Xiegu G90 squawk at high volume

 On the G90 Groups is an interesting discussion about an audio feedback (squawk) at high volume.

The subject is now locked but I think it will be a good added value to point to the source and the solution.

As I wrote there,  the problem is most probably due to the MLCC capturing audio and producing a feedback via the PCB.

It is a known phenomenon that cheap MLCC act like condenser microphones.

Today, I opened for the last time my G90 to put back the LDOs as the small SMPS put some spurious into 20m band and this radio will be put on sold.

I did some photos on the front end bandpass filters (see this post) for future reference and I get back to a small soft plastic cylinder placed on the shield above the filters.

I did noticed it a while ago and  I didn't payed attention until now with that discussion in my "rear memory".

Yup, this is precisely what I reccomended to reduce that squeal, a simple damper to reduce the vibration between the upper case that hold the speaker...

It will be interesting to check if those radios that exhibit the audio feedback have that little plastic damper. 

If not, I think it would be easy to add something similar or a little piece of foam. 

 

Baofeng DM-32 Desktop Charger YPT-C21A

 Baofeng DM-32 desktop "charger" isn't a proper charger but a desktop stand with a charging indicator.

The charging circuit is built into the battery and powered by a 5V/1A power supply.

Inside the desktop stand is a detection circuit that change the colour of a dual-colour LED based on a LM358 dual op-amp configured as a comparator.

Here is the schematic:

 

 

"My SD card is not detected by the Marauder"

 When using Marauder, an SD card it's a must.

Unfortunately, the smallest SDcards i have are no less than 64GB so, according to the author, it will not work.

 

Not so fast, mate!

See? 

 

Where there is a will, there is a way! After all, I am a "brave ham"!

Here is how was done. Attention, instruction follows, mind the gap....

|   |  

Open CMD in Administrator Mode. (Windows key and type CMD then select in the right side of the  folding whatever-is-that-called "Run in Administrator").  This was in Red and Bold because I consider it very important. Also because those below will not work otherwise.

Then, following commands:

        diskpart

        list disk 

Search for your 64 GB (or 128 GB) SD card "disk".  An SD card of  64GB will be shown as "Disk 2 58 GB".

 Note the number of the disk; be aware, usually the Disk 0 has your precious Windows!

       select disk # ( where # is your number).

Now, you will have "Disk # selected" and write:

        clean

        create partition primary

 You can then try 

        format fs=fat32 quick

        assign

        exit

but most probably, you will get an error after "create partition primary", something like "virtual disk service error: the volume size is too big".

Don't worry! 

If so, go download an old piece of software from Ridgecrop,  called fat32format.exe.

Yeah, it's a ugly scary EXE!

Extract it and save it in a well lit place easy to reach it. I save it on C to look like this:

     C:\ fat32format.exe

Good.

 

At this point, the SD card should be listed, but inacessible in Explorer.

Note down the letter under the SD card is hiding.

Open (again), the CMD, also in Adminstrator mode.

Write this:

     C:\fat32format.exe E:

(where E: is how my SD card was listed in Explorer).

After some babble on the screen, the SD card will be as new as a newborn, in FAT32, ready to be thrown in Marauder.

 

That's all folks!