Pro-106 hum when charging in car and listening via radio

[tomas21]

Setup: Pro-106
Plugging into USA-SPEC PA15 HON2

When I listen without the scanner being charged via Radio shack 9-v adapter I hear no hum. Once I plug in the charger to the scanner the hum is loud. Any recommendations?

I have tried the PAC's SNI-1/3.5 but that didn't seem to help much. I have heard radio shack makes a decent one but wanted to get some input.

 

[OsloViking1975]

I have a enercell 9V 800mA adapter. Must buy the Adapt a plug (C) for it . I bought this from RS. I have hear no humming sound.

For in the car charger I have a RS 273-1863 Fuseless DC-DC Adapter IN:12VDC OUT:9V 1A this also works with the Adapt a plug (C). I have had this for quite some time and have had no problems.


This is the newer version of the one I have. http://www.radioshack.com/product/index.jsp?productId=3812864 $22.99 at RS. made by enercell

If you choose to buy this I would suggest to go RS with your scanner and make sure you get the right adapt a plug that fits your scanner. RS list Q, O, and N for
the above mentioned.

KCEIB would no. I'm sure he can guide you the right direction. He usually pos up here in the RS scanner forum.

 

[RadioDaze]

Do you have anything else plugged into the scanner besides the charger? If you have a ground to the scanner coming from 2 different point, you could be getting a "ground loop"

 

[OsloViking1975]

As Radio Daze mentioned ground loop is possible.

 

[N8IAA]

First, charging your batteries in the unit is not neccessarily a good idea for radio and personal health Second, if you have a cable from the speaker jack to a jack in the vehicle radio, and have the cigarette dc-dc adapter plugged in, you will have a ground loop. You will need to ground the radio somehow, being that it is plastic, it may be hard to do. Best option, not charge the batts while using the car adapter.
HTH,
Larry

 

[OsloViking1975]

I have a enercell 9V 800mA adapter. Must buy the Adapt a plug (C) for it . I bought this from RS. I have hear no humming sound.

For in the car charger I have a RS 273-1863 Fuseless DC-DC Adapter IN:12VDC OUT:9V 1A this also works with the Adapt a plug (C). I have had this for quite some time and have had no problems.


This is the newer version of the one I have. Enercell 9-Volt 1000mA Vehicle DC Adapter : Car Adapters | RadioShack.com $22.99 at RS. made by enercell

If you choose to buy this I would suggest to go RS with your scanner and make sure you get the right adapt a plug that fits your scanner. RS list Q, O, and N for
the above mentioned.

KCEIB would no. I'm sure he can guide you the right direction. He usually pos up here in the RS scanner forum.

meant to write know.

 

[tomas21]

Well it sounds like i definitely have a ground loop. Curious to hear what KCEIB has to say.

 

[KC5EIB]

Setup: Pro-106
Plugging into USA-SPEC PA15 HON2

When I listen without the scanner being charged via Radio shack 9-v adapter I hear no hum. Once I plug in the charger to the scanner the hum is loud. Any recommendations?

I have tried the PAC's SNI-1/3.5 but that didn't seem to help much. I have heard radio shack makes a decent one but wanted to get some input.

Questions:

Operating the scanner while powered from a 12v to 9v car adapter, no hum but when running off a home adapter (120v to 9v) adapter you have hum?

Are you using an external speaker or are you hearing the hum on the enternal speaker?

 

[KC5EIB]

.

I have a enercell 9V 800mA adapter. Must buy the Adapt a plug (C) for it . I bought this from RS. I have hear no humming sound.

For in the car charger I have a RS 273-1863 Fuseless DC-DC Adapter IN:12VDC OUT:9V 1A this also works with the Adapt a plug (C). I have had this for quite some time and have had no problems.

The currenf adapters are switching type (no transformer) and the home charger is 2730314 while the car version is 2730369. Ger the adaptplug tip "B" which fits better then the "C" tip, which comes free, with either power supply.

 

[tomas21]

Questions:

Operating the scanner while powered from a 12v to 9v car adapter, no hum but when running off a home adapter (120v to 9v) adapter you have hum?

Are you using an external speaker or are you hearing the hum on the enternal speaker?

- Scanner connected to home 120v to 9v adapter no hum
- Scanner connected to to car 12v to 9v adapter + headphone jack on scanner plugged into car stereo there is a hum.

- Hum in car stereo since scanner headphone jack is connected to it. My scanner is actually connected to the rca's of my USA-Spec device which in turn is connected to my car stereo. It works great when 12v to 9v isn't connected but once I connect/charge my scanner the hum becomes an issue.

Pic of USA-Spec Unit

 

[KC5EIB]

As others have said, sounds like a ground loop. One way to fix it is to make a cable using the 2731380 audio output transformer as an issolation transformer. Wire the 8 ohm side to the plug for the scanner and the other side to the RCA connectors using the Black as ground for both sides and the Blue and Green leads for the signal leads.

 

[madhatter66]

I get the same hum out of my 164 using the 9v 800 mA charger from RS plugged into 120v... I tend to get some signal loss, and a hum when its plugged in at night... I just attributed it to running electricity through a sensitive receiver...

 

[KC5EIB]

I get the same hum out of my 164 using the 9v 800 mA charger from RS plugged into 120v... I tend to get some signal loss, and a hum when its plugged in at night... I just attributed it to running electricity through a sensitive receiver...

In your case, that would be correct along with the fact that just about every power supply on the consumer market has some AC ripple on the output which is easy to see on a scope.

The issue that tomas21 is having comes from direct connected audio outputs to high gain amps where the grounds are at different electrical levels. One or both units can, and most likely do, have grounds in the audio circuits that are not connected directly to chassis ground which will cause the hum to appear.

 

[DickH]

Setup: Pro-106
Plugging into USA-SPEC PA15 HON2
... Once I plug in the charger to the scanner the hum is loud. Any recommendations?
.

Your car must be a Hummer.

 

[RadioDaze]

Bummer...