Re: [IRCA] After Market Radio

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

> 1. My truck suffers from really bad ignition noise. It has had this
> problem since the day I bought it. How do I troubleshoot to get rid of
> this. It varies in intensity with the speed of the engine, so I assume
> it is spark plug related. I have had it tuned several times and each
> time told them about the problem.  I think the repair guy did not quite
> understand. What should I do?

Most gasoline vehicles do have a fairly nasty ignition noise.  I've worked
for years to eliminate that, going back to the 70's.  I've tried such things
as running the radio off a separate battery that isn't connected to anything
else.  Tried making a shield harness out of 1/2" soft copper tubing for the
ignition wires.  Ground straps to all body parts and the frame, grounds from
the exhaust system to the frame.  Filters of all sorts in various places of
the 12v electrical system.  I did find a copy of what is done on police
vehicles to minimize noise, and copied that.  Some reduction, but little
real progress.

However, a couple of months ago I tried something.  I got an Alpha Delta
ATT3G50U SO-239 lightning arrestor and bolted it to the truck floor.  The
floor was scraped down to bare metal to be sure of a good ground.  I
replaced all the antenna cable with as good RG-58 as I could find.  What
happened is the truck electrical noises nearly vanished.  I could listen to
quite weak stations while driving.  Previously even the 50kw Boston stations
were noisy.

> 2. Is there some way to inductively connect an antenna to the whip
> antenna? I touched the antenna with my hand and it got a little more
> gain, enough on some of the weaker signals, that they become audible.
> Anyone had experience with that?

I would recommend buying a Radio Shack CB whip and cutting it down to 68".
Then mount it on the rear bumper.  Moving it as far from the engine as
possible does help.  You may try winding a dozen or 18 turns of the coax
through a large toroid.  This will make a choke and reduce noise coming in
the cable.

> 3. I also have a problem at certain speeds when loud crackling noises.
> It goes away at low speeds.  I suspect it is an antenna shorts or open
> connection.  Any ideas anyone?

As engine RPM and load increase, it takes a higher voltage to jump the spark
plug gap, and more noise.  Alternator whine tends to have a much smoother
and cleaner sound than ignition noise.  Also has a higher pitch.  If it's
alternator noise, they do make filters for that.

I have been looking for a Cummins 4BT diesel engine to swap into my truck.
It has no electronics at all on the engine, except the alternator.  So,
noise will be significantly less.  Mileage will double as well..

Craig Healy
Providence, RI

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