How can I eliminate disturbances from engine on AM band? Neither MW nor LW
(also here in Europe) are useful. It seems that problems is how antenna is
coupled to the receiver.

If anybody knows anything - help.

Miha Rus, Log pri Brezovici, Slovenia

Check and see if your electrical systam in the car is grounded.

Bill, N5NOB

"Miha Rus" wrote in message
...
How can I eliminate disturbances from engine on AM band? Neither MW
nor LW
(also here in Europe) are useful. It seems that problems is how
antenna is
coupled to the receiver.

If anybody knows anything - help.

Miha Rus, Log pri Brezovici, Slovenia




Is there a coaxial cable between the radio and the antenna? If so, be
sure the shield has a good connection to the radio and the car's ground.

Frank Dresser

Miha:

With engine interference on AM, you may have one of two basic issues: First,
you may have noise conducted to the radio by the power wires. Second, you may
have noise that is picked up by the antenna because the antenna isn't (still)
properly grounded or is picking up noise rebroadcast by ungrounded
components. Fortunately, there are a number of things you can do to help.

1) make sure the ground strap between the engine block and the chassis is
intact and clean at both ends. (on some models, the negative cable from the
battery goes from the battery to the chassis, and then on to the block of the
engine. On other models, the heavy negative cable goes directly from the
battery to the engine block and there is a separate, smaller wire or braid
that connects the engine block to the chassis, usually near the firewall. In
either case, make sure the connections at all points are clean.) If you can't
find the connection, you can add a heavy wire (12 gauge or more) or a braid
from a handy bolt on the engine block to the chassis, usually at the frame
rails or the firewall. There will be several bolts already on each you can
choose from. (this affects both broadcast and conducted emission)

2) Make sure your antenna is connected well. Most antennas tend to lose
their ground connection over the years. Removing the antenna nut and cleaning
the fender a bit under the antenna mount can help a lot, especially with the
rear-mounted antennas. (this affects broadcast emission)

3) make sure the antenna cable is fully inserted into the connector of the
radio. It sounds silly, but I've run into several cars where the cable came
partially disconnected and the radio just didn't perform as well. This
usually also resulted in higher engine noise in the radio. (this affects
primarily broadcast emission)

4) check to be sure the radio itself is grounded. An additional strap or wire
from the radio chassis to the metal of the car chassis may help here. (this
affects primarily conducted emission)

5) Add a ground strap to the hood. In many vehicles, there are a couple of
little brass spring clips that make contact with the back edge or corners of
the hood when it is closed. Over time, these clips get bent or broken and no
longer contact the hood. Connecting a braid between the hood and firewall
will ground the hood, preventing it from becoming a broadcast antenna for the
noise under the hood. (this affects broadcast emission)

6) Give the car a tune up, and replace the spark plugs and wires. As spark
plug wires age, they tend to get brittle and lose their ability to suppress
the radio fields that can be generated. If you've changed from the standard
suppressor wires or spark plugs to "high performance" wires or plugs, you
will have increased the ignition noise several fold. To avoid broadcasting
engine spark plug noise, the military uses special shielded cables that look
much like coaxial cable. Also, if you've put one of the aftermarket "super
coils" on the car to improve the performance, it may be a large source of
ignition noise. Returning to a stock ignition coil could help a bunch. (this
affects broadcast emission)

You may not need to do all of the above, but maybe this can give you some
ideas of where to look for problems. Good Luck!

--Rick

Miha Rus wrote:

How can I eliminate disturbances from engine on AM band? Neither MW nor LW
(also here in Europe) are useful. It seems that problems is how antenna is
coupled to the receiver.

If anybody knows anything - help.

Miha Rus, Log pri Brezovici, Slovenia

A bad plug wire can also cause radio interfearance, but as other posters
have said, it's probably a grounding problem.


--
Respectfully,

Michael

Home Page: http://md_dxing.tripod.com/
Northern NJ
R75 w/DSP, Kiwa agc/sync & audio mods
G5RV & 200ft longwire w/ICE-180
MFJ-1048 preselector
SoundBlstr Live PC card w/five piece Cambridge
speakers & full software mixer/eq.

"Miha Rus" wrote in message
...
How can I eliminate disturbances from engine on AM band? Neither MW nor LW
(also here in Europe) are useful. It seems that problems is how antenna is
coupled to the receiver.

If anybody knows anything - help.

Miha Rus, Log pri Brezovici, Slovenia