One of the challenges with the µBITx transceiver is that there is a very active community of fixers and modders. A new constructor is immediately overwhelmed by the number of postings on the BITX20 l/O Groups List or, for that matter, the number of potential fixes and mods that are available on uBITx.net.
This article is designed to communicate the fixes and mods that are likely to really matter for most constructors.
The first thing you should do is to identify which version of main board was supplied in your kit. You will see either v3 or v4 marked on your board. You will need this as there are some differences in fixes required.
Essential fix #1 – Reverse polarity fix
All constructors should provide their board with reverse voltage polarity protection and current limiter protection. The solution is simply to install a fuse (or better – two fuses, one for each of the power connections on the board) . The kit is supplied with a diode for reverse voltage protection, but this will only work if the power supply is fused, and is likely to still be inadequate if your power supply offers up 20A! See the recommended fix here.
Possible fix #2 – Audio stage issues (depending on board version and symptoms)
v3 board with WX version of TDA2822 chip
If you have a v3 board and an audio output chip marked WX, then you should read up on options for a fix. This is likely to include either replacing the WX chip with a reliable TDA2822, installing a 6v regulator on board, or using an alternative amplifier
v4 board with distorted audio
Some, but not most, v4 boards can have distorted audio. Distortion may be dependent on voltage supplied to the board. See this posting about how to fix this problem. Note that v4 boards have lower audio output that may not be suitable for driving a speaker. If you want to use a speaker chose one with 32 ohm impedance rather than a 4 or 8 ohm unit.
Essential fix #3 – Upgrade firmware
Essential fix #4 – Pop fix for constructors with v3 board
Recommended mod #5 – AGC mod from ND6T
Recommended mod #6 – Flatten power output across bands
Recommended mod #7 – Upgrade your display to a colour touch screen
Modern commercial transceivers are moving to colour touchscreens. You can have a touch screen too on your uBITx. Several options exist, but the best to date is the Nextion firmware provided by KD8CEC.
Change out your standard 16×2 display for a Nextion colour touch screen using KD8CEC firmware for both the display and the Raduino.