Batboard

I have a XPR4550 that makes a popping noise through the front speaker when it is turned on. This popping noise will
also happen if the radio is left with the DC power turned off and then applied. This noise only comes through the speaker.
No external speaker is connected. Any ideas as to what is causing this would be appreciated.

Thank You,

Vin1450

Every single XPR4500/4550 that I've ever touched (lost count at this point) does that but I've never seen an explanation as to why exactly. If everything else is working fine, I wouldn't worry about it.

KG4INW, Thanks for the reply. Strange that no one has ever explained why it does this!

Vin1450 - NY5AR

You're welcome. Every first generation TRBO mobile, even brand new from the factory does it so it's clearly just part of the design. Maybe I'll poke around the service manuals and see if they offer any explanation. We had a cabinet full of 10 4550 control stations that were all fed by one circuit. As soon as we applied AC power, you'd hear that popping noise simultaneously and amplified! The second generation radios don't do it.