uv88 Some notes on the TYT UV88.
Frequency unlocking & more.. 

Unlock via the keyboard

To access out-of-band frequency programming.
With the set OFF, simultaneously press keys 1 and 7 on the keyboard and keep them pressed.
Switch on the set until the appearance of the number 7, and if you have the voice guide in service, the announcement of "SEVEN".
Release the keys.

Unlock via the programming software TYT v1.17

To unlock the frequencies, tools and test modes of your TYT UV-88:

Find and install UV-88 software (default in C:/UV88 V1.00)
In the Uv88_SoftWare_Eng subdirectory, edit the configuration file setting.ini.
Change the OwnUsed value to ARRVIN and save the file. It will now be necessary to run the software in administrator mode.
Launch the TH-UV88.exe software, a popup window will open to ask you for an activation code. Enter 13636922224

You now have access to test mode and factory settings.
To unblock frequency bands:
Open the Frequency range menu in the left column.
Press the p key to open another popup window.
Enter the code 13636922224 and choose the desired frequency bands.
Transfer the data to the UV88 station.

Test and factory sttings

uv88 angle set The factory settings window is available through the Setting menu and Basis Adj.
The menus are not fully translated, the consequences of incorrect handling are therefore dangerous and at your own risk !

With Google Lens, I could translate the menus. The software is mainly used to control the audio levels...

Firmware update
The latest version of the firmware is available here : https://www.tyt888.com/?mod=download
Look for the latest version by date. When writing this article, it was : 2021-12-03
Once unzipped, the archive has 2 folders :
uv88 rep
The "Update software" folder contains a Word document with update instructions and the update software itself, UV88_98_UpData.exe.
Follow the given instructions.

The "Programming software" contains the programming software used for the frequency programming.

TYT official site
UV88 hacks page
Programming software UV-88
Operating manual