SDC Datamodes on MacoS

[Rich G4ZFE]

I am a new Flex and SDC convert (since January). I have been using SDC on Windows 11 with a Flex 6300 since then. Everything works - Skimmer, CW, RTTY and PSK63. All my contests this year have been using SDC. SDC is an amazing suite of software and it has renewed my interest in contesting. Thank you Yuri!

As my Windows PC is a general PC running VMs and vibe coding with Claude I wanted to move my contest software to a new machine. I selected a Mac Mini M4 base.

I have installed SmartSDR for macOS, AetherSDR for macOS (not installed the DAX as not needed) and SDC macOS M.

SDC and AetherSDR/SmartSDR work great in CW on my mac. My issue is RTTY and PSK63 on mac. Using SDC Digi (and SDC contest e.g Volta RTTY last weekend) I can receive RTTY OK, TX enables TX on the Flex but no RTTY/PSK tones and no RF output. I am puzzled as I have this working well on Windows.

I used the RTTY program in macOS SmartSDR (using DAX) and that sends RTTY OK.

SDC version 19.0609   (works OK on Windows for RTTY)
AetherSDR 26.5.1     (works OK on Windows for RTTY)
macOS Tahoe 26.4.1

As a new Mac user is there some additional software I am missing? Does anyone have this combo working?

73 de Rich, G4ZFE

[UT4LW Yuri Pavlov]

Rich, if you're using macOS and AetherSDR, make sure to launch SDC after starting the transceiver software. I haven't yet identified the issue causing SDC to crash during transmission, but launching the programs in this order resolves the problem. Do not use DAX for SmartSDR or similar systems in other software, as they may hijack the DAX API.

[Rich G4ZFE]

Hello Yuri,

Thank you for the reply.

I am starting AetherSDR/SmartSDR for macOS first and then starting SDC.
No DAX involved. I didn't install the macOS DAX drivers that comes with AetherSDR.

Just using SmartSDR API which is why I like SDC so much.

I enabled SmartSDR API trace on the TCP channel and I can a difference in behaviour between MacOS and Windows.
My test was to enable trace, start RTTY modem in Digi Server and transmit a short test message.
Mac - Flex goes to TX, no RF generated (Flex returns tx=0)

> C21|stream create type=dax_tx
- setIqStart:0/True/0x758bb0000|False
- mIqStart: 0/0
< S7C32C940|stream 0x84000002 type=dax_tx client_handle=0x7C32C940 tx=0 ip=192.168.1.139
R21|0|84000002

Windows -Flex goes to TX, RTTY tones generated and all good.  I see Flex returns tx=1
> C21|stream create type=dax_tx
- setIqStart:0/True/0x27a5c541020|False
- mIqStart: 0/0
< S71ABD2DE|stream 0x84000001 type=dax_tx client_handle=0x71ABD2DE tx=1 ip=192.168.1.83
R21|0|84000001

I will wait to see if I get any feedback from other macOS users who use RTTY.  I am sure there are other users on same version of macOS (26.4.1)

I am sure that as a new macOS user I am doing something wrong but I hope one of the macOS users will be able to assist!

73 de Rich, G4ZFE

[UT4LW Yuri Pavlov]

Rich, that's strange behavior for the program. What version of SmartSDR firmware is installed on the transceiver?

Try this version of SDC.

среда, 13 мая 2026 г. в 00:28:01 UTC+3, Rich G4ZFE:

[Rich G4ZFE]

Hello Yuri,

Many thanks! The new SDC build fixed my issue. I have RTTY working now on macOS using AetherSDR and SmartSDR for Mac.

My Flex 6300 is on 4.2.18

Thank you for the amazing support!

73 de Rich, G4ZFE