EME – K1FM.us

How to make your first EME contact using Remote Ham Radio – Part 2

In part 1 I have described how to setup your RHR account your Mac in order to try EME contacts. This time I will explain some of the operational challenges that you need to understand in order to be successful.

Be advised that I am far from being an expert. In fact I am precisely the opposite as, at the time of this writing, I have logged a total of just 8 valid EME contacts. Still I believe this might be useful to some: If made an EME contact, so can you!

Finding the Moon

This might be unsurprising but in order to do EME contacts you need the moon to be visible. Having no Moon in the sky feels exactly like having no propagation on 20 meters. You just have to wait.

Some great tools to predict Moon visibility are mooncalc.org and timeanddate.com.

Both website are useful to determine the Moon direction and elevation as well as its distance from the Earth. Distance plays a big role in this: having the Moon at “just” 360000 Kilometers is much better than having it at 405000 Kilometers, for obvious reasons. More simply, you might end up using those sites (or similar others) to predict when the Moon availability is compatible with schedule.

Please note that WSJT-X can display some of the same info within its “Astronomical Data” window however I still like to use these websites as I find them more accessible and useful.

Mooncalc.org is useful to display realtime Moon parameters.

Timeanddate.org’s Table function can be used to predict Moonrise/Moonset times as well as Moon Distance.

Pinging the Moon

Before you go into action – especially if it is your very first attempt – you might want verify if you can receive your own echos bouncing off the Moon.

Doing this test is relatively easy as WSJT-X has a specific mode called “Echo” just for that purpose. The documentation goes in depth in explaining how the mode works so you can refer to it.

In a nutshell: with your station ready to go on a clear frequency, select the “Echo” mode and click on “Enable TX”. Pinging will begin immediately. VHF does not require Doppler correction at the Rig level so you cal leave Doppler Tracking on the Astronomical Data Window unchecked.

Here is a successful example:

As per the documentation, the reply quality is represented in the Q column on a scale from 0 (no echo) to 10 (perfect echo).

Echos won’t always come back from the moon. That might indicate a problem with your setup (is power being actually transmitted? is the antenna pointed towards the moon? is the RX chain working properly? the list could be long…) or it could also indicate – as they say – poor “Moon conditions“.

Introduction

Ever since I embarked on my journey in Amateur Radio, I have always regarded EME as the pinnacle of the hobby. The concept of bouncing signals off the Moon held a tremendous allure, but the immense distance, substantial link budget, and the requirement for massive antennas made it seem completely unattainable.

However, over the years, moonbounce has become increasingly accessible. The proliferation of digital modes has enabled ordinary hams to achieve Earth-Moon-Earth contacts even with relatively modest setups. You no longer need an antenna that would grace the front cover of a magazine to engage with the moon.

More recently Remote Ham Radio mada available a quite decent EME station for anyone to utilize. Consequently, if you wish to try EME today, all you need is your laptop. Pretty neat, isn’t it?

Before we move on, let me clarify two things:

This is intended for Mac users. If you use Windows… I’m sorry!

Remote Ham Radio isn’t sponsoring me in any way. I actually paid with my own money in order to use their service and research its functionalities. But… hey I did for science so that’s OK. I also did for fun. Actually, I did it just for fun. Whatever… let’s get into it!

Cost

Remote Ham Radio is a company that offers some kind of an “Amateur Radio as a Service” model. The concept is simple: they build powerful stations and you paid to use them. One of their stations – called Jefferson – is EME VHF capable.

Jefferson has an array of 4×16 elements Yagis and a 1KW amplifier. This is far from being a Big Gun in the world of EME, but is definitely enough to make a lot of contacts. Using the station currently costs $0.79 per minute + membership fee ($99 per year or $20 per month) . As you can see this isn’t cheap but it is still certainly cheaper than building your own station from nothing.

What you will need

Unfortunately RHR’s documentation about EME isn’t super descriptive. In the process of learning how to use their station I ended up with a setup that is a bit different. I find mine to be more convenient for the simple reason that it doesn’t require you to alter your Mac’s default security settings. Also, you will not need to pay extra $99 in order to purchase a third party program (see below).

This is what you are going to need:

Contrary to what RHR recommends, in my setup you DON’T NEED:

~~Amoeba Loopback~~ ($99)

~~xDAX by DL3LSM~~