I'm interested in giving EME a shot but am not sure of the entry level requirments for this.
Would an IC7000 and two crossed 9 element Yagi's be a good starting point.
My club had two long time EME'ers give us a talk a two years ago. They tossed out the rule of thumb of "10-1000". A 10 element long john yagi, and 1000 watts should be considered a minimum.
Author of: Mr. Fred, Nuke This Forum (Danger Close)
Here is a tutorial on doing it with the digital mode JT65b--you may have enough for this mode if your feedline is short and you have a location that can optimally use ground gain to get to other stations.
The moon is a lot closer on Wednesdays.
TOM K8ERV Montrose Colo
It sounds like you have a good starting point. I have heard of folks running EME with a few hundred watts and a single yagi with JT-65B mode. They might be working the bigger stations, but it's still EME. I'm new to EME myself, I've worked maybe 20 or 30 QSO's so far with 4 homebrew yagis and an amp on 2 meters. I don't have it, but I understand cross polarization comes in handy at times.
You'll probably want to find an amp of some sort of at least a couple of hundred watts. Other things to take into consideration are very low loss coax, mast mounted pre-amps, etc. Every little bit helps.
Making that first QSO makes all the effort worth it. It's something to be proud of!
Thanks for the feedback guys.
It seems that EME can be done with a smallish antenna array. The crossed yagi's will be polarization switchable, they are being built primarily for satellites.
Hello, google EME QRP and you will find many that do it. You will need the other guy to do the heavy lifting but it can be done. What is hard to do is EME QRP on BOTH ends.
One route I have not seen mentioned is to go to Ping Jockey Central. On there at top you will see jt65 mentioned; if you follow that you will get to their EME section. Check with some of the guys there that are doing it and see what they reccomend. I have done EME with a 150W Mirage amp and a 12el yagi and an rf mast mount preamp; it was not easy and I did use the big guys a lot, but is doable. I don't reccomend it that way, but just saying it can be done. I would suggest at least a 300W amp. A pair of 12 els and the 300W amp will give you a fairly decent signal to work with on 2m. Have done it on 432 with my FT-847 barefoot at 40W to a 25el beam, but the guy on the other end did have a BIG SETUP.
The normal mode for most EME today is jt65 by the way; it can really dig down in the mud.
Earth-Moon (EME) communications -- Wikipedia
Originally Posted by VK3MG
The KEY planning step, for Earth-Moon-Earth (EME) communications is to understand the EME Path Loss (in dB), and what is required at your Earth Station to have a viable operation (hear your own EME echo/bounce).
Loss-eme(dB) = 20Log(F) + 40Log(d) - 17.49
F = MHz, d = km
This translates to as much as 2.25 dB difference in path loss from apogee to perigee.
The mean distance from Earth to Moon is given as 384,400 km.
These calculations consider the fact that the Moon is only 7% efficient as a reflector, use the radar equation (which defines a two-way path-loss model) and the assumption that the Moon is a spherical reflector.
ND2X has a Path Loss calculator on his web site:
Last edited by W9GB; 09-26-2012 at 09:50 PM.
We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths. -- Walt Disney
If you're trying a contact with someone running the antenna at Arecibo you'll have absolutely little difficulty with that. Anybody running a really good setup is your first one to make arrangements with. There are some excellent stations on EME and they are more than willing to help out. You have some of those down in VK land. The use of JT65 is a good choice but you can actually still make contact with the EME stations with CW. It still works well. Some of those aspiring to work EME believe they need to hear their own echo so they can be sure they are getting there and back. That isn't necessary and a setup to hear your own echo is usually just about what you would have as a full blown EME station. If you can copy your return then it's a good bet others can hear it too. Polarization is a problem that can be tackled by having a rotatable array to match the Faraday rotation and the fact that horizontal for you in VK land isn't horizontal in W land. That's in reference to the signal that bounces off the Moon. Think about it, the world is round by the time you get to the other end of the world horizontal in space is now up to 90 or more degrees different. Circular polarization is fine as long as the other station can match it. Linear polarization to circular introduces losses. Not much but you have to remember the signals are going to be just barely there. Add 3db more of loss and it could be a problem.
There's a load of information out there. Search the internet and you'll get some great stuff. The idea of using the ground effect to your advantage has been done by many stations and their antenna arrays are not that massive. If you can get 2 antennas up you have a chance but with a 4 bay you'll do much better. In this mode you don't need an elevation rotator and your window for making contacts is about 2 hours at Moonrise and another 2 hours at Moonset. More power is always desirable and the stations trying to copy you will be happy you are running as much as you can.
Okay, I've done enough damage.
Hope you do well