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

Comments

Post a Comment

Popular posts from this blog

Hardware Filter Modifications for Quansheng UV-K5 Band Extensions?

The Quansheng UV-K5 ( product page archive ) handheld transceiver has been notable in cheap amateur radios of 2023 by using both a wideband FM chip BK4819 ( product page archive ). With support of 18-620 and 840-1200 MHz half-duplex with 6.25/12.5/20/25 kHz channel spacing, this puts the chip in the range of five ITU Region 2 amateur bands (10m, 6m, 2m, 1.25m, 70cm, 33 cm) and spitting distance from a sixth (23 cm). Presumably hitting 4m and the rare 8m would be within reason as well. The easily hackable firmware indicates at least nominal receive capability up to 1300 MHz, though!
Read more

MEAN WELL HLG-320H Power Supply Actual Teardown and Failure Investigation

Image
Last left off in the preview "teardown" despairing over the potting was my failed MEAN WELL HLG-320H. Then came a great need for mindless stimulation after a day of work and I tried cracking the case again. After the successful prying came picking and cutting away at the potting material to see what's what. Here's what's inside! Image warning: there's a lot to get through this whole device. Click on the photo for the full Blogger resolution. There you go, just a bit more force and the top plate comes off.
Read more

Too Much in One Day: POTA, SOTA, Wisconsin QSO Party (K-1441 and K9/WI-010, then K-4238)

Image
With all the prep done over in the other post and acceptable weather, of course I had to actually take on the adventure. My drive out to K-1441 Blue Mound State Park ( wiki ) was a little on the late side. Stopping in Verona on the way over to acquire some fast food to maintain energy through the event also put me a bit further behind schedule. Soon enough, I arrived at the middle altitude parking lot of the park to hike the rest of the way to summit W9/WI-010 all in Iowa county. Only a bit into the 1800Z March 13th start, but there's still setup and making contacts to happen. View up the trail from just above the parking lot to reach the East Tower on the summit
Read more