Yaesu FT-450D Transceiver

  • USB-to-DB9 cable installed to the CAT interface
  • Computer runs the ADMS-450 channel-programming program fine.
  • Computer can run the PCC remote-control program fine.

DATA connector has these pins:

enter image description here

And the cable looks like this:

enter image description here

  • DATA connector is attached to the computer's audio in/out jacks
  • Computer can record receive-audio fine.

The Operator's Manual shows an external TNC for RTTY and PSK, wired like this:

enter image description here

So I admit to being a bit confused as I thought the data cable would be all that would be necessary to use software digital modes from the laptop. Now I see that the PTT line is n/c.

It does function as a very good analog interface, and makes good recordings.

The goal is to use the laptop as a CW keyboard and memory keyer.

Perhaps the simplest option would be to use the Keyer jack directly with a Python program on a RPi3B from the junk box.

If it is possible to do it with the existing connections that would be best.

In searching around with Google there seems to be very little information about doing this.

QUESTION: How to use the FT-450D for CW from the computer?

How do you key the carrier remotely? Is it possible to use the CAT interface to send CW?

  • $\begingroup$ I have a question. The CAT Operation manual shows commands for the Mic Up and Down buttons, which can be used as Dot and Dash with the built-in electronic keyer. Is there a program or function as part of a rig control to convert text to commands to key these buttons and utilize this keyer directly without extra devices (other than the PC.) Just a thought. $\endgroup$
    – odonusa007
    Commented Sep 14, 2018 at 19:46
  • $\begingroup$ @odonusa007 You may want to ask a separate question about this. $\endgroup$ Commented Sep 14, 2018 at 20:37

1 Answer 1


The "data" cable you picture provides only audio in and out. Some other device, like a TNC or a computer, must provide the modulation and demodulation to provide any data capability.

Additionally, the cable picture does not expose the PTT connection on the data port, so with that cable alone there's no way for the computer to key the transmitter.

However, you do say you have a "USB-to-DB9 cable" installed. Yaesu calls this the CAT port. You can use this connection to key the transmitter, as well as control most other functions of the radio such as frequency, mode, and so on.

It sounds like all you need to do is configure your CW keyer software to use the CAT interface to control the radio.

How this is done depends on the software, but any reasonably modern software like fldigi or Ham Radio Deluxe does have the capability. Look through the setup menus and you should be able to find it.

  • $\begingroup$ For digital modes that kind of software makes sense, and thank you for those names, because that will be next on my list. Upvote. Today I want to focus on CW, both sending and recording/decoding. This data cable will help with the receiving part, so I now want the ability to type-to-CW, or at least have CW memory, (and perhaps the ability to transmit CW practice on 80 for the locals), even if I have to program it myself. The new question should perhaps be: What signals need to be sent via CAT to trigger PTT? $\endgroup$
    – SDsolar
    Commented May 28, 2018 at 20:40
  • 1
    $\begingroup$ @SDsolar If you want to manipulate CAT on a Pi (or any Linux, and I think Windows too) you probably want to use hamlib, or its command-line interface, rigctl. Many programs (including fldigi) link to hamlib to implement the rig control under the hood. $\endgroup$ Commented May 28, 2018 at 23:34
  • $\begingroup$ That's great. Will look for those. Here's a question: Suppose I could isolate that PTT pin by building my own interface. I would suppose the best assumption would be that PTT-to-GND would switch on the carrier like a traditional TAPR-2 TNC, eh? $\endgroup$
    – SDsolar
    Commented May 29, 2018 at 16:32
  • $\begingroup$ @SDsolar For FM and SSB modes it should have the same effect as the microphone PTT. I don't know what it would do in CW mode. When I operate CW with my computer I leave the radio in USB and let the computer generate the carrier. $\endgroup$ Commented May 29, 2018 at 16:48
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    $\begingroup$ @SDsolar That relay is based on a phototriac so it won't release until the current drops to zero. It's made for switching AC loads only. For a keyer you probably don't even need an SSR: a simple open-collector or open-drain output would work. $\endgroup$ Commented Jun 7, 2018 at 11:25

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