Radio Tuner & Other Radio-Related Bulletins Information

RADIO TUNER (AM, FM, ETC.) ONLY PROBLEM DIAGNOSIS/GENERAL INFORMATION:


1. Damaged or defective antennas or antenna cables will affect AM more than FM.

2. Establish a "radio reception test route." Find and record "strong and weak station frequencies." Test all applicable radio complaints on this route on both strong and weak stations. Try to use the same tester on all radio complaints for consistency and familiarity.

3. Electrical interference in the vehicle, from another vehicle, or from external sources, is generally prevalent on AM only. Bad grounds are a common cause of excessive AM noise.

4. AM reception is affected by weather and time of day. It is much better at night.

5 . Certain "noises" are characteristic of FM and cannot be
eliminated. These include:

a. Signal strength fluctuation - caused by driving between tall buildings or hills that intermittently block the signal

b. Weak signal noise - the background noise becomes almost as strong as the weak signal itself

c. Intermodulation distortion - a harmonic of a strong station interferes with a weak station

d. Adjacent channel interference - a strong station of almost the same frequency of the station listened to interferes

e. Multi-path noise - signals reflected off buildings or hills and arrive at the antenna slightly after the direct signal and distort the direct signal

Because these noises vary from area to area, the establishment of a consistently used radio test route will enable you to make valid comparisons between radios.
OTHER RADIO-RELATED BULLETINS:

Listed below are other radio-related bulletins found in the Class 15 section of your binder.

No. SUBJECT

168 Flickering of Digital Display -- J986 Alpine

176 Excessive Ignition Noise on AM, 1988 Gas Sedans
and Wagons

177 Power Antenna Mast Replacement

206 Alpine Anti-Theft Radio

210 Installing 1987 Radio in Previous Year Vehicles

211 Excessive Ignition Noise on AM, All Year Vehicles

212 Anti-Theft Program - Dealer Responsibilities

214 Electric Antenna Maintenance/Diagnosis

229 Intermittent Power Antenna Problems/Power Antenna
Maintenance

239 Hirschmann Power Antenna Failures

262 Out-of-Warranty Radio Repairs 7 Alpine

281 Out-of-Warranty Radio Repairs - All Radios

283 Insufficient AM Signal Strength and/or Excessive
Static in Fringe Areas