Bluetooth PSK31/WSJT/Digital interface for Yaesu FT817 (and a tablet/PC)

I used a bluetooth CAT control with my Yaesu FT817 for quite awhile ($14 on ebay) and was generally happy with it. There is a small lag but one can get used to it. The advantage is no wires between a laptop and transceiver. Also, I could use my HP Stream tablet with it (Win 8) this way.

Given this success, I entertained an idea of making a digital (soundcard) interface wireless too. As the connection would be simplex and mono (1 channel), a regular bluetooth phone headset seemed up to the job.

I happened to have one laying around without much use so the first step was to prove the concept which was very easy. Once paired with the laptop / tablet, the headset became available as a soundcard in HRD DM780 settings. I tried sending some RTTY to it and it worked. I guess now I understand what Alexander Graham Bell felt like when his first phone worked (hi hi).

However, receiving (listening) from the headset did not work. After some googling, I found a hint – set bluetooth headset soundcard as a Default device in the Control Panel -> Sound -> Recording Devices settings. That helped right away so the next step was wiring the headset to the transceiver.

After disassembling the headset, I removed existing battery, speaker and mic and soldered new thin wires to the connecting pads.

Headset with wires

 

For TX (audio out) – I added a 1:25 resistive divider to decrease the output voltage off the speaker wires and to match the voltage requirements of Yaesu; and soldered the speakers wires to it. For RX (audio in), I needed to match Yaesu output to the headset mic. After some experimentation, a combination of two SMD capacitors to both pins and a small resistor in series to avoid overloading and to provide DC isolation finally worked.

Finally, I added a new bigger OEM Li-Ion battery (insulated with black tape) and a USB charger PCB with a switch to improve on portable operation time of the headset.

Li-Ion battery with a charger PCB

The headset, battery, charger, and the existing CAT BT control PCB all managed to fit into a small plastic enclosure. Some hot glue helped to secure them in place.

The boards sit on top of the battery / charger; to isolate the layer I cut a small sheet off a thick polyethylene water jug.

IMG_0789

The enclosure is secured with two small strips of a velcro tape. The battery can be charged via a USB connector; the switch turns on/off the bluetooth headset.

IMG_0788

The PTT is controlled by the software via the CAT control. Now to chase DX with WSJT QRP mode!

 

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QSL cards received and answered

Fresh QSL cards in the mail today – all received direct and to be confirmed direct via Canada Post mail tomorrow morning:

QSL_i2rib qsl_kd0cdm qsl_k4bll

What’s really puzzling me is that most of the QSL cards I receive recently were for digital modes. Before, most of my QSL cards came from my CW correspondents. Generally speaking, I would generally expect a modern digital mode like JT65/JT9 to be confirmed via LOTW…  Still, it’s a thrill discovering a familiar size envelope in the mailbox: it’s like a box of chocolates -you never know what you’re gonna get.

One week on JT65 on 40m

jt65_20140819

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Unattended (somewhat) JT9 / JT65 on 40m and JT-Alert

Once I had my digital interface in place, I used my new FT817ND with great success for ragchewing using PSK31, several contest-style contacts with W1AW on RTTY, and then some WSPR propagation tests, before I stumbled upon the WSJT-X app by K1JT following some questions from a ham on a local amateur radio club forum.

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Wired (and wireless) interface for digital modes for Yaesu FT-817ND

I had bought a sound card interface kit (http://foxdelta.com/products/sc2.htm) some time ago which I planned to use with soundcard-based digital modes such as PSK31 and RTTY.

Recently, I finally found time to build it and wire it to my new Yaesu FT817ND radio. Overall, it was an easy and pleasurable build – took me less than an hour. The design is very well thought and easily expandable.

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