How I ran FT8 III

In the first article series I described the interface (interface) pre TCVR Kenwood TS-870S, which added another mode to our HAM family. To be continued article pre TCVR Yaesu FT-817ND. The connections work reliably, FT8's collection of diplomas is growing incredibly. You can see the most beautiful ones in photo album. The construction of your own digi interface is really undemanding and affordable. For Paľa, OM7ASP I made an even simpler version of the digi interface for its TCVR Yaesu FT-857D, which I will describe to you now.

Construction

The wiring diagram is basically the same as in the second part, therefore, I will no longer describe it here. You may be wondering what the difference is. The answer is simple. No need to look for a box. You can use the one from the USB hub. He worked for me 4 USB port hub from Hama. It has enough space for audio circuits after flying out one USB connector (A picture 1). Welding requires a little skill. Two carpet knives have worked for me, because they are also quite thin, also quite solid. Carefully insert one into the gap between the cover and the base, and slowly and gently pry the gap around the perimeter until we release all the latches.. The cover should fall out by itself (A picture 2). We'll fly you one USB connector - a USB sound card board will be fixed in its place. We solder briefly at temperature 180 – 200 °C.

A picture 1 Covered 4 USB port hub
A picture 1 Covered 4 USB port hub

 

A picture 2 Open USB hub
A picture 2 Open USB hub

We will choose the same model of the USB sound card as the previous part, just any card from a Chinese store is enough. We remove the cover much easier (A picture 3).

A picture 3 A look at an exposed USB sound card
A picture 3 A look at an exposed USB sound card

We fly out of the card a USB male connector and two jack connectors for a microphone and headphones. Let me warn you again, to be careful when soldering, there is a risk of the printed circuit board being burned out or the paths with the connections being torn off. We connect soldered contacts via USB connectors with flexible cables. We determine their length when attaching the USB sound card to the USB hub. The plates should fit together, take up as little space as possible and, in particular, their components must not touch, so as not to damage them. Probably no one wants to fly back the SMD capacitor. When the plates are fitted, cables measured and cut to the correct length, we can fly them. Let's try, whether the plates fit into the box, not to protrude.

Next comes the introduction of audio paths to the TCVR. This is achieved via a 6-pin DATA connector. We will choose a fairly long shielded audio cable. With one wire for audio input, the second for audio output and the third for grounding. Connect the wires on the connector side with the DATA IN pins, DATA OUT a GND. We pass the cable through the hole after the soldered USB connector from the USB hub. We can previously push a strip of plastic foil onto the cable from outside and inside the box, so that the opening is well closed.

We fly DATA OUT 1200bps through a 1k2 Ω resistor to the microphone input. She is indifferent, which channel to select, because the microphone has them connected.

DATA IN is first connected via a 3k3 Ω resistor to the speaker output (either right or left). Finally we connect DATA IN via a resistor 100 Ω and GND.

Finally we connect GND from TCVR to GND USB sound card. We adjust the position of the resistors in this way, to take up as little space as possible. We help each other with tubes, so that there is no short circuit.

I recommend trying the connection first without the cover in order to correct any shortcomings.

A picture 4 Interface before covering
A picture 4 Interface before covering

 

A picture 5 Finished interface with connected CAT cable
A picture 5 Finished interface with connected CAT cable

 

A picture 6 Connection to TCVR - Front view
A picture 6 Connection to TCVR – Front view

 

A picture 7  Connection to TCVR - View from the top
A picture 7 Connection to TCVR – View from the top

When everything works, we can close the box. We're done. Have fun broadcasting.

Digimode Software Setup Guide

How to set up Windows operating system 10 and WSJT-X is in this video:

Resources

How I ran FT8

How I ran FT8 II

How to control CW via computer

 

Martin Jánoš, OM1MJ

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