am fm car radio antenna trimmer

Mar 27, 2007 4 Replies

does anyone out there know if there is still a way to trim the antenna to the car radio?. I know that i'm showing my age with this statement, but i'm having trouble with the fm stations fading in and out as i travel down the road.i thought that there should be a trimmer somewhere on the radio to tune the stations in stronger. its been a long time since i have worked on radios ,so maybe there is not a way to do it anymore. i have a 95 jeep with am/fm and they both drift in and out.changed the antenna --no help so if anyone out there has an idea i would like to hear from you. thanks dudley



My guess is that the radio is acting up.

My guess is that the FM antenna/radio may be working normally. AM radios used to have a trimmer associated with the high ipmedance/low resistance (very short compared to AM wavelength) antenna. FM antennas are at or near a quarter wave and probably don't have any trimming as the real part of their impedance is pretty large and matching is a bit easier.

Also, it is common for signals to vary with position as fast as once per half/wavelength of distance, which may describe what you are experiencing.

How about comparing with the operation of other FM/antennas moving through the same region, is yours working significantly differently from others? g

A snip from the original post: "am/fm and they both drift in and out"

It has been a while. For AM there should be a trimmer hole somewhere close to where the antenna cable enters the radio. The trick is to tune the radio to a very weak station at low end of the band, somewhere between 550 and 600 KHz. Adjust the trimmer to best reception for that.

Boris Mohar

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