| Author |
Message |
    
THE GOAT (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, December 19, 2004 - 12:48 pm: | 
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Does anyone know what causes a hum when the volume is turned down. Or the squelch is up. There is a Annoying hum Anybody know what to change. |
That Elco guy (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, December 19, 2004 - 1:14 pm: |
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You did not say if the install was in the home or not. But in general a hummmmmm when using an external power supply is caused by an "UNREGULATED" power supply or a defective regulated power supply that is allowing ripple to take place.
Ripple is when you have a single diode that converts ac to dc on half of the ac cycle and just blocks the ac on the other half. You get this constant off-on effect in the DC after the diode rectifier.
Ripple on a regulated power supply is caused by a diode on the bridge rectifier being blown causing a ripple effect in the output of the rectifier or the filter electrolytic caps going bad and not properly smoothing out the minor ripples.
An unregulated power supply has ripple causing hummmmmm because there are no caps to filter out the ripple that remains after recification.
The sure way to tell is to put the radio on the car battery while the engine is NOT runnung. IF the humm suddenly vanishes then its your power supply--get NEW one, a regulated one.
Sometimes HUMMMM comes from florescent lights as well. You might want to track down that possibility as well.
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Bruce
Senior Member
Username: Bruce
Post Number: 1900
Registered: 9-2003
| | Posted on Sunday, December 19, 2004 - 2:06 pm: |
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i agree unless he has lost a ground in the radio the power supply is the only other source |
The Goat (Unregistered Guest)
Unregistered guest
| | Posted on Sunday, December 19, 2004 - 3:46 pm: |
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The powersupply is fine. I am using it on a base. My voyage 9000 has no humm but this one does. When there is no coax in the radio there is no hum right when i plug the coax in the radio it starts that little hum |
Bruce
Senior Member
Username: Bruce
Post Number: 1904
Registered: 9-2003
| | Posted on Monday, December 20, 2004 - 7:27 am: |
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hummm i smell some strange ground loop .... |
that ELCO Guy (Unregistered Guest)
Unregistered guest
| | Posted on Monday, December 20, 2004 - 8:21 am: |
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I agree with Bruce. IF the warranty is voided/expied open up the case and without damaging anything closely examine with a magnifying glass all the solder joints. Examine all the places where the screws attaching the board come into contact with the radio board--look for loose screws and corosion. Look for wires that are loose in solder joints/cold solder joints. Look at the components to see if any of them are burnt in appearance that should NOT be burnt in appearance.
If that fails well ONCE I had a board in my Yaesu FT 101E that would cause a humm because the contacts on the connection of the board got dirty. Every once and a while I would have to take it out and clean the contacts--problem solved. If your radio has dirt or grime on the boards clean the boards (properly) with the proper board cleaner--ask your local radio tech what to get.
If this does not solve the problem then take thee to the radio tech for their expert services.
Later
That ELCO Guy.
PS Seasons best to you Mr Bruce. |
