I decided to carry out the PA1O mod for 4 meters and also install the CT1FFU preamp board, The preamp board was a very easy install.
The PA1O mod was also pretty simple and very rewarding the power is up at 85 watts now from 15 or so, It did take a bit of rummaging through the radio to get to the board to carryout the modification, once you get to the board its a case of desoldering a capacitor and thats it.
well sort of if your 847 has some transistor for controlling the ALC level on 4 (as i understand) you'll need to cut a leg off from it, mine had this transistor.
The HF and 4/6 meter final board at the top of the picture
Digging!!
During the installation of the CT1FFU preamp.
The CT1FFU board installed, its in a far more accessible location than the Power modification, I opted to attach the red + to a track that was more accessable than the one suggested (its not attached in the photo yet).
GM0USI Alan who lives close by has a 847 with a different preamp board and a different power mod. the plan is to get the radios side by side at some point and compare.