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

 

[ScannerHam]

Sorry about the delay in posting the status of my TRX-1.

Sent the TRX-1 to back to Whistler a second time for repairs. This time they sent me a replacement TRX-1. The squealing noise over the audio is gone. The popping sound is still heard at the beginning and end of transmissions on trunked systems. The P25 trunk system also has multiple popping sounds when it is scanning the trunk system and there is no radio traffic.

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.

 

[ScannerHam]

Please disregard my last post above as I cannot delete it. If the moderator can delete this post, it would be appreciated.

Sent the TRX-1 to back to Whistler a second time for repairs. This time they sent me a replacement TRX-1. The squealing noise over the audio is gone. The popping sound is still heard occasionally at the beginning, during, and at the end of transmissions on the Worcester MA P25 trunked system. Some transmissions are loud and clear without any audio issues.

No sure what to do now. Should I send Whistler another email describing the problem? I appreciate them sending me a replacement scanner, but the problem is still not fixed.

I think the problem is as tveng stated above "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."

Thanks to everyone for your input on this problem.

 

[TAbirdman]

If they replaced the radio totally, chances of a second ( totally different radio) doing the same thing is odd. What are you using to power the TRX-1? Since this is a totally different radio and you say the TRX-2 doesn't have this issue, then the only thing that i can think of is how you are powering the TRX-1.

 

[Whistler_Support]

Having 2 TRX-1 units with a similar result while possible, is rather remote.

My guess is both radios are using your original Micro SD card as to replace a unit does not necessarily mean the unit and SD card was replaced.

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

I do not see that you responded to this.

As an experiment you can remove the Micro SD card from your TRX-1, then place it in an adapter to insert it in your TRX-2 to determine if the problem follows the Micro SD card.

If the Problem follows the Micro SD card, I would ask that you update the DSP and see if it corrects the issue.
If it does not correct the issue but you have confirmed the issue follows the Micro SD card, you may have a bad card.

When replacing the Micro SD card, please only use Sandisk brand and do not exceed 32GB.
Format as FAT32 with 32kb clusters
Load your Library and configuration to the Micro SD card
Check DSP for updates

Once completed, please retest and let us know your result.

 

[ScannerHam]

Thanks to everyone for the replies. I did try the TRX-1 4 GB Micro SD card in the TRX-2 with the adapter and it was working OK. I thought I had updated the group on this test.

I am using the original 4 GB Micro SD card that came with the radio.

Maybe the 4 GB Micro SD card that is giving me the problem, not the radio?

Anyway, I will recheck the TRX-1 4 GB Micro SD card again in the TRX-2, plus I have a 32 GB Micro SD card I can try. Last time I used the 32 GB SD card, it took a long time to copy the files from my PC.

All the files on the TRX-1 and TRX-2 are up to date.

I am powering the TRX-1 with the supplied USB cable plugged into a port on a USB wall charger plugged into an AC outlet.

I will let everyone know the results.

 

[TAbirdman]

When you are rechecking everything double check that AC wall USB adapter has at least 1 amp capacity. I ran with one of those cheap 12 volt to USB deals and the backlight was flickering badly. Got one with higher current capacity and the flickering went away.

 

[Ubbe]

TRX-1 takes something like 125mA with the back light on. If I go into the menu system it turns off the receiver and takes 25mA while not scanning. So while you are programming the scanner and you can't anyhow listen to systems it takes minimal power. Smart move by Whistler. I currently have no batteries in mine but charging probably adds something like 200mA, 10-15 hours to charge the batteries.

/Ubbe

 

[wwhitby]

FWIW, I get a low volume "pop" at the beginning and end of transmissions on P25 systems. I had chalked it up to just being the way the TRX-1 operates.

 

[Cheeseburgers]

Every single GRE / RS / Whistler model like this does that, I've owned TRX, 668, 800, 1040 all did it, not a HUGE deal, but once you notice it's not going away 🤣, also the generally poor interference tolerance was enough to write that line off entirely, PSR-800 was sturdily built, but open up that and compare to the RS or 1040, you'll see changes made, maybe due to parts availability... out of the bunch the 800 was the best IMO

 

[ScannerHam]

Did more testing -

Formatted spare SanDisk 32 GB Micro SD Card
Loaded library and configuration to Micro SD Card
Updated Micro SD Card with DSP updates

Still have -

Beginning of some transmissions not heard, only popping sound, then some voice
Popping sound before and after all transmissions heard

I now understand that the GRE / RS/ Whistler models have these issues that I can live with. As I said before, just odd that the TRX-2 does not have any of these issues and receives all transmissions.

 

[ScannerHam]

Update - went back to using the SanDisk 4 GB Micro SD Card with the latest software updates installed. When plugging the USB cable into a USB Adapter plugged into an AC outlet or in the USB port on my laptop, the scanner receives clear transmissions, or I hear a loud squeal over all transmissions.

Turning off the scanner, unplugging the USB cable from the scanner and plugging it back into the scanner sometimes removes the loud squeal. If unplugging the USB cable does not fix the problem, I unplug the USB cable, slide off the back cover and remove the SD card. Inserting the SD card back into the scanner and plugging the USB cable back into the scanner also sometimes solves the problem.

When powering the scanner with AA batteries or running it off a USB adapter thru my car cigarette lighter, I do not get any loud squeals at all. Ordered a new SanDisk 4 GB Micro SD Card thru Amazon, so I will see if that solves the problem.

 

[tvengr]

When powering the scanner with AA batteries or running it off a USB adapter thru my car cigarette lighter, I do not get any loud squeals at all. Ordered a new SanDisk 4 GB Micro SD Card thru Amazon, so I will see if that solves the problem.

If the scanner works OK on USB and batteries, that indicates that your AC adapter has poor voltage regulation. That can certainly cause the scanner to break into oscillation. Run the volume up and down and see if that affects the squeals.

 

[ScannerHam]

Problem solved!! The USB Adapter plugged into the AC outlet was causing the scanner to break into oscillation. I replaced it with another USB Adapter and the problem went away. Thanks to everyone for the help.