SDS200 Odd Noise

[W5ATX]

No it's not related to the hum mitigation, this one is different. when you turn the unit on, after about 10 minutes there's a super high pitch squeal, about 14kHz and it slowly sweeps down to about 10-12k after a minute then disappears, then a few minutes later it's audible for another minute, continues sweeping and then fades away. the best way to explain it is it's similar to the sound an old tube TV makes when you first turn it on, the super high pitch sound you hear. It is only audible when the unit is receiving a signal, and is not volume dependent, i.e. the volume can be on zero and you can still hear it thru the speaker. I tried to record it with my phone which has a wide frequency range mic but it's hard to hear and doubt you'd be able to hear it unless you had supersonic hearing with drivers that could reproduce it on your end Anyone else with an sds200 ever hear something like this? It's not worth sending to uniden at this time, but maybe uniden has heard a few other reports such as mine and knows what the solution is. Thanks guys.

 

[dave3825]

Does anything display on the screen when this happens?

 

[W5ATX]

Hi dave, yes everything works as normal, i have even toggled thru the screen intensity and turned the screen off and the sound is still there. it sounds like a cap may be out of tolerance in the audio circuit or similar. it's easier heard on a hi-fi external speaker. but it's also heard on the internal speaker (barely). the external speaker i'm using is an optimus pro X7 which has a freq range of 100Hz-20kHz and an impedance of 8 ohms. I've got another sds200 in the shack with the same speaker and no issues so it's in the scanner.

 

[donc13]

Hi dave, yes everything works as normal, i have even toggled thru the screen intensity and turned the screen off and the sound is still there. it sounds like a cap may be out of tolerance in the audio circuit or similar. it's easier heard on a hi-fi external speaker. but it's also heard on the internal speaker (barely). the external speaker i'm using is an optimus pro X7 which has a freq range of 100Hz-20kHz and an impedance of 8 ohms. I've got another sds200 in the shack with the same speaker and no issues so it's in the scanner.

You said the noise is only there when receiving a signal. Is the system, department and site always the same? Do you hear any station audio at the same time?

Are the filters (global or site specific), ifx, etc set the same on both sds200s?

 

[W5ATX]

noise is there only when receiving a signal, departments are different, site is the same simulcast freq, filter is off. i have 2 sds200's scanning similar stuff, same external speakers, this one makes the noise for a few minutes about 5-10 minutes after turn on, after that it's quiet.

 

[tvengr]

i have 2 sds200's scanning similar stuff, same external speakers,

Did you try swapping the two speakers between scanners?

 

[Ubbe]

It is only audible when the unit is receiving a signal, and is not volume dependent

Try setting the Audio Off Time to Infinite as it is its mute function that stops the squealing in the audio power amplifier.

Check that it isn't the power supply that creates this problem as it probably are more or less directly connected to the speaker amplifier.

/Ubbe

 

[RandyKuff]

If you can, try running it off a 12 volt battery with the vehicle harness... If it goes away then the wall wart is the problem...
If still there, it's something internal to the radio...

 

[W5ATX]

all great suggestions, i'll have to try this over time, as it only does it when the scanner sits over night and is turned on cold in the morning.

 

[tvengr]

Since it only occurs when turning the scanner on, try reseating the SD card. The scanner reads from the card when you turn it on.

 

[werinshades]

How long have you owned it? If it's within a year, I wouldn't mess around with anything and send it in for repair. I own 4 of them, and never had this issue. Something isn't right.

 

[W5ATX]

this one is about 2 years old, i'm the original owner, but sold it to a friend, he's now silent key so i bought it back from the family. , never noticed this noise before, it's so faint, and only makes it when the scanner is cold and about 5 minutes after turn on. remember the old electronic flash modules on a camera? when you take a picture, you can hear the high voltage charging the caps back up, and a few seconds later the light turns green indication it's ready for another photo? it's like that, but the tone descends and it's very faint, and a lot slower.

 

[werinshades]

this one is about 2 years old, i'm the original owner, but sold it to a friend, he's now silent key so i bought it back from the family. , never noticed this noise before, it's so faint, and only makes it when the scanner is cold and about 5 minutes after turn on. remember the old electronic flash modules on a camera? when you take a picture, you can hear the high voltage charging the caps back up, and a few seconds later the light turns green indication it's ready for another photo? it's like that, but the tone descends and it's very faint, and a lot slower.

Yes, I remember those cameras which shows my age a bit. You mentioned before it's not the dreaded hum, and don't recall anyone else mentioning this, so this is why I would send it in and have them check.

 

[W5ATX]

i'll ride this one out, just curious if anyone else has had this particular issue. It's so subtle one may not notice it. I did my own hum mitigation via scraping one of the screw terminals and hum is 90% gone, but this is a new noise. uniden may or may not honor the $90 repair fee but it's out of warranty anyways. no worries, i'll drive it till the wheels fall off this is my 6th sds i've purchased, i've sold a few and still have 3 left.

 

[JoeBearcat]

I've heard similar noises (on devices other than scanners). It usually comes down to a ground loop issue.