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.
- 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
- 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.