BCD996P2 audio blips

[SlipNutz15]

Can anyone tell me why my scanner is "blipping" or "spiking" at the start and end of each transmission. These transmissions are digital and the settings for each are set as digital.

Link to audio: https://www.dropbox.com/s/cvvr744almye9hx/Audio Clips.m4a?dl=0

 

[SlipNutz15]

I'm going to try this again...

Update to previous information, the "pops" are on ALL transmissions, analog and digital.

Can anyone tell me why the beginning and end of transmissions on ALL my 996P2's "pops" when connected to my Barix Instreamer. None of my other scanners do this, just the 996P2s.

Listen to right speaker starting at 18:10 on this clip: http://garchives1.broadcastify.com/1656/20180815/201808151608-630088-1656.mp3

 

[jonwienke]

Do you have ground loop isolators between the scanner and the other device?

 

[SlipNutz15]

All my scanners are plugged into a 12V converter which is plugged in a commercial grade UPS with current filtering

 

[jonwienke]

Doesn't matter. Uniden uses push/pull audio amplifiers, and if either output is grounded, you get artifacts or distortion, and can possibly damage the amplifier.

 

[SlipNutz15]

What kind of ground loop isolator do you recommend?

Any of these?

https://www.bestreviews.guide/rca-ground-loop-isolators

 

[SlipNutz15]

Purchased the top rated GLI. My next question, I’m running two different rigs, the left speaker is a mobile radio and the right speaker is the 996P2. Both headphone to RCA cable to the Barix. Can I use the same GLI for both pieces to GLI both left and right channels?

 

[Ubbe]

When there is a stereo GLI they use two seperate isolation transformers in the box so it is okay to use the two channels for two seperate scanners.

/Ubbe

 

[KF4JYE]

Be careful connecting a stereo ground loop isolator to 2 scanners. Even though these isolators may contain separate transformers for each channel, many share a common ground. This can cause problems for one or both scanners. All isolators which have 3-conductor connectors (such as Mpow) have common grounds. On isolators using RCA or other 2-conductor connectors, you should still check for continuity between the 2 grounds.

 

[SlipNutz15]

The GLI fixed the popping perfectly. Thank you for all who helped.

KF4JYE, the GLI I got has two grounding wire. Both were attached to the grounding post of my 12V converter and I haven’t noticed any issues. Please PM me when you get a chance.

 

[Ubbe]

Even though these isolators may contain separate transformers for each channel, many share a common ground.

There are one + and one - lead going to the isolation transformer that have no connection to ground.
It is the + and - you connect to the scanners audio out.

If there are some common ground it would probably defeat the purpose of a ground loop isolator and should not be advertised as one.

/Ubbe

 

[KF4JYE]

Ubbe,

I agree that a ground loop isolator does not have a common ground between the input and output connectors. However, any GLI with a 3-conductor input connector has a common ground (or - lead) between the 2 channels.

For example, 2 scanners can be connected to a stereo GLI with a 3 conductor connector. Scanner #1 would connect to the the tip and sleeve of the connector, and scanner #2 would connect to the ring and sleeve. Thus, the grounds (or - leads) of the 2 scanners are tied directly together through the common sleeve connection. This can damage the scanners.

 

[SlipNutz15]

Question for either of you. Is the GLI directional? I keep seeing pictures of GLI and the male pig tail is the input and the female part on the box is the output. I have the scanner out in the female and the male end to the Barix. I grounded the two brown ground wires to the 12V converter. The popping stopped.

 

[Ubbe]

They are passive transformers and works in both directions but can have different impedancies on in and out connectors.

/Ubbe