[Mobile-Portable] Radiated noise-Chrysler Town & Country van

[Peter E. Beedlow]

To all,

Looking for suggestions regarding quieting down the ignition noise in a 2002
Chrysler Town & Country van. Here's the operating environment, what I have
done and what I see as the problem
:
Vehicle information:
Vehicle: 2002 Chrysler Town & Country eX
Engine: 3.8 Liter V6

Amateur equipment installed:
Icom IC-706MIIG with the main unit installed under the rearmost passenger
seat and the control head installed on the console between the driver and
passenger seats. The radio is wired directly to the battery with a relay is
installed in the positive lead to remove voltage 45 seconds after the
ignition is turned off. The power leads for the radio were installed under
the chassis of the van to minimize the change of any interaction with the
installed van wiring harness. A heavy-duty noise filter, capacitors and
toroid transformer, is installed at the radio position with a ground lead
from the noise filter to the chassis of the vehicle.

Antenna:
Custom designed mount for a Hustler mast bolted to the tailgate of the van.
Every effort was made to ensure good grounding from the vehicle to the
antenna mount. No fluctuating SWR indications have been seen either during
radio transmissions or during testing with an antenna analyzer.

Problem and symptoms:
Ignition noise is very apparent and loud enough that it makes operation of
the installed amateur equipment almost impossible. The ignition noise is
noticeable on the factory installed AM/FM radio in the vehicle, although
typically a strong AM station will cover the ignition noise.

Measures I have taken to reduce the ignition noise:
--Spark plug wires and ignition system:
The spark plug wires were covered with tinned, copper, braid and grounded to
the engine. In addition the electronic distributor was covered with aluminum
foil.
-- Hood hinges:
Both hood hinges were bonded to the vehicle body with tinned, copper, braid.
-- Tailgate hinges:
Both tailgate hinges were bonded to the vehicle body as recommended in TSB
08-23-99.
-- Engine to chassis grounding:
The factory grounding from the engine to the chassis is rather poorly done
and I suspect will be a problem as the vehicle ages. I added a grounding
strap from the passenger side engine mount to the chassis.
-- Exhaust pipe:
The exhaust pipe is grounded to the chassis in two places using muffler
clamps and tinned, copper, braid.

There is no noise apparent with the antenna removed from the vehicle (this
is removing the antenna from the mount not removing the coax from the
radio). This indicates to me that the problem is one of radiated noise. With
the 706 noise blanker engaged I still see an S 3 to 5 noise level. With out
the noise blanker it's S7 to 9. Unfortunately although this is acceptable
(border-line!) for day-to-day operating on the county hunter's CW net, it is
not acceptable for an mobile state QSO Party operations and that is one of
my interests.

I am working with the deal and directly with Chrysler but thought I'd ask
"the experts" on this reflector and see if anyone has some ideas worth
pursuing.

Thanks and probably best to reply to me directly at nn9l@arrl.net.

73,

Pete, NN9K