Integrating Digirig with Hardrock-50 Amp and Xiegu G90

My Xiegu G90 has been happily cooperating with the Digirig for a year or two. Now I have built the Hardrock-50, a 50-watt amplifier in kit form. I want to add the optional Hardrock ATU which requires a band-specific voltage from the G90 to automatically set the band. The Hardrock-50/ATU supports this via a DB9 serial port.

However, the G90 ports needed are already used by the Digirig. Has anyone already faced this issue and come up with an elegant solution? Is it as simple as making up a Y-cable where the signals need to go to both the Digirig and the Hardrock-50? Both want to use the 3.5mm CAT port on the side of the G90. Or can I open up the Digirig and tap into the signal line there?

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Do you know if the amp is just listening to the band/vfo updates on the serial line or also talks to the transceiver? It would be easy to implement the “Y” splitter as long as two devices are not trying to TXD to the same line. As and experiment I’d try connecting the amp with just ground and RXD line (transceiver’s TXD) and see if that works.

Thanks, I’ll try the experiment to make sure but I don’t think the amp sends info back to the transceiver. As a separate issue/activity, there is also a Raspberry Pi controlling the digital radio software, and via this little computer I plan to write some Python to display the amplifier’s status – it supports some basic serial commands (GET/SET’s). But for that I’ll be using the Pi’s USB port.

Only things I am still wondering about if is the amp’s input is expecting serial voltages or logic voltages. I’m researching that on the side. Also the requirements of the 3.5mm plug – does the Xiegu expect a TRRS or just a TRS plug?

Xiegu’s head unit uses logic levels serial (3.3V) and uses TRS connector (pinout is in manual).
Please keep us posted about your experimentations.

Someone suggested I try the Xiegu CE-19 interface, which apparently breaks out various signals from the 8-pin Xiegu rear ACC socket into separate 3.5mm and MINIDIN connectors. I tried connecting the Digirig MINIDIN-8pin to the output from the CE-19 (specifically the output labeled “To XPA125”) but by doing this I lost the audio signal to the Raspberry Pi running WSJTX. (I think…the symptom is no FT8 signals reaching the WSJTX software. I believe this is only audio info but may be wrong about that.) The Hardrock-50 amp did begin receiving the band control voltages from the G90 though. So one step forward but another back.

Of course the Digirig MINIDIN-8 was included with my Digirig by special request, so perhaps I need to replace this connector with the MINIDIN-6 connector on the CE-19 board?

CE-19 does break out signals, but it uses 3.5mm TRS jacks for audio so you’ll need a different cable get audio back together into Digirig’s single 3.5mm TRRS connector. Faced with the custom build in one place or the other my personal preference would be to make a MiniDin8 Y-splitter, get rid of CE-19 while using stock cables.

I hunted the usual parts suppliers in the US (Mouser, Gigaparts, Amazon) but didn’t find an 8-pin Mini DIN splitter cable with the right pin configuration. Do you (K0TX) supply such a thing? What would be the cost with shipment to USA?

I’ll consider designing/ordering a batch of these Y-splitters. Please stay tuned for the update via the mailing list. Until then you can go with a homebrew build. I see suitable connectors available on ebay.

Yes, the connectors are available, but not a premade Y splitter cable.

If I may suggest, when designing/ordering a Y splitter cable, please keep the leads short and straight, not coiled. 6 inch lead length should be plenty in my opinion.

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