TRX-1: TRX-1 Popping Sound

[ScannerHam]

Sent my TRX-1 to Whistler for repairs a month ago as most transmissions were covered with a loud squealing noise over the audio. Sometimes I received a transmission without the loud squealing noise that sounded like a single side band transmission (not an encrypted signal). They replaced the Antenna Module and noted that the SD card had errors copying files, so they reformatted the SD card and updated the library and data.

After getting the TRX-1 back from Whistler, I now hear a popping sound at the beginning and end of transmissions on trunked and non-trunked systems. The P25 trunk system also has multiple popping sounds when it is scanning the trunk system and there is no radio traffic. This is not a squelch problem with noise coming thru as the squelch is set high to a 9. Before the loud squealing noise problem, the TRX-1 worked great.

I checked all the settings (including ADC gain & DAC gain) and they are set correctly.

I also have a TRX-2 scanning the same trunked and non-trunked systems with the same settings and there are no issues like the TRX-1.

I am going to send Whistler an email describing these issues. If anyone has any ideas to fix this problem, please post them here. Otherwise the TRX-1 goes back to Whistler again.

 

[Ubbe]

After getting the TRX-1 back from Whistler, I now hear a popping sound at the beginning and end of transmissions on trunked and non-trunked systems. The P25 trunk system also has multiple popping sounds when it is scanning the trunk system and there is no radio traffic.

It's a DC issue in the audio circuit. When it mutes and unmute it's controlling the power to a amplifier to the speaker, no reason to keep it powered while not monitoring a conversation and to preserve battery life. I could be related to a battery save mode but I haven't seen any user configuration for that so perhaps its firmware related. Try changing how the backlight are configured, set it to other than Normal, before sending it it back to Whistler.

/Ubbe

 

[Whistler_Support]

If this is only occurring on Digital transmissions, you may want to try updating the DSP just incase the DSP file somehow became corrupted.

 

[tvengr]

It has been my experience that a pop in the audio is caused by a change of the DC level on the input of an audio amp. Since it is occurring at the beginning and end of transmissions, the output of the squelch switching voltage may be getting into the audio amp input. That is often caused by a shorted electrolytic capacitor.

 

[RaleighGuy]

If this is only occurring on Digital transmissions, you may want to try updating the DSP just incase the DSP file somehow became corrupted.

It is great to see @Whistler_Support is back responding to these posts. Thanks for the continued support of your scanners and users.

 

[ScannerHam]

Thanks to everyone for all the information. I have been in contact with Whistler Support via email. They are checking for an answer to my reception problem and will get back to me next week. If they cannot solve the problem, I will send the scanner back to them again for repair (no additional repair charge).

 

[kmartin]

Keep us posted on this