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Author Topic: Icom 706mkIIg RF Hash Form mic?  (Read 199 times)
N4CQR
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Posts: 566




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« on: August 01, 2007, 03:04:01 PM »

I have the above mentioned radio. With the mic plugged into the control panel (head) I have an irritating hash on 10 meters every 15kHz. The best I can describe it is being similar to the display noise generated in the Grundig Satellit 800 Millennium around the 20mHz region. (And Drake SW8 too for that matter.)

Is this generated from the LCD? If I plug the mic into the jack on the rear of the radio, the problem goes away.

This is the first and only 706 I have owned so I have no, none, zero experience with the radio. Nothing in the manual, that I found anyway, specifically addresses this issue – assuming it is one.

TIA
Craig




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N5KRC
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« Reply #1 on: August 01, 2007, 03:22:44 PM »

There is a tiny screw that is used on each end of the separation cable.  Make sure you have both screws in place and that they are tight!  The screw is actually what grounds the control head to the main body.

I had similar problems when I ran a MKIIG mobile, and I even had the both screws in.  However the screw on the main body side was about a quarter turn loose.  Torqued it down and my problems went away.
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N4CQR
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« Reply #2 on: August 01, 2007, 03:49:24 PM »

Scott, thanks for taking the time to reply. I am not using the seperation cable. Just the radio sitting on the desk.

The mic that came with the (used) radio is a MH-103 and according to the manual, that is the correct one.
Also according to the manual, the rear connector  is parallel with the front one. Hence, why the noise on the front connector and not the rear.

Thanks again, Scott

Craig
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K0BG
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« Reply #3 on: August 01, 2007, 04:11:14 PM »

Actually, if you have the service manual, you'd see that the rear and front panels connectors are NOT exactly duplicates. Although not widely reported, the aforementioned "hash" is a known issue with some early production models of the MkIIg.

Alan, KØBG
www.k0bg.com.
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N4CQR
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Posts: 566




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« Reply #4 on: August 01, 2007, 04:31:41 PM »

Alan, thanks for the info! My comment about the connections being parrllel was taken from the manual and that is all I have to go on.

Well, I don't recall the serial number righ off but 20xx comes to mind. While the problem is irritating, it is only on 10 meters and only every 15kHz. And tapers off towards 28.3 and 28.5. (figers!)

The obvious work-around is to use the rear mic connector when I am on 10 meters. Or any band for that matter.  There is no real reason for me to switch mic inputs back and fourth. I just like to keep the radio on 28.400mHz while I am tinkering around.

At this point, I think I will leave well enough alone. The radio works fine and exibits no other strange and unusual characteristics.

I really appreciate you folk's input.  

Craig

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K5LXP
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« Reply #5 on: August 01, 2007, 08:01:53 PM »

Do you pick it up with the rig connected to a dummy load, or the antenna disconnected?  

Mark K5LXP
Albuquerque, NM
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