Got my replacement AM thumbwheel radio installed today!

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gossame1

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Hello Gang,

Just a quick note to say that I had my AM thumbwheel radio (Original refurbished) installed today at the local Chrysler dealer. While the technician was under the dash installing the radio, he happened to notice that the speaker was deteriorated and possibly caused the old radio to go bad. I need to do some fine tuning and I should be set to go. My shop manual says that the radio should be 'trimmed" How do I do this and is this a major operation? The reception seems a little weak at times compared to the radio which I replaced before this one. Thanks again for everybody's help and input so far!

Keep in touch!

Brian Carotenuto
 
I have never heard of trimming a radio?? The speaker did not cause the radio to go bad. I wouldn't worry about it. Good luck
 
Just alittle tip. i replaced the stock in dash speaker with a pair of 3" speakers. I took the old speaker out, removed the mounting ring and screwwed the pair of 3" speakers to that. Then put it in the dash. Better sound and no one will know its their. :wink:
 
Good tip Fastback. I think I'll try that on mine. I'm sure after 33 years it pretty much shot anyway and the two three inchers should improve the sound.
 
Improve the sound of an AM radio? Yeah, right. Maybe the tone will change a tad due to the smaller cone diameter.

Be carefull how you wire two speakers to a single channel radio. If they are 4ohm speakers, as most common replacements are, then you should wire them in series. This means the wire out of the radio goes to the + terminal of speaker A. The - terminal of speaker A goes to the + terminal of speaker B. And finally, the - terminal of speaker B goes to chassis ground. This ADDS the the two speakers impedence so that the radio sees 8ohms. If you wire them in parallel, then the impedence would be 2ohms and you could burn up the output transister of the radio.

As for 'trimming' a radio, this is matching the the tuner impedence to the antannea. I picked op a Music Master AM for my Dart a few months ago. I haven't installed it yet because I have to fix the hole in the dash. Anyway, I can see it has some holes in the back whare you can access some trim pots. I don't know the exact procedure for these radios, but I assume you would try tuning in a local station as best you can with the tuner knob. Then try 'tweaking' the trim pots a little at a time to see if the signal strength gets better. If you attempt this, make sure you keep track of the original position so you can return to it. You don't want to make it worse than what you started with.
 
good call. I didnt have the stock radio in my car when I did that. :wink:
 
Yea, and I have an AM/FM in mine now. I agree, the AM only is a lost cause.
 
I just learned that AM radios have a set screw in the front under one of the knobs. I had a slotted hole in my Duster for this screw. (Don't remeber which knob it was under) You take a small slotted screw driver and change the setting on the antennae. It is called "trimming" the antennae. I will make your signal come in weaker or stronger depending on how you trim your antennae. :|
 
Is that only on the AM model or would the AM/FM radio also have the trim feature. I have a 1973 model AM/FM in mine now, instead of the R11 version it came with.
 
I also have an AM/FM thumbwheel radio for my 68 Dart. The guy that rebuilt it showed me the small screw in the front of the radio. He said I needed to tune the antennae. I just turned the screw about 1/2 turn both ways to get it to have maximum sound. :knob:
 
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