While I have no financial interest in MTS, suffice to say that I have known Keith, G4FUF and Ian, G4EZP for a year or several. They had mentioned plans for this project once or twice and when the first boards/kits were produced both G4ZTR and I jumped at the chance of trying it out.
Briefly, the board is fairly simple, but uses SMD components where appropriate and requires certain surgery on your '847. That said, it is all reversible if you can't bear the transformation of the 4M side of your wireless into a quiet, high-gain 4 Metre receiver.Here are the key features:
70MHz Low Noise amplifier -typically 20dB gain, noise figure<1dB
High Pass Filter - when the LNA is bypassed this board duplicates the HPF function of the original Yaesu daughter board modification.
The board is specifically designed for mounting within the FT-847 but may be used externally.
I'm not going in to detail: here are some pictures...