Bob's Component Resto Part 11: The Radio

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cruiser

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Good evening Mopar faithful! I hope that you enjoyed Part 10, the brake master cylinder resto. Hopefully, tonight's installment will put you in the mood for a nice long nap. Like many Chrysler products back in the day, my 1974 Duster came with the code R11 Music Master two watt AM radio feeding a single in-dash speaker. As in most any 47 year old used vehicle, the radio in my car no longer worked when I bought the car in 2019. And since I was determined to restore my Duster as stock as possible, I decided to restore the sound system that I had instead of upgrading it to a modern multi mode system. The first step was to remove the radio, whereupon I noticed that the support bracket that held up the rear of the radio was missing. In any case, out came the radio along with the original 4 x 10 speaker in the dash. I'm quite certain that the radio is original to the car (see the photo of the data tag from the top of the radio) and that the speaker is the factory unit as well. The photo of the data tag on top of the radio contains the date code of 1903, which denotes the 190th day of 1973 - which is correct for my car that was built in October of 1973. I sent the radio to S&M Electro-Tech in Blaine MN where they removed and replaced several faulty electrolytic capacitors and the #1893 dial illumination bulb. They also checked the alignment of the tuner mechanism, then lubricated it for smoother operation, cleaned up the tuning dial and bench tested it. At the same time I sent the speaker to Heavy Sound in Venice CA for overhaul. There they re-coned it, replaced the voice coil, replaced the torn fabric over the cone and bench tested it as well. The only other component of the system was the antenna. I'm not sure if the antenna that came with the car is the factory original one. The car came with a lot of paperwork, including a sheet entitled "Manual Antenna Installation Instructions". The antenna is the correct one for my Duster, however, and works perfectly. When everything came back, I installed the speaker and radio (with a replacement support bracket from the salvage yard), hooked up the antenna and fired it up. And for the first time in many years I had high quality AM sound coming out of my dash! I let it warm up for fifteen minutes and then adjusted the radio to 1400 khz. I then "trimmed" the radio with the trimming screw under the tuning knob. This serves to perfectly match the frequency of the radio to the resistance of the antenna, producing the optimal sound from the system. The radio is pretty primitive, of course. It has a volume knob with a tone control ring underneath it on the left side, and a tuning knob on the right. I must say however that I love the retro feel of the whole thing. It has five presetting buttons which I set to my favorite stations in Minneapolis. The old school tuning knob is great for pulling in dim and distant stations. I've noticed how few AM music stations there are any more. Most AM programming seems to be either religious or Spanish speaking. My favorite oldies station is WDGY - "740 on your AM dial" - here in Minneapolis. WDGY (then at 1130 khz) was Minneapolis' dominant AM music station back in the 1960s. Picture this fellow Moparites: A lovely afternoon enjoying the fall colors on a Minnesota country road, the slant six motor up front purring like a sewing machine, the windows down but the heater on to take the cool edge off, and the radio playing the Chicago's "Wishing You Were Here". If that isn't motoring heaven, I don't know what is. So that's it for tonight's chapter. I know that you're sleepy by now, so have that lovely image in mind as you drift off tonight. Be well my friends. Night night!

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How do you "adjust to 1400 khz, and then trim it with the trim screw"? Do you need a special meter etc? Thanks
 
So, you set the dial at 1400 then adjust the volume of the static?

No, you hook everything up, then tune to 1400 even if there is no station there. Set the volume knob so you can hear the station or static well, then leave the volume knob alone.

The "trim screw" is under the face plate. Turn it back and forth and the volume will go up and down. Leave it where the volume is loudest. What you are doing is matching the antenna to the radio. This is very old-school stuff.
 
Are your photos before or after?
The photo of the top of the speaker is a "before" photo. Note the detached and wrinkled speaker fabric on top. The rest of the photos, including the photo of the car itself, are "after". Thanks - cruiser
 
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How do you "adjust to 1400 khz, and then trim it with the trim screw"? Do you need a special meter etc? Thanks
Even though it's not visible in the first photo, the trimmer screw is under the tuning knob on the right side. This screw uses a small flat bladed screwdriver to adjust. Really simple.
 
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