Javier Albinarrate - LU8AJA

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Yaesu FC-1000 Automatic Antenna Tuner


This is a short comment on some information I gathered that might be usefull to others and that it is not in the Internet.

While I was integrating the FC-1000 into my Enhanced CAT, I gave a brief look to the "DATA" line of the connector which connects the inhouse unit with the exterior unit. This lead to some interesting (although I doubt they are usefull) discoveries on the protocol between the outdoor and the indoor units.

Also, I wrote a small set of tips about connecting the FC-1000 to other transceivers, any brand and model.

Serial Protocol 

It turns out to be a 300bps asyncronous 5Volts communication.

I made a few quick changes to my CAT to actually read it, and I got these data streams:

Reset button    
 11111111 00111100 11101111 11111111
 FF       3C       EF       FF

Thru button
 11111111 01011101 11111111 11111111 01011101 11111111 11111111 01101101 11111111 11111111
 FF       5D       FF       FF       5D       FF       FF       6D       FF       FF

Start button
 11111111 01011110 11101111 11111111 01011110 11101111 11111111
 FF       5E       EF       FF       5E       EF       FF      EF FF
 Pause while tuning...
 01101110 11111111 11111111
 6E       FF       FF

I am not even sure if this communication is bidirectional, perhaps I'll verify that soon, right now I have no time.

I don't really need this as I am not getting connected to that line, but if somebody knows how these commands should be interpreted I'd appreciate any help.


Using the FC-1000 with other transceivers

In a few posts on the Internet I found people saying that without the BAND data cable, you cannot use this AAT. This is not really the case, the BAND information is used to automatically change the memories of the AAT, but if you don't have that cable, as in my case, you just have to repeat the simple matching proccess every time you change bands. So there is no big deal, just change the mode to CW, the drive to about 5 to 10 watts and push the start button.

Now, having said that about the BAND DATA cable, lets see how about the other signals (I was recently asked how could this AAT be used with other rigs, not only Yaesu).


Updated 2008-09-02 11:45:50 

Update on BAND DATA: Thanks to Dave G8KBV, because he has confirmed what I mention here, about the band data lines. Whatever 4 bit signal (5 Volts) you provide, it will work as a memory. He has used other rigs with 4 lines (like TS-870), and also he has used a PIC, and simple switches as well. With 4 bits, you have 16 memories, you can handle with 4 SPST switches and 4 resistances (pull-up or pull-down, whatever you wish). Of course, you have to somehow remember the memories. If you don't want to make things complicated, then just use the 4 SPST switches, and by switching just one of them at a time you can have 4 easy to handle memories. One important note, if you are going to connect whatever to these lines, remember they are 5V! Be extremely sure what voltage is providing your rig. 


Updated 2008-08-21 17:18:53

If you correctly connect the outdoor unit with the indor unit, and you setup the required signals between the rig and the AAT, and you put the rig in CW at arround 5 Watts, it MUST work, no matter what brand/model you have. If it doesn't, then there is something wrong in your setup.

These are the signals at the back of the FC-1000:

  • PTT is obviously required, so the AAT can start a transmission when you press the "Start" button. It is the standard PTT (AAT will pull this to GND when transmitting). In some transceivers, you have the PTT, in others it is called differently (TX to GND). Also in some rigs, there is a speciffic PTT to be used by the AAT which will automatically switch to CW (which is a requirement).
  • ALC is required, because is used by the AAT to control the output of the rig, otherwise the output stage could be fried in theory.
  • 13.5 Volts is not required. It is used so the AAT knows when the TRX is on/off, but you can use it from another source, and manually switch it on/off.
  • Band data is not required. It is just used by the AAT to know what memory use, if you don't connect it, you MUST always match the AAT before starting a transmission in a new band.


  • Read your rig manual. Also the manual for the FC-1000. If you don't have them, search the Internet, or ask somebody.
  • Make sure you have correctly connected the outdoor unit to the indoor unit
  • ALWAYS setup the rig in a CW mode when you match the AAT, because it will not work without a carrier (like in SSB). Some rigs, have a special PTT for the AAT which automatically switches to CW.
  • Drive the rig between 5 to 10 Watts, never more than that.
  • If you don't have BAND DATA connected, don't trust the green LED of the FC-1000, ALWAYS match the AAT whenever you change your band.
  • IMPORTANT: Remember to change the 3V battery in the outdoor unit, before placing it in a tall mast :) this has happened to me...

Example: Connecting FC-1000 to a Yaesu FT-857D

I found the manual here (PDF 3.3 Mb)

In pages 32 and 33 you have a description of the connectors
The important one, is number 4, the ACC connector. In that connector you have both ALC and PTT (TX GND).
The other one, the linear connector, has the A, B, C, D band data pins, as you already know they are optional.
Finally, according to the manual, if you use the PTT in the ACC connector, the transceiver automatically switched to CW, so you don't have to take care of that.
Give it a read page 33, connector "4 ACC".



Example: Connecting FC-1000 to a Kenwood TS-140

You have the manual available here (DjVu 1.53Mb) You have a DjVu (something like a free PDF) viewer here.

If you find a broken link please email me.

Pages 14 and 15 have the connectors.
The required signals "ALC In" and PTT are both available in the "Remote" connector.
This transceiver has also a connector named ACC3 which is specifically for an automatic antenna tuner.
Unfortunately I don't see any specs about its pins... after looking at the schematics I have I think the ALC In and PTT are not available in this connector, but the schematics are in a ver poor condition.
But I think, the ACC3 connector has the BAND DATA (ABCD) signals available.
Even if the codes in the Band Data are different from the ones that Yaesu uses, I really think that does not matter. Because I think that the AAT only uses that for selecting a memory, so there wouldn't be any difference in having different codes.
But again, connect them at your own risk, if you cause a nuclear meltdown, or World War III by connecting those signals, don't blame me.


Last Updated on Sunday, 08 March 2009 00:33  

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