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  #1  
Old 11-26-2009, 07:16 AM
andrefranc andrefranc is offline
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Static as you dial

I get lots of static just as I turn the dial and when I stop turning the dial the static stops. What could cause this? Radio seems to work fine otherwise.
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  #2  
Old 11-26-2009, 10:46 AM
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electroking electroking is offline
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Intermittent short in the variable capacitor is likely. By the way, the following trick
will let you know if the local oscillator is working (assuming you have a
superheterodyne radio).

Set a good working AM radio to a quiet spot near the top of the frequency range.
Bring the radio to be tested close to the working radio. Now slowly rotate the
tuning knob of the radio under test. As you pass the point where the local
oscillator is running at the frequency of the working radio, you will hear some
kind of interference. For instance, if the radio under test has an intermediate
frequency of 455 kHz, and the working radio is set to 1400 kHz, the radio
under test will oscillate at the latter frequency when tuned to 945 kHz.
Good luck.

Last edited by electroking; 11-26-2009 at 10:46 AM. Reason: corrected typo
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  #3  
Old 11-26-2009, 11:22 AM
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jpdylon jpdylon is offline
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if the static is only audible on the FM band (assuming this has one) then the problem can sometimes be the brass or copper ground couplers that rest against the tuning capacitor shaft right where the shaft passes through the bearing. The contact becomes intermittent due to corrosion on the contact point - which can be easily cleaned and remidied through the use of a teflon lubricant like zep45. Only use a drop or two on each contact point and work the tuner back and forth.

If its only on the am band and or part of the FM band doesn't work then I would suspect a short as mentioned above.

Good luck.
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Old 11-26-2009, 03:32 PM
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electroking electroking is offline
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Of course I assumed you had an AM radio!

But my oscillator test also works with FM radios, the IF is 10.7 MHz. For instance
if you set a receiver to 105 MHz, it will get interference from another one tuned at
94.3 MHz.
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  #5  
Old 12-05-2009, 05:52 AM
Dude111 Dude111 is offline
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It could be a dirty knob...

On one of the older radios i used to have the same thing happend.. (It was all dirty right inside the cover and when the knob was turned,you heard crackling sounds)
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Old 12-05-2009, 06:57 PM
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Reece Reece is offline
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Probably dirty tuning capacitor, as others mentioned. Put a couple of drops (don't soak with spray) of WD-40 on the brass springs that contact the rotating shaft and work dial back and forth. Spray a little WD in a bottle cap and apply with a toothpick or cotton swab. If the front bearing is ball bearings, toothpick a little white grease in there. If it continues, blow out the plates with computer keyboard air. If noise continues, sign in again.
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Old 12-12-2009, 05:39 PM
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sanford12 sanford12 is offline
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The blades of the tuning capacitor might be dirty or touching causing the same type of symptom.
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