SDS200: SDS200 pop driving me crazy!

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N8SHA

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I originally bought the SDS200 because of its reputation for working well with simulcast systems - most of them I listen to are simulcast.

I was rather dismayed to find out that I had the dreaded hum problem, along with a popping noise when the squelch opens. Order the free shim from Uniden, popped open the scanner to discover it was already installed. So, I disassembled the unit per instructions elsewhere on the forums, scraped the lacquer off, etc. I even soldered the little jumper as recommended by another user. Result was that the hum is gone, the pop is still there, and it is driving me batty.

At this point, I really don't know what to do. (Scanner is out of warranty)

I'm seriously considering purchasing an 800 MHz range yagi antenna, a Stridsberg Engineering Passive Multicoupler and feeding it with my discone and the yagi, and switch back to my BCD536HP. I have no idea if it would work, but it would potentially be less expensive than ordering another scanner (which might not work)

Banging my head against the wall and looking for suggestions.

-Matt
 

buddrousa

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Search the forums UPMan posted about settings for the Audio Amp that may help your problem.
In Sentinel Mis AUDIO TIMER what is the setting?
 
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djeplett

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Buddrousa is on to it I think. Go into your settings on the radio and try setting the Audio Off Time to "Infinite". I think when I experimented with setting it to anything other than infinite there was a pop. Now that you did the hum mod you can set it to infinite. I believe the Audio Off setting was an attempt to mitigate the hum.
 

phask

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If the audio off timer does not eliminate it then try another SD card.

I had one in a 536 that would do this, re-formatted and did it in the 200 as well. I just quit using it :) It also was noisy when I formatted it.
 

scnrfrq

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I originally bought the SDS200 because of its reputation for working well with simulcast systems - most of them I listen to are simulcast.

I was rather dismayed to find out that I had the dreaded hum problem, along with a popping noise when the squelch opens. Order the free shim from Uniden, popped open the scanner to discover it was already installed. So, I disassembled the unit per instructions elsewhere on the forums, scraped the lacquer off, etc. I even soldered the little jumper as recommended by another user. Result was that the hum is gone, the pop is still there, and it is driving me batty.

At this point, I really don't know what to do. (Scanner is out of warranty)

I'm seriously considering purchasing an 800 MHz range yagi antenna, a Stridsberg Engineering Passive Multicoupler and feeding it with my discone and the yagi, and switch back to my BCD536HP. I have no idea if it would work, but it would potentially be less expensive than ordering another scanner (which might not work)

Banging my head against the wall and looking for suggestions.

-Matt
When does the popping occur? When a transmission starts, or when it ends?
 

N8SHA

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Tried the Audio Off Time several times in the past. It's currently set at Infinite. I've toggled it back and forth between different settings hoping maybe it was "stuck" (I've seen weirder.)

The SD card was a new one - just tried that and it no difference.

Popping happens when the TX starts.

-Matt
 

KevinC

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I seem to remember another member recently reporting the "pop", I suggested the audio timer and he too said it made no difference.

Aha! It was @N8SHA as well...

 

N0UDG

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I also have a “Pop” (in both SDS100 & SDS 200) although it is sometimes more like a delayed squelch opening, sort of like what an electrical short some place in one’s house would sound like if of very short duration.

I pulled the main circuit breaker for the house, used the radios on DC or AC, changed to an outside antenna, used all possible combinations of filters, ATT, SQ settings both in amount and codes (CTCSS/DSC), and I have even gone mobile in case it was a cracked AC power insulator on the power lines outside my house. NONE of this made any difference. The SDS200 audio amp adjustments does really help with a hum or buzz like sound but it is always present in the background unless I use the audio amp adjustment. So maybe we have more than one kind of ‘POP” sound.

I have never heard this ‘POP” except on analog nontrunked signals and it is almost always at the very beginning. In a three day recording of the local PD 155.550 MHz analog nontrunked (8 hour recording with one-half second between calls) it occurred 89 times and all but 7 were at the very beginning of the transmission. These 7 “Pops” were by themselves as though someone had pressed the mic button but did not say anything.

However, it does not happen every time as can be seen in the recording above nor does if occur on but ONE other analog VHF Highband frequency, therefore, on most analog nonturnced signals I do not hear it.

Summary for the “POPS” I am hearing: (for my radios in my listening situation) – YMMV
  • Only hear it on certain analog nontrunkced signals
  • I do not hear it every time even on these 2 VHF analog signals
  • I have never heard it on digital signals trunked or not
  • I cannot change this behavior by adjusting user addressable settings or combinations of these setting, antenna changes, etc. thus far
  • I do not listen to my SDS scanners that much unless we have tornadoes around therefore, this “POP” may be more common on other frequencies than I think

    Related side note:
    Neither the SDS100 or 200 can monitor the local Civil Defense analog nontruncked (152.300 MHz, Butler County MO) for more than a few seconds (None of my other Uniden, GRE, Radio Shack scanners have this problem). This -45dB signal will drop out totally as though a very strong signal desensed the front end of the radio or they just stopped transmitting. I have used as many as five scanners to monitor this situation and no other strong signal was heard at that time nor did they stop transmitting. However, when 152.300 MHz (CD WX1) transmits you will also hear it on 157.560 MHz which is Civil Defense WX2). Perhaps in the SDS radios that are mixing?

    Interestingly the mobiles using the same repeater, on the same output frequency and with the same signal strength never drop out on the SDS100 or 200.

    I have tried all that is listed above to address this problem and it has made NO difference in this behavior.

    I have made a couple of very short LOG files of this situation.
 

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Ubbe

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This -45dB signal will drop out totally as though a very strong signal desensed the front end of the radio or they just stopped transmitting.
Have you tried the attenuator on that frequency, perhaps together with different filter settings like Normal and Invert? You could also try the IFX setting on that frequency.

Do you have any $10 SDR dongle or other receiver that can be used to watch the whole frequency spectrum so that you really can see what's going on?

/Ubbe
 

N8SHA

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First, to follow up on some of the previous questions... It happens on all frequencies, conventional analog, trunk digital, etc. Whenever the squelch opens. I do have a couple of digital priority channels, but there never seems to be a pop once the squelch opens. No WX priority channels.

So, toying with WX channels, I just discovered something....
I put it into WX scan mode to pickup one of the local NOAA frequencies. While the scanner is locked onto the frequency, if I turn the volume up and down, when it hits level 0, I get the pop. It happens both on turning volume up from 0->1 and down from 1->0.

-Matt
 

Stecomp

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I also have the pop on both of my 200's at the end of a transmission. My original unit was purchased the first day they were available and as I reported here over a year ago had the constant hum along with the accompanying pop. Sent radio in right away and according to Upman it was used as a test bed for the new mitigation part.

The part took care of the constant hum but it was still somewhat noticable during a transmission along with the pop still there but reduced. This was entirely acceptable in the room it was being used in. I totally eliminated the hum and pop when I got the ground loop isolater from Amazon and plugged it in the back of the radio and connected an old Uniden speaker.

I added another 200 just recently and it had a very mild hum and pop during a broadcast. This is a newer unit I got as a demo and had the mitigation part installed. I did the StaticDischarge lacquer scrape and that totally eliminated the hum but the pop is still there at the end of transmission.

I have tried all the Audio Off settings with no difference. I use the radio exclusively for P25 systems but it also pops on conventional ones. Interestingly when I set Audio Off to infinite I get the pop at the beginning and end of each signal but set at 100 Ms only get it at the end. Since this radio is being used in a quieter room from it's brother, the low key pop is more noticeable but still not enough to make it difficult to listen. Still might have to get another isolater and speaker if I keep focussing on it.
 

kruser

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First, to follow up on some of the previous questions... It happens on all frequencies, conventional analog, trunk digital, etc. Whenever the squelch opens. I do have a couple of digital priority channels, but there never seems to be a pop once the squelch opens. No WX priority channels.

So, toying with WX channels, I just discovered something....
I put it into WX scan mode to pickup one of the local NOAA frequencies. While the scanner is locked onto the frequency, if I turn the volume up and down, when it hits level 0, I get the pop. It happens both on turning volume up from 0->1 and down from 1->0.

-Matt
What are you using for a speaker? The SDS200's internal speaker or some kind of external speaker.
 

scnrfrq

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I also have the pop on both of my 200's at the end of a transmission. My original unit was purchased the first day they were available and as I reported here over a year ago had the constant hum along with the accompanying pop. Sent radio in right away and according to Upman it was used as a test bed for the new mitigation part.

The part took care of the constant hum but it was still somewhat noticable during a transmission along with the pop still there but reduced. This was entirely acceptable in the room it was being used in. I totally eliminated the hum and pop when I got the ground loop isolater from Amazon and plugged it in the back of the radio and connected an old Uniden speaker.

I added another 200 just recently and it had a very mild hum and pop during a broadcast. This is a newer unit I got as a demo and had the mitigation part installed. I did the StaticDischarge lacquer scrape and that totally eliminated the hum but the pop is still there at the end of transmission.

I have tried all the Audio Off settings with no difference. I use the radio exclusively for P25 systems but it also pops on conventional ones. Interestingly when I set Audio Off to infinite I get the pop at the beginning and end of each signal but set at 100 Ms only get it at the end. Since this radio is being used in a quieter room from it's brother, the low key pop is more noticeable but still not enough to make it difficult to listen. Still might have to get another isolater and speaker if I keep focussing on it.
I have a slight whine and a very light pop sometimes. Tried a ground loop isolator with a Realistic speaker. Totally silent from that speaker, but I have to increase volume from 8 to 23. Is that normal? Also the isolator only works in one direction - normal too?
 

crippledchicken

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I also have a “Pop” (in both SDS100 & SDS 200) although it is sometimes more like a delayed squelch opening, sort of like what an electrical short some place in one’s house would sound like if of very short duration.

I pulled the main circuit breaker for the house, used the radios on DC or AC, changed to an outside antenna, used all possible combinations of filters, ATT, SQ settings both in amount and codes (CTCSS/DSC), and I have even gone mobile in case it was a cracked AC power insulator on the power lines outside my house. NONE of this made any difference. The SDS200 audio amp adjustments does really help with a hum or buzz like sound but it is always present in the background unless I use the audio amp adjustment. So maybe we have more than one kind of ‘POP” sound.

I have never heard this ‘POP” except on analog nontrunked signals and it is almost always at the very beginning. In a three day recording of the local PD 155.550 MHz analog nontrunked (8 hour recording with one-half second between calls) it occurred 89 times and all but 7 were at the very beginning of the transmission. These 7 “Pops” were by themselves as though someone had pressed the mic button but did not say anything.

However, it does not happen every time as can be seen in the recording above nor does if occur on but ONE other analog VHF Highband frequency, therefore, on most analog nonturnced signals I do not hear it.

Summary for the “POPS” I am hearing: (for my radios in my listening situation) – YMMV
  • Only hear it on certain analog nontrunkced signals
  • I do not hear it every time even on these 2 VHF analog signals
  • I have never heard it on digital signals trunked or not
  • I cannot change this behavior by adjusting user addressable settings or combinations of these setting, antenna changes, etc. thus far
  • I do not listen to my SDS scanners that much unless we have tornadoes around therefore, this “POP” may be more common on other frequencies than I think

    Related side note:
    Neither the SDS100 or 200 can monitor the local Civil Defense analog nontruncked (152.300 MHz, Butler County MO) for more than a few seconds (None of my other Uniden, GRE, Radio Shack scanners have this problem). This -45dB signal will drop out totally as though a very strong signal desensed the front end of the radio or they just stopped transmitting. I have used as many as five scanners to monitor this situation and no other strong signal was heard at that time nor did they stop transmitting. However, when 152.300 MHz (CD WX1) transmits you will also hear it on 157.560 MHz which is Civil Defense WX2). Perhaps in the SDS radios that are mixing?

    Interestingly the mobiles using the same repeater, on the same output frequency and with the same signal strength never drop out on the SDS100 or 200.

    I have tried all that is listed above to address this problem and it has made NO difference in this behavior.

    I have made a couple of very short LOG files of this situation.
I don't have the pop but, I do get the drop outs on 152.300 on my sds200 there is also, some type of security service I hear on that same frequency as well as severe weather watch when there are storms close by.
 

maus92

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I have a slight whine and a very light pop sometimes. Tried a ground loop isolator with a Realistic speaker. Totally silent from that speaker, but I have to increase volume from 8 to 23. Is that normal? Also the isolator only works in one direction - normal too?
The barely audible "whine" is from data being written to the display. Use the audio time off setting - mine is set to 500ms. TBH, I don't find this to be a big deal since my radios are used in a work environment where there are other much louder noise sources.
 

Stecomp

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What are you using for a speaker? The SDS200's internal speaker or some kind of external speaker.
I am using a Uniden ESP12 (unamplified) speaker with the isolater on the older one and just the internal one for now on the new one. If I plug the speaker in to the back of the 200 without the ground loop isolater the noise is magnified.
 
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