aarde2moon66

 

Welcome To My EME Page

I first became interested in EME during the late 1980's after I moved to Maui, Hawaii. Being an avid VHF/UHF weak signal enthusiast back in California (my old call was WA6EMV), I was disappointed in the low level of activity in the 50th State. After reading an article about EME (yep, the now famous W5UN "MBA" one), I decided to give it a try with a single yagi and a "brick" amplifier on 2 meters. I was immediately hooked. Since then, my station consists of the following:

  • Kenwood TS-2000 or Elecraft K3s w/ DEMI transverter
  • Home built LDMOS Solid State amplifier - 1000 watts
  • 4 - K1FO's 12 Elements
  • AngleLinear GaasFet
  • Masthead relays (including 50 ohm termination for preamp)
  • Homebrew sequencer and station interface
  • Map65 and TrakBox

What is EME?

EME (which is short for Earth-Moon-Earth) is a method of communications utilizing the Moon as a passive reflector. With the Moon being an average of 250,000 miles from the Earth, this is no small feat. High power (pretty much the legal limit) and high-gain antennas are the norm.

Many newcomers to EME are intimidated by what seems a daunting amount of required hardware. Nothing could be further from the truth! With so many "big-gun" EME stations on 2 meters, even a "modest" station with a single yagi and 100 to 200 watt "brick" type amplifier can give EME a try!

If you're interested in giving EME a try, check out the links below and be sure to check in to the 2 Meter EME Net, held every Saturday on 14.345 Mhz at 1500 UTC..


Hardware for EME

Sequencing

In order to prevent premature death of your favorite GaasFet preamp, as well as making sure all the antenna changeover relays have settled before actually generating RF power (at the power levels used for EME, this is not an option), it is necessary to use a "sequencer", a device that will automatically handle all the timing for you.

When switching from receive to transmit

  • Switch the preamp input changeover relay from the antenna to a 50 ohm terminator to protect its input
  • Switch the coax from the station from the preamp output directly to the antenna.
  • Put amplifier(s) into TX
  • Key radio

When switching from transmit to receive, we simply reverse the above process.

This is accomplished with my Interface below.


Antenna Tracking Interface

I used W9IP's RealTrak for many years but since then, there have been several programs since written for Windows. As I use K1JT's MAP65 program for JT65B, the tracking information for the moon is already written to a file that can be pasred by TrakBox. After looking over the various hardware interfaces for being able to read antenna position accurately, I decided that I could design something for far less money than most of the currently available ones.

This is what I came up with


Radio Modifications

Being a true believer in Murphy, I decided to modify the two radios I use for EME in order to absolutely, positively make certain there was no way I could accidentally transmit into my mast mounted GaasFet preamps. (we all know we do stupid things at times). The modifications I did are simple, require only a handful of commonly available parts and are completely reversible. They also leave no permanent marks on either radio.

Click here for more info


My Antennas (4 x 12 K1FO)

(click for larger picture)

eme2


more EME related pages.