Friday, May 23, 2008

Yaesu FT-8800 Button Mod

I recently purchased an Yaesu FT-8800R 144/430 MHz dual band FM transceiver. I wanted the dual radio feature which makes it easy to operate on one channel while checking other things on the other channel. It is two identical radios in one box.

The two complaints I have about the radio so far are that the interface buttons are all very small, which makes operating the radio while driving a little difficult, and that the tiny buttons are not backlit, which makes finding them at night next to impossible. You have to feel around on the front of the radio and hope you don't bump the 'set' button in the middle or whack either of the volume or squelch controls too hard.

I took the radio faceplate apart and found that the buttons have lots of space around them. They are suspended in a little plastic collar that allows them to float in the bezel with a gap about 1mm wide around the sides of the button. While I'm sure this gap will allow all kinds of dust into the workings, it also means any light shining behind the buttons will leak out around them.

I immediately grabbed some tools and started making. The first step was to see if the LEDs I had handy would fit:

You can see the first set of 4 LEDs on the right, they will shine through the little hole above the button support. It would probably be best to paint the area under the buttons white so the light shows up as much as possible.

Here is a closer look at one of the LEDs and the PCB material I'm using:

You can get a sense of the size of both from the millimeter scale on the ruler next to it. A smaller LED would be better, as LEDs go this one is pretty chunky and it does complicate the installation a bit. It also has contacts all the way across the bottom which requires me to install a wire for the power rather than etching it into the PCB. Double sided PCB would take care of that, but I didn't happen to have any.

Here I've cut off a piece of the board just wide enough to fit between the button posts and the edge of the display. At the ends I've trimmed it a little bit to allow for the end buttons which are placed just a bit higher than the rest.

After some work with some 600 grit sandpaper the bit of PCB just fits:

You can see how the board must be trimmed up to fit over the last buttons:

I was in a bit of a rush to get this project done so rather than setting up to etch the board I simply filed a slot through the copper. I know, lazy, but it would have taken longer to go microwave the etchant than do this. Etching would reduce the thickness of the light bar by eliminating the wire that I had to use for this installation.

Here I've started installing the LEDs. I do this by melting a thin layer of solder over where the LED will sit, then carefully placing the device. When I've got it in the right place I use the iron to melt the solder which lightly tacks down the device. I can then press it down with a finger without knocking it out of alignment and get a proper amount of solder on it.

Now I've got all 8 LEDs installed. The first one there is a little wonky, but it's close enough for a prototype. The sets of LEDs are on 10mm centers, but the two banks are offset from each other by about 0.5mm. I'm not using any resistors for this project. The docs for the LEDs say they work great without a resistor from about 2.5 to 4 volts, so I'm just going to do 2 banks of 4 in series.

Speaking of power, there has to be a way to power this thing, and I'm not sure what the power budget of the faceplate is, nor do I particularly want to start mucking about with the electronics in this thing yet, it's only a week old after all. So, rather than taking any such risk I went ahead with modifying the case. I loaded the faceplate onto the drill press and poked a few holes in it, then finished it with a file.

This is sized to hold the female part of a 2 pin header. They carry more than enough power and are small enough to be installed without making too much of a mess of the case.

I'm using some magnet wire as hookup wire. Again, very lazy, a proper installation would use wire-wrap wire or something else with proper insulation. You can see here that I'm installing the negative lead in the middle of the light bar. Ideally you'd use double-sided board and just put a via here to connect to a negative trace on the back of the board, then run that over to the end where the power leads connect. As I mentioned before this would reduce the thickness of the board by the diameter of the wire as it eliminates the requirement to run a wire all the way down to the other other end of the board.

I ran the wires around the knob on the right side of the faceplate and replaced the bit of black stuff that goes around the screen. Take care not to touch the clear screen cover or the LCD itself. It's much easier to keep them clean than it is to get them clean again. Also, the LCD seems to be particularly sensitive to touch and I suspect it would be easy to damage.

At this point I'm ready to connect the power connector and epoxy it in. Here it is read to accept the the epoxy:

Most of the epoxy goes inside to secure the connector, but some goes in the hole to make it look a bit better. Honestly, I can do better work than this, but it was pushing 5AM at this point and I just wanted to get done. I still had to be at work at 8, and I figured I could use a couple hours of sleep at least.

The power connector is just a 12v automotive power adapter that I cut
in half and connected to the header and insulated with some heat shrink

I wanted to use red LEDs to go with the amber faceplate, but I could not find any until I was finished. I may go ahead and make a second version using the red LEDs. This time I'll try putting them under the buttons instead of above.

Here is a blurry picture of the result. Obviously you cannot read the captions on the buttons, but I don't really need to, the text is so small I can't usually read it while I'm driving anyway. The point is to make the buttons visible without requiring a lamp or having to feel around in the dark. This meets the requirement nicely I think.

You can see that the right-most button is not well lit. I think the LED over there is offset a little too much and doesn't shine through the little hole over the button very well. It is brighter than it looks here, but it is dim enough to be visually unappealing.

The biggest problem is that the thickness of the light bar restricts the movement of the buttons a bit which makes it hard to push a few of them. In particular the scan button on the right is very stiff. Functionally this isn't a problem because with some effort they do work and I can use the soft buttons on the mic (which also aren't lit!) to access all of those functions. It is annoying though, and it offends my sense of proper workmanship.

I consider this a failed project because it reduces the quality of some elements of the original project. I believe though that the idea is good and that I can product another version that will work as intended. And it'll be red instead of blue.

I think that a better way to do this modification would be to remove the buttons and fabricate a new set using clear plastic. This would allow for proper back-lighting as found on some of Yaesu's other radios. If I could get a spare face plate to work with I'd be willing to develop the buttons necessary to do this, but Yaesu's website doesn't list a price for a replacement faceplate.
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