Pimp my Yaesu

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Picture: Red charging led of battery B is glowing, indicating Pi inside rig is powered, here from internal battery on slot A. Battery selection switch acts now as power switch for Pi. Desktop of Pi is on android-tablet.


Summary: There is enough room in battery box of Yaesu FT-897 to install Raspberry Pi inside. Pi can then be used via remote desktop, for example to run PskMail software on field and use phone or tablet as user interface.
Pi 3 is used here, this model contains internal wifi-chip. Dongle on picture is USB-soundcard connected to rig's "Data in" connector. This connection is only visible hint of mod outside rig.

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Connecting regulator to input power of FT-897

FT-897 have internal relay which selects if power is taken from battery or from external DC connector. It of course shuts battery power off is external power is available. We could take power for regulator after that relay, but problem would be that Pi would not turn on with battery power if rig is off.
Therefore I have taken power from two connections, one from battery (this powering point is actually connected on the connection of orange-red wires explained below) and another powering point is near connector of external DC in (electronically connected directly to +-wire of DC-connector). These connection points are isolated from each others with two diodes. Also two 3A fuses are on powering lines before regulator.
I use 12V to 5V "buck-converter". Generally linear regulator cause less trouble with radio interference, but are wasting power. I use cheap "JTRON" regulator, stated as 3A max output power and cost about 6 euro at dx.com. Yet I have not find any trouble with interferences. Will report more later when I get more experience.
Also I have not saw interference from Pi itself. I bet key factor is that there is not much wires connected to Pi, but it is used via remote desktop.

Modification to release battery switch to be used as power switch for Pi


Yaesu FT-897 have room for two battery to be installed in "stomach". After installation of Pi, there is room left only for one internal battery inside FT-897. It is natural approach to use battery select switch as power switch for Pi.
Switch is usual two-sided rocker switch. Another side of switch chose battery, and another grounds led indicators, which turns on corresponding led on front panel, and perhaps inform processor about selection. Depending of switch position, middle terminal is connected to either one of side terminal.
I simply unsoldered wires from switch, and did some permanent connections by connecting some wires together. To make battery "A" chosen permanently, I soldered orange and red wire together (yellow is left unconnected), and blue and black (green is left unconnected).

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After modified switch connector is put back to its place, this modification left battery "A" to be chosen permanently and switch free for another use.
I have also taken power from battery to regulator from orange-red connection (that wire is not shown on these pictures).

Mod to use charge indicator led as "power on" light for pi


It seems red charge indicator led on FT-897 will illuminate when battery back sends +5 V signal on middle terminal on battery connector. This led is also independent of power state of rig, it will turn on regardless if rig is on or off. Therefore it is suitable for this use. Pi is powered with +5 V so you only have to connect same power to this middle terminal on battery connector (battery "B" connector on my case). I actually put 1k resistor here, because I think led is quite brigth and why waste power.
It seems green led could be used also, drawback is it depends of power state of rig, In other words, if rig is off, led stays off too. For me red led is anyway better, because it is warning. Pi can start transmission anytime it is on, so warning red light makes sense.

Connection between sound card and Yaesy


Connection is really simple. This is data-connector of Yaesu. Picture is from user's manual:
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And this look like sound card dongle I use with Pi. (Only I have removed case to save space).

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I have connected output from sound card (marked with little headphone symbol in sound card case) to "data in" pin throw capacitor. Capacitor value is not critical, I used o.1 uF if I remember right. (But do not use electrolytic capacitor) I have soldered connections directly to pc-board of dongle, but you can use jack connector also. Jack connector is of course stereo output. Just connect left or right to capacitor, and choose the working one on software side, whatever you use.
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I have used this also without capacitor, but I suspect it caused signal degrading on long transmission, perhaps some dc-buildup.

Sound card "mic" input is connected to "Data out 1200 Bps" pin on Yaesu. It is only wire, nothing else.

Also you need to connect ground of sound card audio connectors and Yaesu data connector ("GND") together.

On Yaesu side of cable, I took connector jack from old keyboard.

One more hint: you have to use "digital VOX" on Yaesu, not the one meant for microphone. Read user manual carefully. I bet it is done with Google translator :D It is not very clear about VOX settings or is it just my English skills...?