Radio doesn't get good signal - Team Camaro Tech
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post #1 of 15 (permalink) Old Oct 2nd, 07, 06:34 PM Thread Starter
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Patrick
 
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Radio doesn't get good signal

I have a brand new Alpine cd player, costs $150 new so it isn't "top of the line" and it won't pick up hardly any station without static in it! Brand new antenna and it is plugged in. Is it the radio? What else could it be?

69RS/SS,383,10:1cr,4.10,60ft1.6sec,1/[email protected],1/[email protected],Vicjr,RPMheads,750dp, Proform main body, cam,246*-250*@.050,.510,522,1.6rr,700r4,3200stall
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post #2 of 15 (permalink) Old Oct 2nd, 07, 07:04 PM
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Charlie
 
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Re: Radio doesn't get good signal

Are you sure it has a good ground? I have an Alpine and it gets great reception. Make sure the antenna isn't broken at the body. Perhaps it got damaged when it was installed. Just a thought. Other than that I don't know. If the antenna is in good condition and it's grounded correctly, then the radio may have an internal issue. I have seen them have problems even when new. Electronics are tempermental. They also make antenna signal boosters. Radio Shack sells them.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #3 of 15 (permalink) Old Oct 2nd, 07, 07:24 PM Thread Starter
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Patrick
 
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Re: Radio doesn't get good signal

Thanks, I will check the ground. I do have a new paint job so this might be where it's not grounding good.

69RS/SS,383,10:1cr,4.10,60ft1.6sec,1/[email protected],1/[email protected],Vicjr,RPMheads,750dp, Proform main body, cam,246*-250*@.050,.510,522,1.6rr,700r4,3200stall
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post #4 of 15 (permalink) Old Oct 2nd, 07, 07:36 PM
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Re: Radio doesn't get good signal

Unplug the coax from the radio and do a continuity check between ground and the shield connection of the coax. Also check the center conductor to the whip. And finally, check to make sure the center conductor and the shield are not shorted together.

If the coax itself gets crimped it can affect signal strength. Also, strong noise sources, such as ignition noise, can swamp the RF stage and desensitize the radio. Usually signal swamping can be ruled out by operating the radio with the car off.

Radios have steadily degraded over the years. Manfacturers are moving toward cheap integrated receiver stages and some of them, quite frankly, suck. Also, even the cheaper receivers have to be properly "aligned" which requires special test equipment. Sometimes the QC folks get it wrong. Hopefully quality isn't the issue with yours and one of the above fixes will get you going again.

Dave
========================
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post #5 of 15 (permalink) Old Oct 2nd, 07, 09:02 PM
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Kevin
 
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Re: Radio doesn't get good signal

Quote:
Originally Posted by 67CamaroRS/SS View Post
They also make antenna signal boosters. Radio Shack sells them.
I would caution against going this ^ route. If you don't isolate/eliminate the noise to begin with, all a signal booster will do is strengthen the noise level . It's a common mistake people make to try to fix a noisy signal. They only help with a weak signal.

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69' - Built 350, 750 Holley, Elgin E920P Cam, 283 PP Heads, Long Comp Headers, MSD, TKO-600, 12 Bolt Posi 3.73, Hotchkis Rear, Eibach Front w/Hotchkis Sway, SPC UCAs, 3rd Gen PS, AR TTII's. Still working on it.
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post #6 of 15 (permalink) Old Oct 3rd, 07, 04:38 AM
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Re: Radio doesn't get good signal

Lots of good suggestions given, good ground at the unit and good antenna ground and a good RF cable are needed for good reception. Also, correct construction/assembly of parts.

A quick troubleshooting technique for antenna ground is have the radio playing, then touch the antenna mast. If volume goes up, antenna needs better grounding.

The antenna is grounded on the bottom side of the body panel, whether front fender or rear pass qtr mounted. Make sure the panel is clean. Lube area with petro jelly to prevent rusting.

Radios have come a long way - tubes to transistors to IC (intergrated circuits) to an all-in-one processor.

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post #7 of 15 (permalink) Old Oct 3rd, 07, 08:00 AM
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Re: Radio doesn't get good signal

I read it as he has static, which is from a weak signal. I could see if he said he had a buzz or whine in the speakers, but he can't even get a station to come in to hear the buzz. I agree if he has alternator noise or something along those lines, then no, do not install a signal booster, but he is experiencing a weak or no signal. In this case a signal booster would be a benefit.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #8 of 15 (permalink) Old Oct 3rd, 07, 10:42 AM
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Re: Radio doesn't get good signal

Quote:
Originally Posted by 67CamaroRS/SS View Post
I read it as he has static, which is from a weak signal. I could see if he said he had a buzz or whine in the speakers, but he can't even get a station to come in to hear the buzz. I agree if he has alternator noise or something along those lines, then no, do not install a signal booster, but he is experiencing a weak or no signal. In this case a signal booster would be a benefit.
Weak signal is a relative term when talking about FM. Essitially it means the signal is not significantly above the noise floor to detect it. So either the signal is weak or the noise floor is so high that the receiver can't distinquish it from the mud. With FM, things like ignition noise and alternator noise can affect the signal without actually sounding like it would on AM. This is because the RF stages get overloaded with noise and become less sensative to the weak signal you're trying to reach.

Dave
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post #9 of 15 (permalink) Old Oct 3rd, 07, 11:21 AM
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Re: Radio doesn't get good signal

I am leaning towards the antenna being bad. You would be surprised at how small/short of an antenna you actually need to be able to pick up the FM band. I have successfully received an FM signal with an antenna as short as 1 1/2". AM on the other hand is a different beast. You would need your antenna fully extended to receive AM. Antennas do not cost that much. I would suggest trying another antenna. It is very possible that it was defective or got damaged during shipping. The fact that it, according to you, will pick up some stations, even if not fully says that the radio is functioning as far as the antenna goes. The radio doesn't actually amplify the signal. It's basically only a receiver.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #10 of 15 (permalink) Old Oct 3rd, 07, 03:46 PM
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Re: Radio doesn't get good signal

Quote:
Originally Posted by 67CamaroRS/SS View Post
The radio doesn't actually amplify the signal. It's basically only a receiver.
Sorry to pick nits, but the radio doesn't only amplify the signal it amplifies the entire radio spectrum and selects the channel you're after. That's exactly why other noise sources can swamp the RF stage and desense the receiver. A radio with low noise amplification stages is crucial to good performance. Amplification is a huge part of how it works. If it weren't for amplification, we wouldn't have radios at all. (Of course there are those cat-wisker radios with wire wrapped around an oat-meal can. But those required a strong signal to begin with and barely produced a whisper)

I think what you're trying to say is that getting a good signal starts with the antenna and I completely agree.

As for the length of the antenna, it depends on a lot of factors. A 1 and 1/2" antenna may work but I'm sure the automatic gain control in the RF section was maxed out trying to amplify the signal. Funny thing about FM is if the receiver can capture the signal, it's relatively noise free. A radio works best when the antenna is at least 1/4 wavelength long at the frequency you're receiving (about 2.5' long at 100Mhz).

Dave
========================
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post #11 of 15 (permalink) Old Oct 3rd, 07, 04:35 PM
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Re: Radio doesn't get good signal

I don't agree with that about the antenna at all. The FM signal can be picked up by an antenna that is almost completely distended. An antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. In other words, antennas convert radio frequency electrical currents into electromagnetic waves and vice versa. The radio transforms these electromagnetic waves into sound or other signale that carry information.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #12 of 15 (permalink) Old Oct 3rd, 07, 04:50 PM
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Re: Radio doesn't get good signal

LOL. I'll let you guys argue about all that. But for what it's worth, Charlie, I wasn't saying you were giving bad advice. I was merely pointing out that he needed to be careful determining what his needs are before running to buy a booster.

Learning & Relearning about the cars I grew up with.
69' - Built 350, 750 Holley, Elgin E920P Cam, 283 PP Heads, Long Comp Headers, MSD, TKO-600, 12 Bolt Posi 3.73, Hotchkis Rear, Eibach Front w/Hotchkis Sway, SPC UCAs, 3rd Gen PS, AR TTII's. Still working on it.
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post #13 of 15 (permalink) Old Oct 4th, 07, 08:26 PM
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Re: Radio doesn't get good signal

Actually if you put every thing together that has been offered up by every one you have the jist of it. The fm signal is a wave that the antena converts to a weak electical signal which is sent to the radio (reciever) and the radio demodulates the signal and sends the signal to the speakers where it is turned into acoustical energy. The reason fm has less noise than am is because fm uses limiter circuits to delete amplitude variations in the signal before it is processed by the radio. How ever you can get noise through the harness itself or from rfi interference in the speaker wires as well as the antena. It is very crucial to have a good ground for the system as was stated before. Putting a new ground from the radio case to a known good ground is a very good idea. If there is already a ground and it could be questionable, make sure that ground is unhooked and your known good ground is the only one hooked up. Failure to disconnect a possible bad ground could result in a ground loop, and distort the signal. But the antena and radio has to have a good ground plane in order to fuction properly.

And that concludes the lesson for today. lol

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post #14 of 15 (permalink) Old Oct 6th, 07, 01:00 PM Thread Starter
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Patrick
 
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Re: Radio doesn't get good signal

Ok guys I have found and fixed the "static" problem. Charlie you were right, the antenna on the fender was not getting a good ground. I scrubbed with sand paper underneath and it is now crystal clear! Thanks everyone for the suggestions, yall saved me a lot of $$$!!

69RS/SS,383,10:1cr,4.10,60ft1.6sec,1/[email protected],1/[email protected],Vicjr,RPMheads,750dp, Proform main body, cam,246*-250*@.050,.510,522,1.6rr,700r4,3200stall
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post #15 of 15 (permalink) Old Oct 6th, 07, 06:11 PM
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Re: Radio doesn't get good signal

Right on. Thanks for posting back.

Dave
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