SDS-200 hum, no hum, ho hum

vanhalo

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I received my SDS-200 on 7/1/2020...and it has been scanning frequencies since that day using the stock antenna for the most part.
I move it around quite a bit.
Today i was listening to it in my upstairs living room and noticed "the hum" (using stock antenna )
Never heard it before.
I moved it back down to my office where i run it from a 12v cigar adapter to a 40ah Lithium battery.(using Scanner Master SpectrumForce Wideband Antenna)
No hum.

So i am not sure if I have the "hum" issue or if I am just experiencing some new interference upstairs.
 

tvengr

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Unless you have a higher noise level in your office to mask the hum, I would suspect you have ripple voltage on your AC adapter used in the living room. The display induced hum is independent of the power supply. The fact that you do not hear the hum while on battery power in your office leads me to suspect you have a bad AC adapter upstairs.
 

vanhalo

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Unless you have a higher noise level in your office to mask the hum, I would suspect you have ripple voltage on your AC adapter used in the living room. The display induced hum is independent of the power supply. The fact that you do not hear the hum while on battery power in your office leads me to suspect you have a bad AC adapter upstairs.
Well its not the adapter. The hum doesn't follow the scanner downstairs to my office.
weird.
 

tvengr

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Plug in the scanner using the AC adapter in your office. Then try the scanner on battery power. Let me know if you hear the hum on both power sources. If you are using just the scanner mounted antenna upstairs and the scanner isn't connected to anything else such as an external amplified speaker, there is no reason to suspect ground loop hum.
 

vanhalo

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Plug in the scanner using the AC adapter in your office. Then try the scanner on battery power. Let me know if you hear the hum on both power sources. If you are using just the scanner mounted antenna upstairs and the scanner isn't connected to anything else such as an external amplified speaker, there is no reason to suspect ground loop hum.
In my office i don't hear the hum on either power source.
 

tvengr

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In my office i don't hear the hum on either power source.
Sounds like the AC adapter is not the problem. What frequencies and systems are you monitoring? USB power sources are notorious for radiating noise over a wide range of frequencies. Any kind of appliances and electrical or electronic devices such as radios and TV's can radiate interfering signals. Since you just started having the interference, I would unplug any devices, especially those recently purchased, to see if the interference disappears. If you are in a townhouse, check if your neighbors recently purchased anything new or moved something upstairs. Tracking down interference problems can take a lot of detective work.
 
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vanhalo

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Sounds like the AC adapter is not the problem. What frequencies and systems are you monitoring? USB power sources are notorious for radiating noise over a wide range of frequencies. Any kind of appliances and electrical or electronic devices such as radios and TV's can radiate interfering signals. Since you just started having the interference, I would unplug any devices, especially those recently purchased, to see if the interference disappears. If you are in a townhouse, check if your neighbors recently purchased anything new or moved something upstairs. Tracking down interference problems can take a lot of detective work.
There were no changes to my listening habits. I have a few favorites list that I am scanning. I have been using it solid for 2 weeks. Same frequencies.
It just decided to start humming today.
I have moved it around the house to a mag mount antenna and with the stock antenna. I have only heard the hum in one place.
When I move it back upstairs in a few hours I will see if the hum is back.
 

kruser

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It sounds like the "mitigation" part, as Uniden called it, may have shifted during one of the moves and may have no longer been providing an effective ground. The next move of the radio allowed the connection to ground again. Just a guess of course but it is possible.

There's been zero proof that Uniden fixed the hum in recent production units the correct way by providing proper grounding like some of us have done. I think Uniden still relies upon the "mitigation" part to remove hum.
 

RandyKuff

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Just my 2 cents...
Being that the "mitigation part" does not really have a solid mechanical connection...
I could see it possibly suffering from oxidation over time maybe...
 

Anderegg

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Use the record feature to record the NOAA weather in both locations and playback in both locations...to ensure your audio enviornment isn't altering your earspective.

Paul
 

trentbob

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It sounds like the "mitigation" part, as Uniden called it, may have shifted during one of the moves and may have no longer been providing an effective ground. The next move of the radio allowed the connection to ground again. Just a guess of course but it is possible.

There's been zero proof that Uniden fixed the hum in recent production units the correct way by providing proper grounding like some of us have done. I think Uniden still relies upon the "mitigation" part to remove hum.
So I just got my second 200 from the recent load into Bearcat Warehouse last week. It is number 1089 made in 2020.

I was amazed to see it did not have a a hum like the other unit did before I fixed it.

I have an external speaker plugged into the Jack in the back and if I put my ear pressed hard up against the speaker I do hear that old familiar sound but it's very hard to hear. As soon as I move my ear away it's gone.

The mitigation devices have shifted, before I did the permanent fix I had bent my mitigation device so it fit a little tighter and it also had added copper tape. It was pretty snug.

I'm going to be careful not to hang around the radio and to be very careful. I was pleased to see the absence of the hum.
 

vanhalo

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Listening to it right now upstairs. No hum. I am not sure what was going on on Saturday but I don't hear it anymore.
 

crippledchicken

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So I just got my second 200 from the recent load into Bearcat Warehouse last week. It is number 1089 made in 2020.

I was amazed to see it did not have a a hum like the other unit did before I fixed it.

I have an external speaker plugged into the Jack in the back and if I put my ear pressed hard up against the speaker I do hear that old familiar sound but it's very hard to hear. As soon as I move my ear away it's gone.

The mitigation devices have shifted, before I did the permanent fix I had bent my mitigation device so it fit a little tighter and it also had added copper tape. It was pretty snug.

I'm going to be careful not to hang around the radio and to be very careful. I was pleased to see the absence of the hum.
I removed the mitigation part as I didn't like the idea of just pressure on top of the display module trying to get a proper ground.and, wondered if maybe the pressure of the mitigation part might be causing the display failures some people have had. I did the static discharge mod without mitigation part in fear for my display module. :)
 

trentbob

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I removed the mitigation part as I didn't like the idea of just pressure on top of the display module trying to get a proper ground.and, wondered if maybe the pressure of the mitigation part might be causing the display failures some people have had. I did the static discharge mod without mitigation part in fear for my display module. :)
I have definitely thought that maybe the mitigation device was causing the lines and display failures but I do remember the first display failure was before the mitigation part was distributed for free for self installation, I'm pretty sure. However, I wonder if the grounding problem itself was causing the display failures.

Yes, once you've done the permanent fix you certainly can remove the mitigation device if you wish, it's irrelevant at that point.
 

crippledchicken

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I've wondered about the grounding problem also, maybe causing the display failures kind of like screwing a light bulb in and out numerous times causing it to blow or, just leaving it loosley in the socket. :)
 

djeplett

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Now you guys got me thinking I should just bite the bullet and do the permanent fix to my 200. I have a very little "hum" that I can hear if the room is quiet and I'm near to the external speaker I use. It wasn't so bad that I figured I'd leave well enough alone. But if doing the fix could eliminate the possibility of the screen issues maybe I should just go for it.
 

werinshades

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But if doing the fix could eliminate the possibility of the screen issues maybe I should just go for it.
I don't think that has been confirmed. If you're having "screen flicker" issues, that has to be returned to Uniden, it's a known problem that others have reported.
 

djeplett

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I don't have any of the display issues yet, but it is a compelling theory that the grounding issues could eventually cause them.
 
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