demo equipment.

  • Page 14: Is There A Dedicated Hf Net For The Ic-746

    (site not responding Jan-2002) Ham Shopper: http://www.hamshopper.com/ Good luck. Is there a dedicated HF net for the IC-746? Yes, one was started in October 2001. It convenes 20M SSB near 14.2525 Mhz +/- QRM, on Sunday evenings at 9:00pm Eastern time (6:00pm Pacific).

  • Page 15: Are There Electronic Copies Of 746 Instruction Manuals

    The chat room should be up about 10 minutes before net. We've heard of a few other HF nets devoted to Icom equipment in general. They meet at: Sunday, 1700 UTC, 14.315 Mhz ssb Sunday, 2100 UTC, 14.317 Mhz ssb...

  • Page 16: Are There Electronic Copies Of 746 Service Manuals

    Japan has a 3rd Class license that is power limited (sort of like the defunct US Novice class). The IC-746s is identical to the IC-746, except that it caters to this limited operating class. It's output power is limited to 10w on HF and 20w on VHF.

  • Page 17: What Is The Ic-7400

    746-PRO is the English version. We don't know yet what else (if anything) differentiates them besides their name. There are two ways to look at the IC-746-PRO. Some view it as a beefed up IC-746 while others view it as a watered down IC-756-PRO. On the outside, it looks and operates very much like the IC-746.

  • Page 18: Where Can I Find Info On Other Icom Rigs

    Where is info on the 706, 718, 756, 765, 735, ... This FAQ is devoted to the IC-746. As of November 2001, we do not know of any FAQ's devoted to other Icom models. However, as of Jan-2002, a project was underway to start accumulating and centralizing Icom information at: http://www.qsl.net/icom/...

  • Page 19: What Articles Have Been Written About The Ic-746

    The definitive collection of "mods" for all makes and models of amateur radio equipment is http://www.mods.dk/ Yahoo Groups hosts more than 40 e-mail/WWW discussion groups related or devoted to Icom equipment. Here are some of the more than 50 Icom related groups there. http://groups.yahoo.com/group/icomr2 http://groups.yahoo.com/group/ICOMR3 http://groups.yahoo.com/group/ic706...
  • Page 20 A Microphone Adapter for the IC-706 Davidson, Taylor, N4TD May, 2002, QST, p.38 Describes a microphone preamp/control project that could be easily adapted to the IC-746. A Quality Sound Card Interface for ICOM Rigs Lewis, Bob, AA4PB March, 2002, QST, p.31 A great way to capitalize upon the ACC ports.

  • Page 21: Can I Transmit 100W At 100% Duty Cycle On Cw, Ssb, Rtty, Psk, Etc

    Thompson, Nigel, KG7SG April, 1993, QST, p.32 Uses the band signal on the Icom ACC connector to remotely switch between antennas with a single feedline. (This article predates the 746, but is still appliccable) Everything You Always Wanted to Know About Hardware For Computer-Controlling...

  • Page 22: I Thought The Lcd Was Blue, But Photos Show It As Green

    No, as shipped, the IC-746 will not transmit on the 60m band. No, there is no 60m specific mod to the rig. Yes, there is an all-band mod that will allow the IC-746 to transmit on the 60m band. See: http://www.mods.dk/ Of course, once you've opened up ALL of the bands this way, appropriate caution is dictated.

  • Page 23: Accessories

    Accessories Power Supplies 3.1.1 What power supply should I use with the IC-746? Short Answer Any good quality, communications grade, power supply rated at least 20 amps or more (continuous duty) should do just fine. However, most of us use larger supplies (for a variety of reasons).
  • Page 24 IC-746 FAQ http://www.arrl.org/members-only/prodrev/pdf/pr0009.pdf Transportability The larger the capacity, the larger and heavier the supply. If size and weight are critical for you, consider a "switching" supply as they are usually less than half the size of a "linear" supply. Electrical Noise All supplies generate some electrical noise.

  • Page 25: Continuous Vs. Intermittent Load

    Thus, the recommendation that your supply should handle 20 amps (or more) continuously. It is possible to run the IC-746 with a smaller supply, but extreme caution and discipline are required. Very few, if any, of us recommend it for normal operation.
  • Page 26 Strain leads to wear-and-tear. So it can be argued that a bigger supply should last longer. The IC-746 is rated at 20 amps max, but loads as high as 21-22 amps have been measured. "Your mileage may vary" definitely applies.
  • Page 27 IC-746 FAQ Other and future rigs may have greater power demands (like the 756pro). Extra capacity now may avoid the need to upgrade your supply in the future. You might well spend most of your time in a low power situation (SSB QRP) and get by with less than 5A.

  • Page 28: Antennas

    Just be sure you do use an antenna. The IC-746 does not like to transmit into an open load (no connected antenna). It will put an undue (and possibly fatal) strain on your output transistors.

  • Page 29: What Range Can The Automatic Antenna Tuning Unit (Atu) Handle

    What range can the automatic antenna tuning unit (ATU) handle? Officially, the automatic ATU in the IC-746 can handle SWR mismatches of up to 3:1 on HF and up to 2.5:1 on 6 meters. In practice, many people get even wider ranges, a few as high as 7:1, but be wary of pushing the ATU that hard.

  • Page 30: Does The Internal Atu Work On Receive

    IC-746 FAQ Many people use an external ATU along with their IC-746. Usually, they leave the external ATU switched to "bypass" and let the internal ATU do its thing. For troublesome bands/antennas, they turn off the internal ATU and engage the external one.

  • Page 31: How Do I Use A "Beverage" Antenna

    A possible problem we haven't already mentioned may stem from the possible similarity between the IC-746 and the IC-756. The IC-756 users have been warned not to use either their "Auto Tune" or "PTT Tune" features while on 6m. (even the manuals mention this, although in passing).

  • Page 32: How Do I Tune Up In Cw Without A Key

    Tuning at the antenna is far more efficient than tuning in the shack (feedline SWR, etc...), however tuning in the shack is more convenient (no power or control cables). Icom tuners will be "plug-n-play" with the IC-746, while third party tuners may require cabeling or a change in procedure.

  • Page 33: Can The Tuner Button Activate An External Automatic Atu

    3.2.14 Can the TUNER button activate an external automatic ATU? Yes. The IC-746 has a connector designed to directly connect to the Icom AH-4 automatic antenna tuning unit. Page 80 in the instruction manual describes hookup and operation. Once installed, pressing the TUNER button for 2 seconds will cause the rig to transmit 10w in CW mode until the AH-4 finishes.

  • Page 34: Why Doesn't The Rig Swr Meter Match My External Swr Meter

    Sure, the page says its for the IC-706, but the external ATU interface is identical to that of the IC-746. Once wired up, operation will be just like for the AH-4. Finally, you could just fake the IC-746 into thinking that there is an ATU out there with a dummy plug like that available from W2ENY at: http://members.fortunecity.com/w2eny/tenatuner/...

  • Page 35: How Do I Repair The Detector Diodes In The Internal Atu

    820pf caps near the open core inductors.. If you have trouble locating it from the description above, you'll either need the manual from Icom to locate the two diodes, or I have a picture that I took is available showing the location.
  • Page 36 IC-746 FAQ Page 36 of 113 2003-02-08...

  • Page 37: Microphones

    Finally, the Icom microphone input is at a relatively high impendence (1-2K ?). A matching transformer (or preamp) will yield the best results. Most microphones operate at only 600...

  • Page 38: Can I Use A Heil Microphone With The Ic-746

    IC-706 series. 3.3.4 How do I adjust the IC-746 for a Heil headset? In theory, the IC-746 has enough microphone gain to use an unaided Heil microphone. Heil's May, 2000, newsletter discusses this topic, see: http://www.heilsound.com/newslettermay00.htm In short, you use moderate mic gain (50-75%, 12-3 o'clock position) along with moderate compression (8-10db, 12-1 o'clock position) for the best results.

  • Page 39: What Are The Pin-Outs On The Microphone Connector

    IC-746 FAQ Another good QST article on microphone preamps is: "Adapting the Astatic D-104 Microphone for use with Modern Transceivers" QST, Aug, 1999, p.34 a copy of which can be found at: http://members.aol.com/ampmicro/ Another interesting design can be found at: http://www.muzique.com/ssm2166.gif...

  • Page 40: Keyers

    How do I wire up my paddles for use with the internal keyer? Short Answer Yes, virtually any type of key/keyer can be connected to the IC-746 via either the front "Elec Key" jack or the back key jack. However, the two jacks require different wiring, and only the front jack will give access to the internal electronic keyer.

  • Page 41: Can I Use The Internal And External Keyers At The Same Time

    IC-746 FAQ ring sleeve oooo ==== ]]]]]]} ---------> 3 cond wire to paddles (dit) (dash) To set the radio to use the internal electronic keyer, You do have to go to the "key", "set" menu and tell it you will be using paddles. See Page 23 and page 27 in the operation manual.

  • Page 42: Amplifiers

    Icom has instructions for this on their WWW site at: http://www.icomamerica.com/support/documents/pw1-746.html They state: 1. Make sure the CT-17 is powered up. Connect the CT-17 output 1 to IC-746, and output 2 to IC-PW1. 2. Power up the IC-746 and set up the CI-V communication per the IC-PW1 manual. The CI-V set up will vary between the early and the latest IC-PW1 units.

  • Page 43: How Do I Hook Up A Non-Icom Rf Power Amplifier

    "$10 Radio Shack" interface, talking to the IC-746 in CI-V address 56H) then the PW-1 can become confused and stop talking to the IC-746. One solution to the problem is to set both the IC-746 and DX4WIN for CI-V address 54H - the same as the PW-1.
  • Page 44 Internet Search Searching for "OMR-109" on the Internet did turn up a curious tidbit. Icom has used the OMR-109 before, as the SEND relay (RL2) in the IC-761. It had problems too. There is a Service Bulletin (#24287-001A) entitled "Larger relay for keying non-ICOM amplifiers"...
  • Page 45 First we see that the listed current/voltage ratings do not match anything we've seen or have been told before. Curious that. Why has Icom technical support given out at least TWO different sets of specs? One theory is that the relay specs we have are still not detailed enough.
  • Page 46 OK. To be totally fair, there are some amps out there that seem to work OK without an isolation switcher. Alpha Power, for example, uses an IC-746 daily to test their Alpha 99 series of amplifiers. They report no problems. Off course, their 25 Vdc exceeds Icom's specifications but are within the relay specifications.

  • Page 47: My Send Relay Seems To Be Stuck, What Do I Do

    My SEND relay seems to be stuck, what do I do? Ultimately, you'll have to replace it, either yourself or via Icom service. It is possible (battle field repair) to free the contacts by tapping the relay till it frees; but YMMV! Actually, it takes a fair amount od disassembly to access the relay, and this solution is temporary at best.

  • Page 48: Can't I Just Use The Acc Port To Key My Amp

    The send relay in the IC-746 (and others) closes 10 to 11 milliseconds before the start of the RF and opens about 7 milliseconds after the end of the RF. If you use a relay between the rig and the amp it had BETTER BE FAST.

  • Page 49: Why Do I Get Ic-746 Birdies When I Turn On My Ic-2Kl

    3.5.10 Why do I get IC-746 birdies when I turn on my IC-2KL? The IC-2KL is at fault, not the IC-746. A noisy, 12 volt switching supply within the IC-2KL causes the problem. The supply is in a small, shielded box on the top of the chassis, behind the meter. Cleaning and tightening the metal box and covers will help.

  • Page 50: Tnc

    IC-746 FAQ 3.6.1 How do I hook up a TNC to the IC-746? Check out the wiring diagrams available at: http://www.packetradio.com/tnc-to-radio.htm Page 50 of 113 2003-02-08...

  • Page 51: If Filters

    IC-746 FAQ IF Filters How many optional IF filters can I install into the IC-746? There are two (2) slots for optional filters in the 9Mhz IF, and one (1) slot for an optional filter in the 455Khz IF. What optional IF filters are available for the IC-746?

  • Page 52: Which Optional If Filters Should I Buy

    No word yet on how to tell them apart. While not an optional filter, W2ENY has a kit to modify the IC-746 by replacing either the stock 9Khz or 15Khz wide internal filters with a 6Khz wide filter. See the "mod" question of the FAQ for more details.

  • Page 53: Why Do Filter "Bandwidth" Or "Shape Factor" Matter

    Inrad publishes basic performance curves of most of their filters on-line. An example of a typical curve is: http://www.qth.com/INRAD/graphs/116.gif AB4OJ has a complete set of passband curves for Icom's filters on his WWW site at: http://www.qsl.net/ab4oj/icom/filters/filters.html Several companies have good on-line treatments describing basic filter characteristics, complete with diagrams.

  • Page 54: Can An If Filter Be Too Narrow

    Inrad filters tend to outperform the Icom filters for this application. For example, the stock Icom filter in the 455Khz IF has a -6db bandwidth of 2.4Khz and a - 60db bandwidth of about 5Khz. That gives it a shape factor of approximately 2.1. The comparable filter from Inrad has a shape factor of 1.6, a -6db bandwidth of 2.4Khz and a -...

  • Page 55: Which If Should I Put An Optional Filter Into

    Reported assembly times range from 1-4 hours per filter, depending upon the skill and care of the installer. Finally, some claim that there is an insertion loss to the Inrad filters vs. the Icom filters. However, it's been demonstrated that dropping the noise level also drops the S-meter reading, possibly accounting for the reports.

  • Page 56: How Do I Configure The Ic-746 To Use An Optional Filter

    You have to lie to the rig. All of the IC-746 filter settings are on the basis of Icom part numbers. (This is supposed to make things easier for new operators.) Just tell the rig you've installed the Icom crystal that most closely matches the one you're actually using.

  • Page 57: Why Is There Only One Optional 455Khz If Filter Slot

    IC-746 FAQ 4.19 Why is there only one optional 455Khz IF filter slot? Nobody knows for sure, but the most popular speculation is that it made the radio cheaper. 4.20 Any tips on installing 9Mhz Inrad filters? Neatness counts. Good soldering skills are a must. Most of the hams who have installed one report that it was more time consuming than they expected, but nothing they couldn't handle.

  • Page 58: What Are Some Popular Filter Combinations

    Read the above material so that you can make an informed choice. For example, one of the "best" optional filters for an IC-746 is a 2.4Khz wide crystal filter for the 455Khz IF (either the Icom FL-44A or the Inrad 109). The superior characteristics of these filters over the stock ceramic filter probably improve every one of the important receiver specs.

  • Page 59: Computer Control

    It's also the most expensive option and requires external power. If all you want to do is connect up a single rig, then Icom's WWW site lists the OPC-662 remote PC control cable as the official part. If you can find it, then great. Most people can't.
  • Page 60 "Everything You Always Wanted to Know About Hardware For Computer-Controlling Modern Radios" Blackburn, Wallace, AA8DX February, 1993, QST, p.37 "A Low-Cost PC Interface for ICOM Radios" Thompson, Nigel, KG7SG July, 1992, QST, p.37 Far Circuits has some of the required PC boards at: http://www.farcircuits.net/...

  • Page 61: Do I Need A Special Cable To Connect A Ct-17 To An Ic-746

    QSY and mode-change reports) and for external amplifier control. It was only natural to adapt it to computer control. The basics of the protocol are documented in the IC-746 Instruction Manual on pages 74-75. However, most people will prefer the documentation available from DF4OR's WWW site at: http://www.plicht.de/ekki/civ/...

  • Page 62: What Is The Ci-V Address Of The Ic-746

    There are several choices (compromises?) available. On one end of the spectrum, we have programs that replicate nearly all of the IC-746 controls on the computer. On the other end, there are programs that do computer assisted contact and contest logging.
  • Page 63 IC-746 FAQ Last word we know of (January 2001), Icom had no plans to update/fix/enhance the RS-746 software. RT Systems software OK, so Icom refers us to RT Systems at: http://www.rtsars.com/ However, as of May 2001, RT Systems does not have a 746 control program. They told N8AVX (in February 2001) that they had no plans to do so either.
  • Page 64 A package that integrates well with the DxLab software suite. More details at: http://www.qsl.net/civ_commander/interface.jpg One of IRC's claim to fame is selectable skins. You get to choose what you want your radio to look like, be it IC-746, IC-706, or even a 007 spy watch. More details at: http://n9zle.tripod.com/ ScanCat Very extensive scanning support, including automatic digital recording to your hard disk, http://www.scancat.com/...

  • Page 65: Why Doesn't Computer Software Update Freq When Tuning The 746

    Make sure you've set this option in the IC-746 if your software supports it. With CIV Transceiver not enabled, rig control software must periodically "poll" the radio to determine its current frequency and mode.

  • Page 66: Problems And Clarifications

    IC-746 FAQ Problems and Clarifications What's that funny rattling noise I hear when I first power on? Often, it’s the internal antenna tuning unit. The relays make audible clicking/rattling sounds. What's that "click" I hear as I tune across certain frequencies? The clicking noise you hear is very likely from the relays for the rig's preselector (the service manual calls them RF filters).

  • Page 67: Why Isn't My Output Power Up At 100 Watts

    Low DC supply voltage. As shipped, the IC-746 really wants a full 13.8 V dc to yield full output power. While the rig can operate at voltages as low as 11 V dc, power starts dropping off as soon as you drop below 13.5 V dc.

  • Page 68: The Rf Driver Transistors May Have Failed

    The RF power amplifier transistors may have failed. In the IC-746, there are separate PA's for HF/6m and 2m. Each PA uses a matched pair of 2SC2694's. If you’ve lost power from one but not the other, then this is a strong possibility.

  • Page 69: Cw Break-In Turned Off

    Whereas, page 84 says 13.8 Vdc +/- 15%, which is about 11.7 - 15.8 Vdc. Despite what the manual says, some IC-746's run at voltages as low as 11.0 V dc. The highest "drop-out" voltage reported so far has been 11.4 V dc.

  • Page 70: The Backlight In My Lcd Has Stopped Working. What's Wrong

    It's not the actual 'lamp' itself, but one of the driver transistors. The lamp is fluorescent, and will probably never wear out. Even if it did, the lamp isn't available as a separate part; it's part of an assembly you need to get from Icom. Background into problem There is a DC/AC converter driving the "lamp".
  • Page 71 The repair One of the techs at MTS (a company that repairs Icom gear) told K8UT that the repair is not difficult, but he does not recommend it to those without soldering/desoldering experience.
  • Page 72 IC-746 FAQ no dust behind the plastic screen is a pain. Get yourself a small can of workshop compressed air or CO2 if you can. VK4TZL (Glenn) reports: "The actual repair is relatively easy...assuming that Q302 is the problem. The whole repair took me one hour.

  • Page 73: Is There Some Way To Get The Icom-746 To Generate Dtmf Tones

    14 DTMF memories. However, beware, as VE4HAY reports that the DTMF pad on the HM-56 will also work with the IC-746, but it's scan buttons will not. We have to be careful of the 'exact' model numbers.

  • Page 74: Why Don't My "Band Edge Beeps" Match The Us Amateur Bands

    Can I transmit all the way out to the "band edge beeps"? Yes, you can transmit all the way out to the beeps. The IC-746, as shipped from the factory, can transmit outside of the amateur radio bands. This has been tested and confirmed on several rigs via dummy loads.

  • Page 75: How I Reset Back To Factory Default Settings

    6.13 How I reset back to factory default settings? The procedure is listed on page 81 of the Instruction Manual as well as on Icom's WWW site http://www.icomamerica.com/support/cpureset.html#amateur While pushing in [F-INP] and [M-CL], push [POWER] to turn power ON.

  • Page 76: How Do I Adjust The Lcd Display

    Sometimes, the NB will generate more noise than it removes. The IC-746 NB is operating within the first IF, where the passband is about 15 Khz wide. Any impulse like component of a nearby strong signal may activate the NB, again possibly doing more harm than good.

  • Page 77: How Do I Get Rid Of Ignition Noise

    • Ground the fuel pump and add RF suppression • Check the tachometer as a noise source • Add RF chokes to remote head cable (not applicable to the IC-746) • Put snap-on ferrite beads on the electronic ignition-wiring bundle.

  • Page 78: How Do I Fix A Loose Rubber Grip From The Tuning Knob

    IC-746 FAQ The IC-746 Service Manual does have an adjustment procedure for the NB on page 5-10. Icom Tech Support provided W7GJ with a PDF copy of that page around Jun-25-2001. That PDF file is now available from several places.
  • Page 79 Tucker, GA. 30084 Phone: (770) 939-1320 Houston Amateur Radio Supply George Phone: (281) 355-7373 While not "authorized" by Icom, the following repair shops have excellent reputations, particularly for out-of-warranty repairs or for older equipment. http://www.angelfire.com/biz2/mts/ Email: mts@plix.com Malcom Technical Support (MTS) 3617 Deep Lake Boundary Rd.

  • Page 80: How Do I Fix Scratches On The Lcd

    IC-746 FAQ Phone: (770) 939-1320 Tim Moes Email: tcmmoes@yahoo.com Watertown, SD RadioWorld http://www.radioworld.ca/ Email: service@radioworld.ca 4335 Steeles Ave W. Toronto, Ontario Canada, M3N 1V7 Phone: 416-667-1000 Fax: 416-667-9995 And of course, you could always just run down through the list of authorized dealers at: http://www.icomamerica.com/dealers/index2.html...

  • Page 81: Why Does The S-Meter Seem Low On 2M Fm

    IC-746 FAQ 6.23 Why does the S-meter seem low on 2m FM? While this is apparently common on many modern multimode rigs, we do not know precisely why. The S-meter sensitivities published in the QST product review did not show a problem on 2m.

  • Page 82: Modifications

    What TX/RX "mods" are there for the IC-746? "mod" is slang for "modification". Most people who ask about modifying their radio are looking for ways to make the IC-746 transmit or receive additional non-amateur RF bands. The 746 already has general receive coverage from 0.5 to 60.0Mhs, so no "mod"...

  • Page 83: Safe 2M Tx/Rx Sequencing

    Finally, W8FN (Randy) says: To do this modification, you first need to obtain some of the Icom PC connectors used to make internal RF connections. The female (PC board mount) connector is P/N 93602690 and the male connector is P/N 93602689. About 18 months ago the Icom price was $1.07 per connector.

  • Page 84: Increased Monitor Volume

    IC-746 FAQ dielectric. This will make it a lot easier to construct the input and output cables without melting insulation. The male PC connector is designed for crimp termination, but it can be soldered as well. I just stripped the center conductor of the coax and (carefully) soldered it into the center pin.

  • Page 85: Poor Man's Tcxo

    The stock 455 Khz IF filter is a 2.4 Khz wide ceramic. The PC board is drilled and traced for a full-fledged crystal filter (either from Icom or Inrad). In theory, replacing the cheapo ceramic filter (Murata CFJ455K) with a superior crystal filter should improve the rig's performance.

  • Page 86: I'm Brave; What Untested "Mods" Are There

    Replacing PIN Diodes in the Demodulator Likewise, it is speculated that the IC-746 has cheapo PIN diodes in the detector circuit. Again, in theory, replacing these with higher quality components (closely matched) would improve performance, in particular, the 3rd order intercept point. This mod even helps the famous IC-781, which is where the idea came from.

  • Page 87: Removing The Bcb Attenuator

    IC-746 FAQ Removing the BCB Attenuator A few folks have noticed that the IC-746 is less sensitive below 1.6Mhz. This appears to be due to an additional attenuator being switched in to protect the first RF amplifier from overload by comercial broadcast transmitters.

  • Page 88: 2M Tx/Rx Sequencer

    External Tuner Pulser This is covered in the Antenna Section as well. You can make the IC-746 think that there is an ATU out there with a dummy plug like that available from W2ENY at: http://members.fortunecity.com/w2eny/tenatuner/ Operation is similar to that for the other tuners, but transmission stops after an 8 second timeout instead of by tuner acknowledgement.

  • Page 89: Unmuffling Icom Hand Mics

    IC-746 FAQ Unmuffling Icom Hand Mics W0VD had problems with muffled audio; so he opened up all of his Icom hand mics and removed the heavy wad of felt that was in front of the mic elements. He's receiving much better audio reports now.

  • Page 90: Misc

    European versions. In Japan, the IC-746 has different auto-repeater offsets and is limited to only 50w RF output. In Europe, the IC-746 does not transmit above 146Mhz and has no auto-repeater offsets at all. There's also a version in Australia that is limited to 20/8 watts on 2m for FM/AM.

  • Page 91: What Are The Pin-Outs On The Acc-1 Connector

    IC-746 FAQ What are the pin-outs on the ACC-1 connector? Page 72 of the Instruction Manual has the full scoop. Here is a brief description. 1 RTTY High > 2.4 V dc < 0.8 V dc Current < 2 ma...

  • Page 92: What Are The Pin-Outs On The Acc-2 Connector

    Where can I get replacement power connectors? Obvious Solution The connector you need is often called an "OEM-T" connector. You can order Icom part number OPC-025A or OPC-025D from any of the major ham equipment retailers for a pre- wired cable.

  • Page 93: Where Can I Get Replacement Microphone Connectors

    In fact, the PowerWerx folks have pre-wired, PowerPole to OEM-T cables ranging from 1 to 10 feet long that are much cheaper than the Icom part (less than half the cost). You can always just snip off the PowerPole connector if you don't want it.

  • Page 94: How Does One Improve The Fidelity Of A Received Signal

    The characteristics/capabilities of the IC-746 allow this FAQ to take a neutral position in the debate. Stock, the IC-746 has a SSB bandwidth of about 2.4 Khz. That bandwidth can be widened to as much as 3.4 Khz without deleterious effects (the FAQ describes how elsewhere). Pushing beyond that point requires more effort than most people are willing to invest.

  • Page 95: How Does One Improve Transmission Fidelity

    21 - 60 Mhz range (15m thru 6m bands. In practice, each HF preamp will work on any HF band. The sensitivity of the IC-746 is so high that neither of the HF preamps are rarely needed. You'll need the attenuator more often than the preamps.

  • Page 96: How Do I Adjust The 746 For Best Am Performance

    Is the IC-746 suitable for CAP and MARS operation? For CAP (Civil Air Patrol) use, the IC-746 is compliant only for HF, and then only if it has the CR-282 TXCO option installed. It's not compliant on VHF at all. See the following for more details: http://www.ntc.cap.gov/comm/equipment/hf_equipment.cfm...

  • Page 97: How Do I Program A Non-Standard Repeater Offset

    IC-746 FAQ 8.18 How do I program a non-standard repeater offset? Repeater offsets are just a special (convenience) case of general "split" operation. If you need to set up such a repeater without changing your default/normal offset, then here's what you do (as outlined on page 35 of the instruction manual): •...

  • Page 98: How Do "Zero-Beat" A Cw Signal

    IC-746 FAQ 8.20 How do “zero-beat” a CW signal? Zero beating ensures that your CW signal is being sent at exactly the same frequency as the received signal. First, make sure that RIT is turned OFF. Then, use one of the following two techniques: •...

  • Page 99: Instruction Manual Errata

    IC-746 FAQ Instruction Manual Errata Know errors in the Instruction Manual, by page number. Page:2 Incorrect Page References (12) AF CONTROL references p.12, should be p.11 Page:6 External speaker and remote interface jacks are swapped. Page 6 has the external speaker and computer remote connectors mislabeled (reversed).

  • Page 100: Only One Bar For Cw Sidetone Level, Not Two

    IC-746 FAQ Page:27 Only one bar for CW sidetone level, not two In the CW -> KEY -> SET menu, there are 2 options that control the CW sidetone: options 1 and 2. Option 1 sets the sidetone level via the displayed bar. However, option 2 is only an ON/OFF setting;...

  • Page 101: Page:53 Enter Numbers Via Keypad, Not Tuning Dial

    If this level is exceeded, an external relay or switching transistor must be used. The 746 SEND line is designed to interface to a solid-state amplifier trigger, like those used in Icom's power amps. Many people have damaged their rigs by trying to switch amplifiers with higher voltage/current requirements.

  • Page 102: Service Manual Discrepancies

    IC-746 FAQ Service Manual Discrepancies The "Service Manual" is supposed to be the best, final word on the electronics within the IC- 746. However, the data it contains isn't always consistent. Here are the known discrepancies. Identity of Q302 Q302 on the S-Logic Board is a driver transistor for the LCD backlight. It's listing varies depending upon the reference within the Service Manual.

  • Page 103: Glossary

    Here are short expansions of some of the more common acronyms you'll encounter when reading about the IC-746. This document is not a dictionary; these are not definitions. A more comprehensive and detailed listing of terms can be found at: http://www.qrz.com/i/hamspeak.html...
  • Page 104 IC-746 FAQ Receiver Incremental Tuning RTTY Radio TeleTYpe short for Receive or Receiver Single Side Band Standing Wave Ratio Tone CoNtrol - SSB transmit cutoff TCXO Temperature Compensated crystal Oscilator TPBT Twin Pass Band Tuning Tuning Step short for Transmit or Transmitter...

  • Page 105: Contributors + Acknowledgements

    IC-746 FAQ Contributors + Acknowledgements There are two kinds of contributors to this FAQ: direct and indirect. Direct contributors have written entire passages that have been incorporated nearly verbatim. Sometimes, they are specifically authoring something with the FAQ in mind. Also, they are individuals who have been recruited to review specific sections prior to distribution.
  • Page 106 IC-746 FAQ KJ6H VE3CE Wayne M. Canada KK5DR Matt E. VE3EXT Jerry Beneteau Canada KT0K Greg Brown VE3GWX Peter Canada Dennis F. Keith Carter Canada KT3D VE3JKC Derek Hay Canada VE4HAY N0AT VE6CGX Tony Hwang Canada N0GMP Dave VE7MDL Erik...
  • Page 107 IC-746 FAQ WN2SQC SV1ENS Greece WU1T Damon C. Mike Foerster If anything, then the sheer number of people involved (more than 100 contributors from more than a dozen countries) should illustrate the collaborative effort involved in producing this FAQ. Thanks to everyone involved.

  • Page 108: Disclaimer & Copyright

    IC-746 FAQ Disclaimer & Copyright This article is provided as is without any express or implied warranties. While effort has been taken to ensure the accuracy of the information contained in this article, the author and contributors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein.

  • Page 109: Revision History

    Added Q/A about PSK31 hookups 2002.07.01 Added more info about DTMF generation 2002.07.01 Added more info SEND relay options 2002.07.01 Added more info on IC-746 HF Net 2002.06.03 Added info on 2n TX/RX seperation mod Page 109 of 113 2003-02-08...
  • Page 110 Added mod to MONITOR level. 2002.02.21 Updated Q/A on external tuner activation 2002.02.20 Added Q/A about internal ATU "gotchas" 2002.02.19 Updated Q/As on non-Icom amp hook-up 2002.02.19 Updated info on installing Inrad filters 2002.02.18 Added more TLAs to glossary 2002.02.13 Added Q/A about external ATUs 2002.02.12...
  • Page 111 Added M/E P:2 - incorrect page reference 2001.11.05 Added M/E P:77 - UT-102 installation 2001.11.05 Added section for Manual Errata 2001.11.03 More info on IC-746 net and daylight savings time 2001.11.02 More info on MARS mod by Icom 2001.11.01 Added Q/A about microphone pin-outs 2001.11.01 Separated Q/A on "mods"...
  • Page 112 Added another mirror site at qth.net 2001.10.15 Changed all newsgroup references into links 2001.10.15 Added Q/A on where to buy/sell a used IC-746. 2001.10.14 Added Q/A on other Icom rigs (756, 765, 735, etc...) 2001.10.12 More info on internal/external ATU interactions 2001.10.09...
  • Page 113 (Dayton Hamvention, WooHoo!) 2001.05.18 Updated info about an Icom HF net 2001.05.17 Added Q/A about non-SSB ALC readings 2001.05.16 Added new info about an Icom HF net 2001.05.15 Added Q/A about broken LCD backlight 2001.05.14 More information on power supplies 2001.05.01 First circulated copy.

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