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Author Topic: ICOM 706MKIIG CUTS OUT AT TIMES  (Read 1275 times)
KE7WLF
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« on: November 06, 2008, 02:58:47 PM »

 have a 706MKII-G that will stop receiving and/ or transmitting intermitantly.My radio will start failing by making a rapid popping sound, then RX audio will stop. When TXing, TX light goes dim, TX/RX relay starts buzzing like a spark gap, eventually no TX at all.It is usually on 2 meter but even happens on HF.

I have changed everything from the antenna/power cable/microphone/duplexer/coax/seperation cable. The TX light flickers and it souns like a bunch of relays clicking real fast on/off, this usually happens when trying to transmit, but not all the time. It also just stop receiving if I am listening to someone speak, the sounds just goes away and the meter stops moving.
I have sent the radio to ICOM and they said after 2 weeks NPF, and sure enough when I received the radio back home, it worked for 3 days and then started doing it again. Temp makes no difference, its as intermitant any time or temp.

Any Ideas? Who else repairs radios since Icom chagred me for a NPF, they wouldn't keep it any longer even tho I asked them to keep it until it failed.
About ready to throw this radio away, cant afford another one and using it is usless to try to communicate with anyone.

Please, any idea would help. I am about the throw in the towel on the hobby.
Thanks to all
KE7WLF
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W3LK
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« Reply #1 on: November 06, 2008, 03:32:56 PM »

Sounds more like a power supply voltage problem to me.

Have you checked the output voltage of the power supply _under_load_?

73,

Lon - W3LK
Naugatuck, Connecticut
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K0BG
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« Reply #2 on: November 06, 2008, 04:09:02 PM »

Most Icom IC-706 radios will shut themselves off at about 11.6 volts. Some will go to 11.5, and a few just 11.8. When they do, the usual
manifestation is a popping sound caused by the relay starting to open. Closer to the verge, you'll actually hear the relay. Based on this, I'd say Lon is correct.

This said, there are three 8 volt regulators in the 706. The one powering the Tx/Rx control line, will exhibit the same systematics. If Icom checked like they normally do, they might have missed this specific problem. My take is, they didn't!

Alan, KØBG
www.k0bg.com
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KE7WLF
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« Reply #3 on: November 06, 2008, 04:30:20 PM »

I will monitor the Voltages next time this happens and see if it is 12v or less
Thanks
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KQ7X
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« Reply #4 on: November 06, 2008, 04:39:21 PM »

Victor,

I would echo W3LK's suggestion, and you might also consider RFI causing trouble when transmitting.  You might have a combination of power AND RFI troubles.   If/when your power supply checks out ok, but doesn't solve your trouble when transmitting, try installing one or more ferrite beads on all the cables connected to the radio, as close to the radio as you can install them (a couple wraps or more of the cable through each bead if you can).  Sources of ferrite beads would be DX Engineering, Amidon Associates, Radioworks, and possibly your local Radio Shack, as well as many others.  If you try Radio Shack, their sales associates may not recognize the term "ferrite bead"; ask for "RFI Filters", or "Interference Filters", or some variation, along with describing what they're for.

Hope this helps; the 706MKII-G is too good to toss aside!

Al
KQ7X  
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W2KYM
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« Reply #5 on: November 06, 2008, 05:53:18 PM »

I definitely would suspect a RF feedback problem. Make double sure your antennas are well grounded on the vehicle. I had that issue in my old truck as I used a mag mount antenna. Bought a new car, (I needed it anyway) and also a trunk lip mount, issue resolved!
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W3LK
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« Reply #6 on: November 07, 2008, 07:04:19 AM »

<< Make double sure your antennas are well grounded on the vehicle.>>

I don't see anywhere that this is a mobile installation. Smiley

73,

Lon - W3LK
Naugatuck, Connecticut
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KE7WLF
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« Reply #7 on: November 07, 2008, 07:29:33 AM »

This is listed in the "MOBILHAM" section.
It is in my Tundra and the antenna Comet UHV-6
is grounded to the frame, The truck's exhaust is also grounded, this reduced alot of noise, the antenna tuner AT180 is grounded to the seat track and body, the radio is grounded to the body,Comet CF-530 Duplexer
is also grounded to the body. It worked flawlessly for 2 years then the intermitant issues started to happen.
I am a firm believer in grounds and lots of them.
I do feel it is a POWER issue like others have said and will try to moniter it next week and measure voltages, especially at the fuse holder. I do really love this radio, but its frustrating.........I'll post back IF I find anything.
Thanks Everyone, I dont feel so lost now.
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KE7WLF
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« Reply #8 on: November 07, 2008, 07:31:35 AM »

This is listed in the "MOBILHAM" section.
It is in my Tundra and the antenna Comet UHV-6
is grounded to the frame, The truck's exhaust is also grounded, this reduced alot of noise, the antenna tuner AT180 is grounded to the seat track and body, the radio is grounded to the body (I WWAS TOLD NOT TO GROUND IT TO THE BATTERY),Comet CF-530 Duplexer
is also grounded to the body. It worked flawlessly for 2 years then the intermitant issues started to happen.
I am a firm believer in grounds and lots of them.
I do feel it is a POWER issue like others have said and will try to moniter it next week and measure voltages, especially at the fuse holder. I do really love this radio, but its frustrating.........I'll post back IF I find anything.
Thanks Everyone, I dont feel so lost now.
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KA1MDA
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« Reply #9 on: November 07, 2008, 06:09:23 PM »

Mine does the exact same thing, into a dummy load, on the bench, no remote head mounting kit, and 13.8V on the power connector. But then again, mine also has the intermittant low deviation / white noise on VHF TX/RX problem as well. I think the high operating temperature has just baked itinto  oblivion. I think it's related to a PLL unlock issue. I doubt it's RFI, as the problem occurs in receive mode when listening to international SW broadcasters as well.

Tom, KA1MDA
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KE7WLF
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« Reply #10 on: November 08, 2008, 07:27:58 AM »

Well it i NOT a ground or a POWER supply.
I removed the radio from the truck and used a new power supply and 2 different antennas, lots of grounds.
It happens on ALL frequencies. The backlight stays on, the frequency numbers stay on. We timd it and after 15 minutes of just being on, it started acting up, losing RX and then when keying te mic it started the relay clicking sound.
We have determined it is inside the radio, and probably the PLL's. I was told by the radio shop here in LV to find a retired ICOM tech who repairs radios as his own business. If anyone knows a retired ICOM tech who has his/her own business, let me know.
Right now http://www.w7jv.com/ has been suggested . I will contact them later next week.
Thanks everyone for your input.
73's
KE7WLF
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AC7WN
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« Reply #11 on: November 19, 2008, 11:13:22 PM »

A few years back my 706Mk2G(SN#3939) had intermittent transmit on HF. Sent it to Icom and they replaced the swr sensing diodes in the P.A. section. Ever since then it's been working fine. No more intermittent TX.
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W0FM
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« Reply #12 on: December 04, 2008, 10:57:56 AM »

If you don't have a fix by now, you might contact Scott Malcom at Malcom Technical Service (MTS).  Scott has very good Icom skills and is a pleasure to work with.  mts at trip dot net.

Knows his stuff.

73,

Terry, WØFM
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KE7WLF
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« Reply #13 on: December 04, 2008, 11:10:26 AM »

I will Try Malcom. I had e-mailed 2 other places as recommended here and another Ham site. I have received NO response from any of them and they have not returned my phone calls. Kinda makes me wonder.....
I will e-mail him tomorrow.
Thank You for the info. Maybe 3rd times a charm.
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EC158
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« Reply #14 on: December 31, 2008, 01:23:10 PM »

I had this problem with mine as well. I was using the remote kit. I wrapped the wire thru a few torroids and the problem went away.
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