Youkits TJ5A

The Youkits TJ5A is now my primary transceiver. I bought it with portable operation in mind (I do not have much space for decent antennas at home). Read more for high-resolution photos.

Pros:

Very good filters (in terms of selectivity)
Built-in battery pack
20W output power (peak SSB)
Robust construction, good soldering quality, large components, will be easy to tinker :)
Light weight
Nice carry bag

Cons:

Stock speaker-mic sounds awful (as expected looking at its dimensions)
Lack of internal speaker (though I plan to install one myself)
Lack of dedicated band switch button (you have to change the tuning step to 1MHz by pressing the knob and then turn the knob to the desired band)
No interfacing, no CAT, it is a voice- and CW-only radio

Desipte lack of many features (usually taken for granted) it is a nice radio to have for an occasional operator. It is useful to have a little more power than "bare" 5W QRP transceivers have. I miss an SWR and battery level indicator the most, though the chassis has lots of free space inside (about half of the height is occupied), so I might squeeze some more electronics inside.

I looked at the control part and I have spotted an 8051 MCU that controls everything. 8051s usually have a standarized pinout. I was thinking about replacing the stock MCU with a pin-compatible part from Atmel, like ATmega162 or ATmega8535 and developing my own firmware. A couple pins are in different places, though I am not sure if they all are in use. Reverse-engineering the digital connections should not be that hard. The DDS is also a popular part.