last year found a 70 am radio for my chevelle, had it installed and played good for a few days than the reception went south on all the stations. checked everything still no good. i had a new windshield put on still no better.It actually got worse. i was told get an fm for better reception. I found a nice am/fm mono and had it installed today, played great boy was i happy and all the fm stations were perfect. drove about 15 minutes and the stations went south..which drove ne #####crazy. i checked all the things i could think of and still no good. any idea what to do and why would it get perfect reception and than die??? please help me.

By saying "all the stations went south", do you mean an increase in static, loss of volume, more background noise? A little more info might lead to a solution. Where in NJ are you?

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MalibuJerry350
TC Member #1279
Original owner '70 Chevelle.
560,000+ miles on car.
Hey, if it's got wheels, DRIVE IT!
My Chevelle: http://hometown.aol.com/erie614/myhomepage/index.html

I am definitely no expert here but I did watch Coppertop, (he used to post here a lot), as he set the "trim" on my antenna.

With the radio installed, pull off the right side knob and tone control hub. Look closely at the stem sticking out and you'll see a tiny hole in the dash just above where the stem comes through the dash. (It's normally hidden by the tone control hub). I don't THINK we had to take the nut off the stem. With a small jewelers size screw driver you can turn the trim adjustment screw back and forth to set the trim. When the reception sounds best... you're done. Helps to tune in a weak station to set it. I don't know if this will help your situation, but it's worth a try.

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Bob Von Kaenel
70 SS 402ci TH400

Considering the fact that the radio plays normally for awhile, the antenna trim adjustment wouldn't be on my list of suspects. One thing to check, for sure, would be the antenna lead from the radio to the windshield bulkhead connector. Also, be sure that the connector on the outside of the cowl where the "pigtail" from the windshield antenna plugs into, is clean and free from all debris and corrosion. if you're close enough to me, I can take a peek and try to help you out. (I owned a TV/Radio repair shop for 20 years).

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MalibuJerry350
TC Member #1279
Original owner '70 Chevelle.
560,000+ miles on car.
Hey, if it's got wheels, DRIVE IT!
My Chevelle: http://hometown.aol.com/erie614/myhomepage/index.html

NO, I JUST LOST THE RECEPTION ON ALMOST ALL THE FM STATIONS...NEW STOCK WIRES,POINTS DIST...NO STATIC...RADIO WAS PLAYING PERFECT FOR ABOUT 15 MINS OF DRIVING...THEN LOST ALL RECEPTION...I CHECKED ALL WIRES COMING FROM THE NEW WINDSHIELD INTO THE RADIO CLEANED THEM ENEN THOUGH THETY LOOKED FINE. THE THING THAT GETS ME IS THAT THE RADIO AND RECEPTION WAS PERFECT FOR ABOUT 15 MINUTES OF DRIVING AND THAN THE RECEPTION WENT TERRIBLE ON ALL THE STATIONS.THANKS FOR EVERYONE REPLS...

What Ohm speakers are you using. Most newer speakers are 3-4 ohms, while the older speaker were 8 - 10 ohms. These old radio's do not like to be run on the newer 3-4 ohm speakers. Not sure if this is your problem but it could be something to consider.

I'm not sure on the ohms. The speaker was replaced year when I had a 70 am delco installed. I'll have to check. Thanks

ok....so how important is it to have the correct ohms 8-10 versus 2-4. my speaker is the 2-4 ohm and did you ever try to buy one????good luck. does it really make sense that the wrong ohm's could interfere with the reception???

okay my turn...

First off, you are severly shortening the working life of radio by using "2-4" ohm speakers!!! I always preach (as it says on the speakers section of Radio Tech), do NOT use anything less than 8 ohm speakers!!! The factory units were 10 ohms. Yes, 8 ohms are hard to find, so get (2) 3-4 ohm units and wire them in series! For example,By using a single 3 ohm unit, the poor audio output transitor (which is an $$$ obsolete style) is having to carry 3X the usual current. You're going to fry the output transistor, and probably blow up the emitter "fusistor".


Reception has nothing to do with speaker impedance.

So are you saying you lost everything??? NO AM EITHER???

Here's what you do, take a long piece of scrap wire with the end stripped, or bend an old coat hanger and stick it into the antenna jack of the radio. Completely rule out the factory antenna this way. Turn the key to the "ACC" accessory position so the radio operates. Tune to the STRONGEST LOCAL AM and FM stations--do you get anything???? IF NO, your radio took a crap, could be solder joint, FM decoder IC, etc etc etc... that would require a technician to repair. If the old jury rigged antenna makes it come to life, you've got factory antenna problems.

Let us know.

[This message has been edited by Coppertop (edited 09-24-2001).]

well picked up a new 8ohm speaker installed it and I sent the radio back down to have the seller look at it and advise me what went on it.....I'll keep you informed and as usual thanks for everyones help!

Is it possible the antenna plug is not very tight, and after a little driving it comes loose/off?

I have an aftermarket (Alpine) unit in my 1971. After market speakers. All connections appear to be good and I have the same problem. The FM worked great for about 3 days, then has faded so I can't pick up any stations. Touching the radio chassis improves reception, so I am thinking it is a ground problem. Any suggestions/hints?

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1971 El Camino
SB350/TH350
12 bolt posi

I wish it was that easy. No everything was
connected real good......now like the prior post would a ground possible problem cause the radio to lose reception after playing for a while???