amateur radio question

[Archive]

I would like to hear from fellow hams who have a 2m radio in their 98 or later truck.
My wife's 98 12V truck has intermittent interference on her 2m radio at 146. 660 MHz which is our local repeater rx freq. I took my handheld and scanned around that freq inside the truck. To my surprise I found a strong signal centered at 146. 700 (but drifting up and down) inside the truck. Stepping out I found it was stronger under the hood. Using the antenna as a probe, I localized the problem to the Controller Antilock Brake (CAB) which is rear wheel only on this truck.
Looking at the wiring diagram it is clear that the likely culprit is the CCD bus, which connects just about everything on the truck.
Whether it really is the CAB I cannot say for sure. Next I will try ferrite beads on the CCD bus as it enters the CAB.
Does anyone know where the CCD signals originate? In other words is the bus controller in the Instrument Cluster or the PCM,CAB or what?
Tomorrow I will take my portable scope out and poke around.
Thanks.
N7DAL/K9DAL.
ps forgot to mention, this problem occurs with engine stopped, key in run position.


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1997 4x4 CC 5spd, CPL1553 pump, Horton fan, Sport headlamps, Optima RedTops, 98 shift levers and console, RS5000 shocks, Yaesu VHF radio, and BCT7 scanner in the overhead console... N7DAL.

[This message has been edited by adiabatic (edited 01-22-2001). ]

 

[Archive]

i run 2 mtr hf, 6 mtr, 10 meter
w/ dk3 10-80 meter ant
dont know what setup u have mine is 93 non
computer so no problems, but from expr
always do this, run radio 12v directly
to battery i use 2nd batt , chgs when
driving only, is disconnected when parked
ground radio to frame, dont use glass
mount ant. use one thats center cab mounted, no tuners, see that all major trk
components anre grounded properly.
ill be in vegas at the may meet
can show you more there,iam kk6dm

73's bill

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1993 w350 ex cab, banks,nv 4500 in
open exaust, pw Injectors are in. Big rig flaps,tach soon to be in. Its loud and goes ok, for a 93,only beat 1 pwr strk furd. 2 optimas,
love driving it!

 

[Archive]

I run a dual bander most of the time, but have had my FT-100 in there on long trips.
I have a 98. 5 and don't have any noise problems, don't even need the noise blanker. check the TSB site, I have seen several for "2 way radio interference" on there.

Originally posted by drivers mopars:
i run 2 mtr hf, 6 mtr, 10 meter
w/ dk3 10-80 meter ant
dont know what setup u have mine is 93 non
computer so no problems, but from expr
always do this, run radio 12v directly
to battery i use 2nd batt , chgs when
driving only, is disconnected when parked
ground radio to frame, dont use glass
mount ant. use one thats center cab mounted, no tuners, see that all major trk
components anre grounded properly.
ill be in vegas at the may meet
can show you more there,iam kk6dm

73's bill

 

[Archive]

Oh yeah, in all this wiring, don't forget to fuse the positive lead AND the negative lead. I have personal experience with my first 2m (notice I said first as if I had to buy another one shortly after) #ad
YEP. Sometimes it's easy to forget.
73's

 

[Archive]

Update: I put my portable scope on the CCD bus and it is NOT the culprit. It has nice slow edges of 1us rise/fall time. It is low-level, about 200mV differential. (My scope is a Tek THS700 with floating grounds. )
So the circuitry inside the CAB must be causing the noise, or else it comes from another module like the PCM and gets conducted everywhere by the harness.
May just move the antenna.
DC created a RFI disaster on the 98.
N7DAL

 

[Archive]

I have not check for noise on that frequency but I do have a noise that is generated when at a stop or less than 30 mph on my 96. I first noticed it on 1560 khz, listening to Rush Limbaugh. I will check on vhf and see if I have something similar to your noise. I do not have a manual yet, need to get one. Not shure what kind of signal would be speed dependant and 30 or less, could be in brake system. Let me know when you find something. I will do more checking and share what I fine.
73
John

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96 CC 4X4 2500 SLT AUTO transmission, PrimeLoc, ISSPRO EGT Boost transmission Temp, GUTTED CAT, 155,000+ Miles still goin' strong, Lots of Ham Radio gear, NO IGNITION NOISE!!! Love my diesel!!! # 8 TST Fuel Plate.

 

[Archive]

I checked on vhf and uhf, with Icom 4200A, could not find a signal from truck, the noise on AM radio is only detectable with weak signal and not as bad on other stations other than 1560 so seems to be frequency signal. We could be hearing different harmonics. I will do more checking. Need to put my Icom 706 in and try it.
73
John

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96 CC 4X4 2500 SLT AUTO transmission, PrimeLoc, ISSPRO EGT Boost transmission Temp, GUTTED CAT, 155,000+ Miles still goin' strong, Lots of Ham Radio gear, NO IGNITION NOISE!!! Love my diesel!!! # 8 TST Fuel Plate.

 

[Archive]

Update: I made a shield for the antilock brake controller (CAB) out of double-sided circuit board. Grounded it to a nearby bolt. It has cured 99% of the problem for free. I was not looking forward to my conversation with the dealer.
N7DAL

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1997 4x4 CC 5spd, CPL1553 pump, Horton fan, Sport headlamps, Optima RedTops, 98 shift levers and console, RS5000 shocks, Yaesu VHF radio, and BCT7 scanner in the overhead console... N7DAL.