Table of Contents
Yaesu FT-450D
160m to 6m with ATU capable of matching 3:1, 100W. RS232 CAT control. 6 pin mini DIN data port. Easily modified for RF or IF output to an SDR using a HupRF board.
TNC cable
| Pin | Use | NinoTNC / Kantronics pin |
| 1 | TX audio | 1 |
| 2 | Ground | 6 |
| 3 | PTT | 3 |
| 5 | RX audio | 5 |
A suitable cable can be made from a PS/2 extension lead, scrap PS/2 mouse or keyboard. Sometimes with the mouse/keyboard option, not all of the required pins are populated, so may not be suitable. Identify the pins with a multimeter (a croc clip lead is useful here.) Solder a DB9 plug on to the other end as above.
Usage with NinoTNC
The Yaesu FT-450D works well with the NinoTNC but requires some audio isolation between the TNC and the radio in some circumstances. This can manifest as wideband noise on transmit. Discussion was had here.
Full isolation (including PTT) does not appear to be required - simply cut the ground and TX audio lines in your radio-TNC cable and insert an audio transformer between them. Ensure there is a ground path for the PTT line - in my case, using a Pi with a 12V-5V DC-DC converter, it was sufficient to ensure that the negative side of the input and the output of the DC-DC converter were common.
Detail of audio isolation:
Previously there was an article here involving a full isolation circuit with relay powered by DC brought out from the TNC, but this has proven to not be necessary.
Errata
M0GZP has found, empirically, that both the input and output pins should perhaps be documented at 60mV instead of 500mV. This is why the NinoTNC SIGNALS settings of 0000 works for this radio, which is unexpected.