FT8 with the Yaesu FT-450D

Discussion in 'Working Different Modes' started by K7KQ, Nov 19, 2019.

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  1. K7KQ

    K7KQ Ham Member QRZ Page

    Apologies if this has been addressed. I searched but found nothing. I've been working FT8 with my FT-450D by connecting my laptop audio via the rig's 6 pin Mini DIN DATA connector on the rear panel. I plugged in small guage solid wires instead of using a proper cable like the DC11-F. I made a USB keying adapter for PTT pin 3. All works well, but I want to purchase the correct cable and Mini DIN connector to do it right. My question: Why do the commerically available data cables only have audio in and out? What about PTT? How is the rig keyed on transmit without a connection to the PTT Pin 3? Thanks
     
  2. KC3RN

    KC3RN Ham Member QRZ Page

    The 450D has a menu option for digital vox mode. That's how the rig get the "key down" signal. It's on the menu as "DIG VOX". You'll need to set the value at the threshold level you need to key the transmitter.
     
  3. K7KQ

    K7KQ Ham Member QRZ Page

    Thanks. I was wondering if it was something like that.
     
  4. KC8QVO

    KC8QVO Ham Member QRZ Page

    Just a point - VOX, whether internal to the radio or external in an audio interface (Signalink for example) is not PTT.

    PTT is a physical switch to trip the transmitter (either by closing a circuit with a push button or switch, using an electrically controlled relay or PIN diode, or a port on a radio that can receive a hot signal/positive voltage).

    VOX takes audio signal that, once it surpasses a particular gain threshold, will trigger an electronic circuit to artificially trip the PTT circuitry/function.

    The Signalink interface I referenced above is a common device. You don't set up a COM port (with RTS or DTR triggering of PTT [RS232]) because it doesn't have that ability in it. It uses the audio from the computer as an external VOX device to then trigger the PTT circuit.

    For most ham radio purposes VOX can work. It has for decades. However, it has its limitations.

    There are two circumstances that immediately come to mind:
    1. If you are using your radio with an amplifier and you want to use sequential triggering of PTT so as to put your amp in transmit mode an instant before the radio is tripped to transmit. If you rely on VOX with an audio stream you have no way to spread out the keying of the amp prior to the transmitter.

    2. If you are using receive antennas and/or preamps and have coax relays to switch the devices that are activated via PTT. You want the switches to move to the transmit positions prior to turning a transmitter on so as to not cause hot-switching. Hot-switching can arc contacts, burn out coax relays, blow out preamps, and burn up radios.

    If you are using a stand-alone radio and don't ever plan to have any of the above set ups - then VOX will work. However, do not confuse VOX activating a transceiver to transmit with true PTT function. There is a stark difference - and justifiably so. To that very point - and to the OP's question with PTT through the data jack on the FT-450 - I would be curious why there aren't commercial cables to do this. It only makes sense to have it there. For most operators that are content running VOX the addition of the PTT function to the jack won't hurt, but to those that will have a situation requiring true PTT keying - it would be a blessing and the fact that it isn't there would be a problem that would have to be overcome for proper station operation.
     

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