SDS-200 HUM AS of 8-15-2019

[allend]

So I started to have more of a HUM noise again after I installed more Tin Foil. So I took the outside black sleeve off of the radio and still noticed the HUM noise.

So I started to press more pressure on the inner top sleeve that you can take the top off and the HUM noise really sub-sided. Right in the front where the inner metal sleeve is and the black front housing where the LCD display is in the middle of the screen and putting more pressure causing the HUM to actually almost go away. Seems like there is some play or cushion area in between the top metal inner sleeve and where the Uniden mitigation part goes.

So all I did is take the tinfoil and kept folding it in halves and more halves to make sure there is no more cushion in between the part and the outer metal sleeve and put the tinfoil right on-top of the mitigation part and tighten everything down and the noise is almost about gone.

I thought I would start this new thread for serious people that are still having this trouble. NO BS from other people trolling and putting in THEIR TWO CENTS. Just serious people with the SDS-200 radios with the HUM noise.

To the moderator please slap any other people that chime in with no good tech support and give them warnings and delete their post PLEASE> Thank You

 

[allend]

This is where I put the tinfoil that I kept folding more and more in half to take up the space between this inner top sleeve and the mitigation part.

 

[trentbob]

Did you try the 3M double-sided tape with just the bottom sticky in the same spot or is there a reason you're using tin foil instead of the tape?

 

[buddrousa]

Thanks for trying this and posting this as it may be more of a fix for others than some of the other things that have been posted.

 

[frazpo]

Take the part out and give a slight bend downward. I was able to drop the ohm level significantly between the display plate and the body case. This just ensures good contact to the metal surfaces without the use of other items. After doing this the noise level could not be reduced by putting more pressure on it. Indicating it was as good as it gets.

 

[Joe_Blough]

Add more foil. Add copper tape. Install 3M double-sided tape. Bend the mitigation part. Install a sofa cushion. Park a car on top of the top lid.

It's all the same thing, a poor ground connection between the display chassis and top inner metal cover.

The guaranteed fix is here and despite what the message says, it will not void your warranty.

Although the guaranteed fix above solves the problem of the mitigation part not making good contact with the display chassis and may be enough, there is a chance the mitigation part may still not make good contact with the inner top cover.

Myself, I would solder an insulated braided grounding strap between the display chassis and the inner top cover. That way you know you have a solid connection between both points and heat or vibration is not going to make the connection come loose again.

 

[allend]

It would be awesome if somebody could do a video on this with like a GoPro or something with high resolution so we can see the step by step process.

 

[mikewazowski]

Gents, let's try and keep this thread focused on the technical aspects of the "fix" rather than Uniden's response to the issue.

There's already a thread in the Tavern discussing that and we certainly don't need another one.

Thanks.

 

[buddrousa]

Have we as a group come to the conclusion what exactly is the source of the hum some have and others do not?
From the description from some is sounds like stray RF.
From the description from others it sounds like a vibration.
If we as a group could get along and work toward finding the exact cause then a solution could be found.

 

[frazpo]

Have we as a group come to the conclusion what exactly is the source of the hum some have and others do not?
From the description from some is sounds like stray RF.
From the description from others it sounds like a vibration.
If we as a group could get along and work toward finding the exact cause then a solution could be found.

It is not vibration for sure. Proper grounding all but eliminates it down to a barely audible electronic hum. If everyone's was as minor as mine there would be no complaints. You have to have an ear within 6 inches of the speaker in a room with absolutely NO ambient noise to hear it. And this just in between words on a crystal clear digital system. I've also noticed that it's less noticeable on certain systems. I think it depends on the clarity of the system itself. Let me emphasize though. I increased grounding outside of just relying on the uniden fix. Without adding more grounding the hum was far more noticeable and annoying.

 

[frazpo]

Myself, I would solder an insulated braided grounding strap between the display chassis and the inner top cover. That way you know you have a solid connection between both points and heat or vibration is not going to make the connection come loose again.

Joe, While soldering does provide a far more secure contact between the given frames I do not believe it would totally eliminate the issue. I say this having grounded mine to the extent that I have and can still hear it if I make it a point to try to. Actually a screw in ground strap would be best. Solder is hard to get to stick on the frame surface. Like I said in another post. If everyone's was as unnoticeable as mine there wouldn't be any complaints. This is after supplementing the grounding in addition to the uniden part.

 

[iMONITOR]

I don't think adding aluminum or copper foil is a long term solution. I mentioned in another post quite sometime ago (that I can not locate) that putting two dissimilar metals together does make a good electrical connection. This can cause a galvanic reaction causing corrosion. It's accelerate if there is an electrolyte present but that is not always necessary. I learned about this when I worked for General Electric when they were introducing large electric motors with aluminum windings being connected to copper cables. The same problem occurred with they tried to wire houses and buildings with aluminum wire. A corrosion sets up within the connection causing electrical resistance.

Galvanic Corrosion

Galvanic corrosion - Wikipedia

en.wikipedia.org

 

[Joe_Blough]

I don't think adding aluminum or copper foil is a long term solution. I mentioned in another post quite sometime ago (that I can not locate) that putting two dissimilar metals together does make a good electrical connection. This can cause a galvanic reaction causing corrosion. It's accelerate if there is an electrolyte present but that is not always necessary. I learned about this when I worked for General Electric when they were introducing large electric motors with aluminum windings being connected to copper cables. The same problem occurred with they tried to wire houses and buildings with aluminum wire. A corrosion sets up within the connection causing electrical resistance.

Galvanic Corrosion

Galvanic corrosion - Wikipedia

en.wikipedia.org

I think you meant to say "putting two dissimilar metals together does NOT make a good electrical connection:

This is true. It can also cause contact fretting defined by Wikipedia as "wear and sometimes corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration".

 

[iMONITOR]

I think you meant to say "putting two dissimilar metals together does NOT make a good electrical connection:

This is true. It can also cause contact fretting defined by Wikipedia as "ear and sometimes corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration".

Correct, thanks. I was falling asleep at the keyboard and I was too late to edit it.

 

[Joe_Blough]

Joe, While soldering does provide a far more secure contact between the given frames I do not believe it would totally eliminate the issue. I say this having grounded mine to the extent that I have and can still hear it if I make it a point to try to. Actually a screw in ground strap would be best. Solder is hard to get to stick on the frame surface. Like I said in another post. If everyone's was as unnoticeable as mine there wouldn't be any complaints. This is after supplementing the grounding in addition to the uniden part.

Soldering may not totally eliminate the issue but it would eliminate it as much as possible without the likely hood of it coming back.

As for a screw in ground strap, that was my suggestion to Uniden which I posted in the other thread several days ago -

"Have the top metal cover manufactured with a threaded stud and use an insulated braided grounding strap secured to this top metal cover's thread stud with a nut and star washer. The other end of the braided grounding strap is soldered to the display chassis.

The braid allows it to move and flex without breaking (like a wire would) when taking off the top metal cover. The threaded stud allows you to remove the nut to disconnect the braid completely from the top metal cover so you can get the cover out of the way for any repairs. Having the braid insulated will keep it from shorting anything out when you put the cover back on. Soldering to the display chassis prevents having to redesign the display chassis to include a threaded stud and nut (if it would even fit) which would be a lot more costly than just changing a metal plate to include a threaded stud.

Now you have a securely connected ground that doesn't depend on how tightly the top metal cover is put on (like the Uniden metal piece) and won't come undone from heat or vibration, and which still allows the top cover to be removed."

 

[kmh603]

Go to "Edit Profile" then go to "Miscellaneous" then change Audio time out from infinite to 1 second and the hum goes away!

 

[iMONITOR]

Go to "Edit Profile" then go to "Miscellaneous" then change Audio time out from infinite to 1 second and the hum goes away!

That didn't work for me. Hum was very apparent during the reception of signals.

 

[HighDesertRadio]

When installing electrical distribution systems it is common to terminate copper wire to aluminum lugs. We use NOALOX Anti-Oxidation joint compound promotes good ground continuity through the joint. It also helps with continuity when vibration is present.

 

[iMONITOR]

When installing electrical distribution systems it is common to terminate copper wire to aluminum lugs. We use NOALOX Anti-Oxidation joint compound promotes good ground continuity through the joint. It also helps with continuity when vibration is present.

Correct, but Uniden is not supplying that or even suggesting that.

 

[radio3353]

When installing electrical distribution systems it is common to terminate copper wire to aluminum lugs. We use NOALOX Anti-Oxidation joint compound promotes good ground continuity through the joint. It also helps with continuity when vibration is present.

So I understand correctly, you are suggesting we buy NOALOX and slather the Uniden mitigation part in it before installing the part? Is there a problem if the NOALOX spreads into a conductive area on the PC board? Thanks.