SDS200 pop sound from speaker when squelch opens and closes only in AM mode

Kaleier1

Member
Joined
Dec 27, 2019
Messages
222
The first SDS200 I bought had to be returned because there was an annoying pop at the beginning an end of every transmission no matter what mode including DMR. The second one I bought did not have that problem. I programmed a favorites lists for VHF aviation frequencies which uses AM in the second SDS200 I bought and listened to it for a while and don't remember having any problems.

I am not a big fan of aviation communications so hadn't listened to it again until today, but now found I get a pop or click sound coming out of the speaker every time the squelch opens and closes on all frequencies. It does it with signals and if I manually turn the squelch knob to open and close the squelch. Even tried it on the CB radio band at 27 MHz and it does the same thing. It varies in intensity with the volume setting. If the volume is at zero I don't hear it. If I turn the volume up to a comfortable listening level it is quite loud (louder than the transmissions by about 4 times and about 10 times louder than the noise floor static) and very annoying. If I leave the squelch open it doesn't do it when there are signals so it is definitely not the transmitting stations.

I did the permanent fix for the hum so have the audio amp option set for infinite and changing filter settings doesn't help.

Does anyone else have this problem with their SDS200 in AM mode?
 

n1chu

Member
Premium Subscriber
Joined
Oct 18, 2002
Messages
779
Location
Farmington, Connecticut
I don’t have the popping sound you refer to but in AM mode the volume of the received signal starts high and then tapers off. I’m thinking a slow AGC, but only while in AM mode. The first thing I tried was resetting the scanner to factory defaults and then programming only AM frequencies. In my case it didn’t solve the problem but it’s a good place to start with your popping issue. Then, if it is not corrected, try other suggestions (yet to be posted here).
I’m hoping Uniden will be coming out with firmware/software updates after they get back at it (if the pandemic has shut them down temporarily). After all, the radio is their first scanner attempt at SDR (Software Defined Radio) which should make upgrades/updates easier than coming out with a newer version of the scanner. In theory, a newer or follow-on version of the SDS models shouldn’t be necessary as we’ve seen in the past with other models. (I believe the BCDx36HP’s, originally touted as their premier flagship offering, was only improved upon with the SDS models due to the issue they were having with simulcasting, a problem that could not be corrected with firmware updates only... a new design was necessary. Otherwise, they probably would have stuck with the BCDx346HP’s longer before offering a newer model. The rush to market with the SDS100, which I believe was obvious, probably had more to do with the simulcast issue... more so than simply trying to stay ahead of other manufacturer offerings.)

Try the factory reset first... save your current programming.

And, thanks for giving a detailed accounting of your radio’s issue up front. I wish all help requests were as well written as yours.
 

Kaleier1

Member
Joined
Dec 27, 2019
Messages
222
Thank you for the reply. I will try that and a new memory card as that seems to cause issues as well.
 

Twister_2

Member
Feed Provider
Joined
Mar 1, 2008
Messages
543
Location
Dauphin County, PA
The first SDS200 I bought had to be returned because there was an annoying pop at the beginning an end of every transmission no matter what mode including DMR. The second one I bought did not have that problem. I programmed a favorites lists for VHF aviation frequencies which uses AM in the second SDS200 I bought and listened to it for a while and don't remember having any problems.

I am not a big fan of aviation communications so hadn't listened to it again until today, but now found I get a pop or click sound coming out of the speaker every time the squelch opens and closes on all frequencies. It does it with signals and if I manually turn the squelch knob to open and close the squelch. Even tried it on the CB radio band at 27 MHz and it does the same thing. It varies in intensity with the volume setting. If the volume is at zero I don't hear it. If I turn the volume up to a comfortable listening level it is quite loud (louder than the transmissions by about 4 times and about 10 times louder than the noise floor static) and very annoying. If I leave the squelch open it doesn't do it when there are signals so it is definitely not the transmitting stations.

I did the permanent fix for the hum so have the audio amp option set for infinite and changing filter settings doesn't help.

Does anyone else have this problem with their SDS200 in AM mode?
What's different about your new unit that it doesn't pop? This is a rhetorical question for you and meant to stir a discussion about why some SDS200s pop and others don't. I had a post about this topic back in January and many people got defensive about their radios NOT popping but could never post a video showing that it truly doesn't pop. So, I'm wondering if Uniden changed something and also if anybody has successfully sent their unit back to Uniden for repair.
 

N4DJC

Member
Premium Subscriber
Joined
Apr 24, 2019
Messages
430
Location
Upstate
Mine has it too, but it's a very minimal pop at the beginning and end of transmission. The pop gets a bit louder with volume changes. I can hear it through the speaker, headphones, and external speaker.

I've done the static discharge mod and it eliminated the hum, total silence. And removed the mitigation part.

I'd be interested in hearing any positive fixes from other users, or from a Uniden repair.
 

Kaleier1

Member
Joined
Dec 27, 2019
Messages
222
What's different about your new unit that it doesn't pop? This is a rhetorical question for you and meant to stir a discussion about why some SDS200s pop and others don't. I had a post about this topic back in January and many people got defensive about their radios NOT popping but could never post a video showing that it truly doesn't pop. So, I'm wondering if Uniden changed something and also if anybody has successfully sent their unit back to Uniden for repair.
The new unit has a lower frequency and louder pop on AM mode only. Just opening and closing the squelch in AM duplicates the pop. The old scanner did it on any mode.

I didn't recall the pop in AM mode when I first go the new unit. I did do the Static Discharge grounding mod which cured the hum but wonder if that did something to cause the pop, however I haven't heard anyone else mention it.

I remember your posts when I posted about my first unit popping. You were going to send yours to Uniden before the warranty ran out. I am going to do the same, probably around December.
 

N4DJC

Member
Premium Subscriber
Joined
Apr 24, 2019
Messages
430
Location
Upstate
@Kaleier1

I don’t think the SD fix has anything to do with it. But the speaker is a pretty tight fit in the case. The capacitor discharge may be the most likely explanation. It‘s coming through the audio amp

I wish I could get a schematic. I would enlist my EE PhD brother in law to take a look at it. He’s a really smart guy, with a lot of practical experience designing circuits.

There doesn’t seem to be enough interest to dig into it. I may send mine back, but the thought of paying shipping both ways without a resolution doesn’t appeal to me.
 

Twister_2

Member
Feed Provider
Joined
Mar 1, 2008
Messages
543
Location
Dauphin County, PA
Yeah, I'm not sure if I want to pay for shipping if they might not even fix it. I would like to know from Uniden first that they have fixed and will fix the speaker pop. Maybe I'll call on Monday.
 

VA3SOM

Member
Premium Subscriber
Joined
Aug 17, 2009
Messages
174
Location
Ontario, Canada
I had this when i plugged anything but headphones into the front audio jack. But it was on anything and even moving around the menu.
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
12,104
Location
VA
I had this when i plugged anything but headphones into the front audio jack. But it was on anything and even moving around the menu.
You created a ground loop. The scanner doesn't like that.
 

RandyKuff

Member
Premium Subscriber
Joined
Oct 15, 2015
Messages
777
Location
Lorain, Ohio
An interesting thing I noticed from the BC23-A speaker manual... I'm assuming your BC20 is that way too...

Speaker.jpg
 

Kaleier1

Member
Joined
Dec 27, 2019
Messages
222
I have an update.

My SDS200 is normally connected to an outdoor 800-900 Mhz 9 element yagi antenna on my roof since that is mainly what I listen to.

A couple days ago the President was leaving in Air Force 1 so I tuned to the aviation band to see if I could hear anything from the airport. Knowing the outdoor yagi was not good for VHF frequencies I switch to the telescoping whip that comes with the SDS200 and the popping was gone. Also tried an indoor whip antenna that came with an SDR USB dongle and again the popping was not present.

With the indoor antennas I hear the pop every once in a great while and there is sometimes a slight pop if I listen with my ear close up to the speaker, but while listening normally I don't hear it and it is not a problem.

With the outdoor yagi attached the popping sound is constant and loud, even just opening and closing the squelch.

I haven't done any further investigation yet to determine why this is but will look into it to see if I can isolate what the issue is.
 
Top