EME Hacks

How to make your first EME contact using Remote Ham Radio – Part 1

Setting up your Laptop

STEP 1: Install xCAT and the RHR app

Download and install both xCAT and RHR. You are not going to add any configurations until it will be time to use them.

STEP 2: Install the Blackhole Audio driver

An audio driver application is needed in order to route audio feeds between different applications. Blackhole is an open source driver that is very easy to install or remove.
To install, you can either download the installer or – if you already have it – you can use Homebrew with this command:

brew install blackhole-2ch

Note: The authors would love if you could donate $10 to their project, but that isn’t strictly necessary.
The 2 Channels version is just perfect for this application so there is no need to use their 16 or 64 channels versions.

Either way, at this point a new Audio Device one called “Blackhole 2ch” will appear:

A “BlacHole 2ch” virtual device appears after installing the Blackhole Audio Device.

STEP 3: Create a Multi-Audio Device

A Multi-Audio Device is useful in order to listen in as you either receive or transmit. To create it, open “Audio MIDI Setup” (it’s inside the “Utilities” folder) then create the device by clicking on +:

Select + then choose “Create Multi-Output Device”

Within the newly created device activate both the Speakers and the Blackhole devices:

Our Multi-Output Device needs to include both the Speakers and the Virtual Device.

Now yet another audio device – called “Multi-Audio Device” will appear in the list:

Multi-Output Device appears in the list of active Audio devices and is ready to be used.

Note: The Multi-Audio device could be omitted if you decide that you don’t want to monitor any audio. If that is OK with you, just replace the below mentions of it with “Blackhole 2ch”.

STEP 4: Install WSJT-X

If you don’t already use WSJT-X for Mac you will need to install it. Just download it and follow their instructions.
There is however one trick I’d like to share: if you want to avoid modifying your system configuration you can run the following command in a terminal window right before you use the program:

sudo  sysctl  -w  kern.sysv.shmmax=104857600; sudo sysctl  -w  kern.sysv.shmall=25600

That will allow you to run it until you eventually reboot. No changes necessary!

STEP 5: Create an EME specific WSJT-X configuration

The WSJT-X settings needed for EME work are different from the usual ones and probably deserve their own configuration. Here is mine:

The Gridsquare you declare needs to be one where the transmitting antennas are (Jefferson is in FN22) and NOT where you are with your laptop. Don’t forget to activate the Decoding EME delay.
The rig (a FlexRadio) connects to the RHR application. In turn, the xCAT program connects to the RHR application. WSJT-X connects to xCAT which runs locally on port 5002.
Note that the Output Audio is sent to the Multi-Output Device. That allows you to listen your transmitted audio as transmission happens.

STEP 6: Setup RHR

When you launch RHR for the first time the application will ask for your Remote Ham Radio account username and password. After that, you will be presented with a screen where you can select the station you want to use. Go ahead and select W2/Jefferson from the list (Relax: you are not paying anything yet).

On the upper right corner of the window, click on the headphones icon and select the audio devices we just created: Blackhole for the Mic and Multi-Output Device for the Speakers. This is what you need to see:

Select “Blackhole 2ch” as the Microphone and “Multi-Output Device” as the Speaker devices.

Now click “Connect”. Beware that from this point on the clock starts running and will be charged by RHR according to how long you will use the station.

Please note the following:

  • if when you connect FT8 is the selected mode then you must manually change it to DIGU (or USB, doesn’t matter as long as it is not FT8). You will not be able to use WSJT-X otherwise.
  • Make sure “TX DAX” is set to ON
  • In VHF it is perfectly normal to see a noise-floor around S5 or S6
  • Do not forget to activate “Track Moon

This is what the station should look like in the app:

Jefferson is receiving on 144.123 MHz USB with all the parameters correctly set

STEP 7: Launch and connect xCAT

Now launch xCAT.
You will be presented with a Window where you will need to double click on the station you want to connect to. There will only be one entry in the list so you can’t miss it: just click W2/Jefferson:

Simply click on W2/Jefferson in order to start using xCAT

After you select the station xCA is already active and ready to be used. You are free to minimize or hide it as you won’t need to look at it anymore:

xCAT is up and running

Note: using xCAT could theoretically be avoided if one were to renounce Radio control and use VOX as PTT method.

STEP 8: Verify WSJT-X can transmit

Open WSJT-X and make sure you select the same configuration created in Step 5. Select “Tune” and check if the amplifier is transmitting around 750W:

When transmitting the WSJT-X test note a power output of about 750-800W should be observed.

That’s it! You are ready to rock and roll.

What’s next?

Doing the actual EME contact is complex enough to require a dedicated post. In Part 2 I will try describe the operational aspects of it so you can avoid the mistakes I already made.