Antennas - Function and Testing

86volvo04

Subject: Product

TESTING OF CARS
ANTENNAS

Group

P20 39

Date: No.

NOVEMBER 1986 104
THIS BULLETIN APPLIES TO THE U.S. AND CANADA.


The antenna is a critical component in the Volvo audio system. It functions to convert weak electro-magnetic signals in the air into an electrical signal the radio can use. Because this is not an easy task, the antenna must be operating at peak level in order to supply the radio with a strong enough signal for clean AM/FM reception.

There are a few simple tests to help determine if the antenna is operating properly.



With an ohmmeter (999 6525-3) or equivalent, check the resistance from the tip of the antenna mast to the tip of the antenna plug.

NOTE: Antenna must be in extended position.

The resistance between these two points should be less than 5 ohms.

If the resistance you checked is greater than 5 ohms, clean the antenna mast with a silicone-type cleaner. Retract and extend the antenna several times, wiping with the cleaner each time. Re-check the resistance; if there is no change, replace the antenna mast.



With the ohmmeter, check the resistance between the tip of the plug, and the ground connection on the plug, as shown. Resistance between these points should read infinite.

If the resistance you checked is not infinite, check for any short circuits at the antenna plug. If you cannot locate the short circuit, replace the antenna.



With the ohmmeter, check the resistance between the ground connection on the plug and a good chassis ground. Resistance between these points should read less than 0.3 ohms.


If the resistance you checked in step three is not less than 0.3 ohms, remove the antenna and clean the underside of the fender to insure a good ground connection.