[ICOM] Running mobile with some CW problems

[Larry Benko]

John,

I have run mobile for years with over 50k /m QSOs.  "RF bites" occur for 
one reason only: There is RF voltage on the radio chassis relative to 
the car chassis (your body is at the car chassis potential).  The most 
likely culprit in your case is the DC feed RF impedance.  The radio has 
a ground tab on the back of the case and I would connect it to the 
vehicle chassis near to where you have the radio mounted.  Then I would 
put a "decent" common mode choke in the DC feed near the radio.  6 to 8 
turns on an FT-240 #31 material core or something like 4 turns thru 
Mouser #623-0431176451, $6.30ea.

73,
Larry, W0QE


On 8/6/2013 3:36 PM, John Geiger wrote:
> I was running my Icom 706MKII mobile over the past few days and made quite a few QSOs on the County Hunters Net.  However, 2 interesting things showed up, that I am looking for solutions for.  I had my 706 plugged into the cigarette lighter on a 2007 Chrysler Town and Country Minivan. The cables were 10 or 12 guage so there shouldn't have been much voltage drop. The antenna was a MFJ mini hamstick (3 feet tall on a 5 inch mag mount) for 20 meters.  I had the rig set to 40 watts due to the current limitations of the cigarette lighter.
>
> The first thing I noticed was that I was getting RF bites off of the set up MFJ mini travel paddles I was using.  Also off of the rig case at times.  This is intersting because it didn't happen last month when I was using a Yaesu FT857 with the same setup.  The only difference was that the paddles have a 1/8" plug on the end, so they plugged directly into the FT857's key jack, whereas I had to use a 1/8' to 1/4" adaptor for the key jack on the Icom 706MKII.  Don't know if the adaptor could cause something like that.
>
> Secondly, a couple of stations told me I had a chirp on my signal, like the battery was low.  I didn't get this report when the FT857 either, running at around the same power, nor with an Icom 706 original I used to have. Could the 706mKII be more sensitive to lower voltages?
>
> I wonder if others have experienced these problems with their 7-6s or have an idea as to what could be going on with my setup.
>
> 73 John AF5CC
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