Internal Layout of the Yaesu FT-818

Some casual poking around the internet didn't yield any decent pictures of the inside of Yaesu's FT-818nd. I had the silly idea to try converting the rear port to Type-N like M0UKD did on an IC-7100. After some thinking, the sensible thing to do is, of course, use the 818's front BNC for VHF+ work. Before I reached that point, I decided to do a teardown to see; here are some reference pictures for the guts of the thing.


For additional resolution beyond the Blogger click-to-view image size, see my Imgur album: Yaesu FT-818nd Internal Boards

Tools: J1 bit/screwdriver (not P1, though you might get away with it). I needed a T8 to be close enough for the hex screws for my side rails.

Pop the top — definitely rotate the top cover in this direction

This is where the user servicable parts are. The roofing filter sits up behind the encoder and the TCXO module for the 817 goes just next to the shielded can of the Main Unit. The 818 has a TCXO standard and it presumably lives on the other side of the board.

Note the carefully selected placement of RF absorption material at the Head Unit cable, the trimmers near the filter, and in the shadow of the shielded can.

Main Unit overview

Main Unit power input

This is the power jack with plug detection switch. If you use a semi-permanently installed Power Pole adapter back here, the radio will keep more internal circuitry on, resulting in fairly actively draining the internal battery. To work around this, consider: not using the adapter, removing the internal battery and only using external power, or getting a third-party battery door/charger for Li-Ion that has a hard cutoff switch.

Inside the Main Unit shielded — probably best not to poke that

PA Deck overview and battery compartment

PA transistors and transformers

Output filters and selection relays at rear RF connector

Close-up of the rear UHF connector attachment to the PA board, excuse the lighting

Disconnected Head Unit

Head Unit mounting position and ribbon cable

Head Unit board overview

Production rework on the Head Unit

Population of Head Unit option resistors

Main Unit side connector bracket

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