Programming a Yaesu FT 991A to transmit a low power carrier for tuning
Some operators uses an external tuner - and outputting a low power carrier is useful to safe and securely tune your antenna, without damaging the transceiver. But how can I output this low power carrier for tune?
There are two possible ways to make this work. One, involves the ATAS tune functionality, and the other one using the TX REQ pin on ALC jack.
Enter the radio configuration menu and change the clause 141 - TUNER SELECT from INTERNAL to ATAS.
To invoke the Carrier press and hold the mic's PTT and also push either UP or DWN buttons in PTT - while holding the PTT. To end the tune sequence, release the PTT.
By using the ATAS mode, the transceiver will output actual DC voltage to the antenna line - which is used to move the ATAS motor during the tune phase. If you have short-circuited antennas, you might risk damaging the ATAS control circuit in HF Unit thanks to the short.
Get a Stereo mini phone plug. You will be using the GND and the middle tip. Wire it to some kind of switch, pushbutton, whatever suits you better.
Connect it to the Transceiver's REM/ALC port
If you will be using an external tuner, that means that you won't be using the radio's internal tuner (doh). So, the first step is to enter the radio configuration menu and change the clause 141 - TUNER SELECT from INTERNAL to LAMP.
After everything in place, all you will have to do is push the button/switch etc that you have set to trigger the tune carrier. The transceiver will output a 10W CW tone at the tuned frequency. It will also work in VHF and UHF too.
Thanks for Norm WA4ZXV for tickling my brain and KB0ZOD for the ATAS trick.