locked Re: WSJT-X & FTdx-5000 #txaudio #Yaesu

Chuck Moore <wd4hxg@...>


Thank you for the info on the SCU-17. I borrowed a unit from a
local and discovered the need to install the drivers before
connecting the SCU-17. Despite doing that, upon connection,
Windows immediately popped up and searched for updated
drivers, and installed them. When I go into the Device manager
there are now two new Com Ports listed (4 & 5) and when
checking to see what the audio device descriptors are in the
Sound Settings I find the apparently generic label USB Codec.
In any event I tried the rig this afternoon and successfully contacted
a couple of stations on 40 meters.  Checking PSKREPORTER
revealed dozens of stations in the Eastern US receiving my
signal with varying degrees of signal to noise. It took a while
to sort things out.

Thank you for the clarification on the audio output level on
the packet port.


Chuck WD4HXG

On August 2, 2021 at 3:52 PM, "Bill Somerville" <g4wjs@...> wrote:

On 02/08/2021 18:18, Chuck Moore via groups.io wrote:

After spending several weeks fighting with 3rd party Digital/Analog Interface boxes and
the FTdx-5000 I finally bit the bullet and pulled the scope out of mothballs to look at the
signals on the so called packet port on the FTdx5000. Some notes follow.

  • On the five pin DIN connector labeled Packet, Pin # 4, the audio out pin has about
    350 mV output unloaded.  That is with Menu Item 072, "Data Output Level"
    set to 100. As you change the Level between 0 and 100 you can see the amplitude
    change on the scope display.
  • Rear Packet Port  Audio input is blocked unless you change the stock setting on
    Menu Item 103. This item has three choices, "Front, Data & PC".  "PC" is not
    currently enabled according to Yaesu. "Front", indicates the audio input is the
    microphone connector on the front of the rig. "Data" indicates that the rear Packet
    Port Pin #1 is the audio input.  So if you use the Packet Port you must change
    Menu Item 103 to "Data".
  • Yaesu's manual indicates that the Packet Port pins for input and output are 600
    Ohm and 10 K Ohm. I suspect it is a misprint.  Insofar as I can determine the
    the input and output is 600 Ohm.
  • One thing that caused a lot of chaos for me was the lack of explanation of audio
    porting from the radio to sound devices for computers. Yaesu's SCU-17 has two
    Internal CODEC's and automagically grab audio out via the RS-232 port. Similarly
    it also injects the computer generated tones for digital modes via the RS-232
    port. Of course the CODEC's in the SCU-17 have created the digital data from
    the computer generated tones. Somehow Yaesu is routing digital  audio data
    and the CAT commands on the same USB Cable.
  • When using the Packet Port and the rig is set to either LSB or USB, the audio
    bandwidth closely matches the IF Bandwidth displayed on lower front right panel
    of the radio. Do not select the Packet Mode on the front panel, unless you are
    actually operating a packet mode. The rig narrows the IF bandwidth to about
    1000 Khz and centers the packet passband at about 1000 Hertz. For most
    common digital modes such as FT-8, PSK-31 etc you want the full IF bandwidth,
    not the narrowed packet bandwidth.
  • Beware of the terminology used in Yaesu's operating manual for the 5000 and
    SCU-17.  Of particular note it appears that Yaesu uses "Data" as a substitute
    for "Audio".  During a call with another op I asked the question if Audio and
    Data were muxed on the same pins of the Packet Connector. The answer
    seemed ambiguous and I was left even more confused.

  • Beware of Sound Devices when selecting them for WSJT in "Settings".
    Windows in its infinite wisdom seems to have a propensity for reusing names
    of devices. After attaching the SCU-17 I found four "USB Codec" entries
    instead of the two I started with.

  • Right now WSJT-X is decoding signals and I can hear the transmit audio
    via the radio's monitor provisioning.

Now I have to find out why I have a
high SWR on the low end of the HF bands.


Chuck WD4HXG

Hi Chuck,

the SCU-17 is an interface designed for Yaesu rigs with no built in sound card. It also eliminates the need for an RS-232 serial port by including a USB to serial adapter. You connect it to your rig via RS-232 to the CAT socket and via a dedicated cable for AFSK audio and PTT via the PACKET socket. There is no "interleaving" on either of those connections. The PC connection to the SCU-17 is a single USB cable, over that runs a virtual serial port protocol and a digital audio (PCM) protocol. The SCU-17 appears on your PC as a COM port, which is connected to the RS-232 output of the SCU-17, and an input and output pair of audio devices which will be given the generic name "USB Audio CODEC". The serial port will not appear unless the Yaesu VCP driver is installed on the PC. There is nothing particularly unusual about more than one protocol running in parallel over a USB connection, for example consider how a multi-port USB hub works, there are no restrictions other than power consumption as to what is connected to each hub port, yet the upstream connection is just another USB cable.

Both the DATA IN and DATA OUT pins on the packet socket of the FTdx5000 are 10 kOhm impedance. Both input and out audio on the SCU-17 are 600 Ohm impedance.


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