Subject: Icom 706 Review From: randall@informix.com (Randall Rhea) Date: 29 Dec 1995 16:48:15 GMT ICOM IC-706 HF/VHF AMATEUR RADIO TRANSCEIVER Product Review, Hints and Tips, and Modifications As Of: December 28, 1995 by Randall Rhea, KG0HW OVERALL IMPRESSION "Too good to be true". This was my understandable reaction to Icom's announcement of the IC-706 amateur radio transceiver last summer. It looked like my dream mobile rig: very small size, detachable face plate, all HF bands, FSK, 6 meters with 100 watts ... AND 2 meters, all in one rig? It sounds too good to be true, but after using this radio in my car for about a month, I can tell you that this radio is real. Although the rig is not without its faults, Icom has produced an innovative masterpiece. The rig does just about everything as advertised. It is an easy-to-use radio that replaces several other radios that I was operating in my car. Over the Christmas holidays, I took a couple of long car trips here in Texas. The 706 was installed under a car seat, leaving plenty of room for luggage and packages. (Do NOT block the top of the rig. Leave room for air circulation. The rig gets VERY hot when transmitting!) The face plate was installed just below the dash within easy sight when driving. I used headphones, so my wife and daughter could listen to CDs while I was working DX. The headphone plugged into the face plate. I used a 7-foot whip mounted on the trunk of the car tuned for the SSB portion of 6 meters, my favorite band. The radio was a pleasure to use, even while driving. During a nice opening on 6 meters on the evening of December 27, I worked several new grid squares in the midwest and Arizona. I also worked North Dakota for the first time. I was able to work a station in Mexico City quite easily, despite the pileup. That 100 watts sure helps. (I previously used a 10-watt rig.) The sensitivity of the receiver, although not quite what the "pros" would want, was quite adequate. Noise from the car engine was only a minor problem; the noise blanker was effective for SSB. During the trip I also listened to a football game on TV channel 2, listened to truckers' traffic reports on CB channel 19 (27.185 MHz), worked a couple of 10m stations during the sporadic E opening on December 27, worked a couple of 20m stations, listened to WWV on 2.5, 5, and 10 MHz, eavesdropped on some interesting baby monitors and cordless phones on 49 MHz, listened to NOAA weather forecasts on 162.55 MHz, monitored some aircraft traffic, and did some ragchewing on 2-meter repeaters. Not bad for ONE radio! PRICE I paid $1249 for mine at Tucker Electronics in Dallas. They told me that they have sold about 200 of them in six weeks, making the IC- 706 their best selling rig of all time. They are getting them from Icom in lots of 20 and are having trouble keeping them in stock. Prices for accessories are pretty high. There is little profit margin in the box, so they make up for it with high accessory prices. The cable to allow for front-panel detachment is $48. UNIQUE FEATURES AND INNOVATIONS See http://www.icomamerica.com/icom/amateur/hf/#IC-706 for a list of features. * The smallest HF rig on the market (similar in size to the Kenwood TS-50) * Detachable face plate with a jack for a speaker or headphone. The mic plugs into the face plate using a plug similar to a modular telephone plug. (A spare plug is included.) The cable to allow for this detachment costs extra. * Full HF/VHF transmit coverage from 1.6 to 54 MHz and 144-148 MHz (the rig transmits only on the ham bands out of the box, but an easy modification unlocks the transmitter, see below) * General coverage receive from 50 KHz to 163 MHz (requires modification, see below) Rig receives up to 200 MHz but with poor sensitivity above 162 MHz even with the modification. You will be able to receive: longwave, AM broadcast band, shortwave broadcast, all amateur bands in all modes from 160m to 2m, FM broadcast band (wide FM), aircraft (118-136 MHz AM), VHF from 30 MHz to about 162 MHz, US TV channels 2 through 6, NOAA weather at 162 MHZ. * 6 meters and 2 meters, all-mode * 100 watts on HF and 6 meters (10 watts on 2 meters) * Innovative, easy-to-operate menu system. It becomes quite easy and natural to use after reading the well-written manual for about an hour. (In contrast to my Yaesu FT-470 HT, which I still cannot figure out.) * The manual is very well written, with lots of easy-to-understand diagrams. * Simple, but useful and configurable band scope. (Previously available only on very expensive rigs like the Icom 781.) This allows you to examine nearby frequencies for activity. * Split frequency operation appears complicated at first, but the rig's "quick split" mode makes it fast and easy. * Built-in electronic keyer at no extra charge. The Up/Down buttons on the mic can be used as a paddle. This has rejuvenated by interest in CW. I worked a couple of slow CW stations on the novice portion of 80m, which made me remember how fun CW is. * FSK (Nice feature for this price range) * DTMF and programmable offset for repeaters and split frequency work * Good audio reports from contacted stations. A station on 3.85 MHz reported "a very good signal for a mobile". A 2m FM station reported "very good audio ... so that's the 706 I've been hearing about." * Works very well with the AH-3 antenna tuner. This is the Icom HF (1.8-30 MHz) random wire tuner that worked with the 725. The tuner is mounted under the trunk lid of my car with cable ties. It can also be mounted outdoors. It will tune any 8-foot whip or wire for any HF band. (You need 40 feet for it to tune to 160m.) You can press a button to enable the tuner, or the tuner can fire off automatically if your SWR is too high. With my 7-foot 6-meter whip, I can tune to any HF band above 3.5 MHz. That means I need only one simple antenna for HF and 6m. * 100 memories that store frequency, split offset, mode, and FM tone. * Two antenna connectors: one for HF/6m and one for 2m. The connectors are switched at 60 MHz. * Jacks for remote speaker and/or headphones on both the face plate and the back of the rig. * Multifunction meter: S meter, SWR, relative power output, ALC. DRAWBACKS/FLAWS * Extended VHF receive requires modification (see below). * Poor sensitivity above 162 MHz. * Noise blanker does not work on AM. Very irritating pulse noise on AM while the car's engine is on. The blanker works well on other modes (except FM, where it is not needed). Not good for listening to AM while driving. A rather serious flaw in my opinion, since my $40 CB has a noise blanker that works well. * Poor QSK (full break-in) capability. Not recommended for high- speed CW operators who want QSK. Use semi-break-in instead. * No CW narrow filter. You can install one as an extra-cost option or use an external CW filter or DSP unit. * The built-in speaker provides surprisingly good audio for its size, but you will probably want to use an external speaker. The speaker can be connected to the face plate or to the rig itself. * Automatic repeater offset is not programmed into the rig. You need to program -600 or +600 yourself through the menu system. This is not a problem if you store your favorite repeaters into one of the 100 memories. * The S-meter is inaccurate below S9. Above S9, it is quite accurate. * High prices for accessories (typical of just about all other vendors) * The AH-3 antenna tuner is shipped with an unshielded cable, which picks up a lot of auto engine noise. You need to make your own shielded 4-wire cable. The AH-3 also blocks signals above 54 MHz. It also only works for HF, not for 6m or 2m. * Expect performance and receiver sensitivity similar to other rigs in this price range. This is a low-end rig in terms of price. For price vs. performance, this is probably the best amateur radio of all time. However, it will not outperform your $4000 rig. You probably won't win contests with it. You will have a lot of fun and own a nearly ideal rig for mobile work. HINTS AND TIPS 1) Take time to read the manual. The menu system will be bewildering unless you read the manual. One you get used to it, you will find the rig to be amazingly easy and fun to use. 2) You need to set the mode to wide FM to receive FM or TV broadcasts. Tune to the station, press the MODE key until the front display shows FM, then press and hold the MODE key for 2 seconds. WFM will appear in the display, and you will hear the station with nice audio. 3) Don't use the noise blanker on AM. It will not be effective and may distort your audio. 4) Don't use the QSK feature. 5) The rig gets very hot while transmitting. Keep the top of the radio clear to allow air circulation. MODIFICATIONS WARNING: Improperly performed modifications can severely damage your radio. I have performed these modifications successfully, but I offer no guarantee or warranty for them. Proceed at your own risk. TOOLS NEEDED: 1) Small philips-head screwdriver 2) Tweezers 3) Magnifying glass 4) Low-wattage (15 watt) soldering iron 5) Long-nosed pliers MODIFICATION 1: Enables out-of-band transmit for 1.6 MHz to 54 MHz. This does not enable extended VHF transmit; a modification for this may be available soon. This does not enable AM or FM broadcast band transmit. Your memories will be cleared after this modification, since you need to reset the CPU. 1) Open the top of the radio by removing the 3 top screws and 2 side screws. Look at the radio from the with the front panel facing you. screws. 2) Gently pull up the speaker and set is aside without damaging the speaker or the wires that attach it to the rig. 3) Note the silver rectangular box near the middle of the PCB marked something like "9 MHz SSB Filter". 4) Move your eyes up from this filter toward the back of the radio. Just before you get to the "D 108" marking, you will see two tiny diodes, two blank spaces, and one additional diode. They look something like this: D108 [XX] [XX] [ ] [ ] [XX] Remove this diode ^^^^ 5) The second diode from the left needs to be removed. I did this by crushing it with long-nosed pliers. You can also heat it with a low-wattage soldering iron and pull it up with tweezers. Be sure not to damage the other diodes or the PCB. Be sure that you don't apply too much heat, since the heat can damage the PCB and the other diodes. 6) Re-assemble the radio. Reset the CPU by pressing and holding down the UP and DOWN buttons on the front panel and pressing POWER. MODIFICATION 2: Enables more sensitive transmit above the 2 meter band. (148 to about 162 MHz; after that, sensitivity drops off.) Keeps sensitivity for the FM broadcast band. 1) Open the top of the radio by removing the 3 top screws and 2 side screws. Look at the radio from the with the front panel facing you. 2) Note the silver rectangular box near the middle of the PCB marked something like "9 MHz SSB Filter". 3) Move your eyes up from this filter toward the back of the radio. Follow the ribbon cable up. Notice a wide white connector with several colored wires in it on the back of the PCB. 4) The fourth wire from the left is a yellow wire. Cut this wire. Rather than cutting it, you can remove the connector, stick a paper clip in the side of the connector under the wire, push it in, and pull the wire out. Be careful not to remove the other yellow wire. 5) Re-insert the connector back to its original place on the PCB. 6) Open the bottom of the radio. You will again need to remove 5 screws. 7) Look at the radio with the front panel facing you. Note 5 tiny transistors behind the MENU button. Follow the trace from the middle transistor to a hole just to the left of jack J8. +------------------------+ | | * [XX] [XX] [XX] [XX] [XX] +-O *** J8 * Solder wire into this hole ^ 8) Solder a small wire into this hole. Be careful not to apply too much heat; use a low-wattage soldering iron. Be careful not to damage the PCB or the grey cable coming out of J8. Use a magnifying glass. 9) Run the other end of the wire you just soldered to the front of the radio and attach it to the yellow wire you just cut. 10) Re-assemble the radio. - END OF DOCUMENT -