A New Ham’s View of EME

As a new ham, I am in the process of discovering where my interests in
amateur radio lie. Since I have only been licensed for about 18 months, many
different ways of operating are new to me and usually pique my interest to
learn more. Several months back a presentation given at an OVH meeting about
EME introduced to me to this new and quite exotic mode of operating. When I
saw was required in terms of antennas (W5UN’s antenna array, among other
things) and other operating equipment I was shocked. Due to the location of
my QTH, my home ham shack is somewhat limited (due to antenna restrictions)
and operating on some modes where large external antenna arrays were required
was going to be out of the question. So I temporarily put EME on the back
burner until a couple of months ago when I got into a conversation with a
couple of hams on 448.325 repeater on the way home. They introduced
themselves to me as Terry (K8ISK) and Chuck (W4XP) and told me they were part
of a VHF/UHF contest group formally called "The Delmarva VHF and Microwave
Society" but nicknamed the "Grid Pirates". The Grid Pirates Contest Group is
the result of Ken Ramirez's, N4UK, search for a way to activate rare
Maidenhead Grid Squares during various V/U/SHF and Microwave band contests.
Moonbounce is another one of the modes that the Grid Pirates like to operate
on especially during the ARRL International EME contest. After talking with
Terry and Chuck on that fateful day, I received an invitation to join them
during the ARRL EME contest to get an up close and personal view of this
rather exotic mode. A brief description of what EME is follows.
 

Moon bounce has been described as the ultimate long path DX. It allows you to
literally work the world on the VHF and UHF bands. Not too long ago, EME
might have been beyond the reach of many hams. However, this is no longer the
case. There are thousands of active stations working EME on all bands from 50
MHz to 10 GHz. EME signals are considered the weak signal of the weak signal
work. As a result of this, almost all contacts are made with CW (being a CW
operator that really interested me).Some of the larger EME stations will
sometimes use sideband but this is the exception, not the rule. Also EME
signals exhibit a phenomenon known as the Doppler shift since the moon moves
in relation to the earth. At moonrise, a 2 meter EME signal may shift in
frequency by as much as 350 Hz. The Doppler comes slowly down, reaching zero
when the moon is passing your longitude (due south or due north azimuth
heading) then starts to shift in a negative direction going down in frequency
by as much as 350 Hz by moonset. Always tune with the RIT when looking for an
EME station to contact due to the Doppler effect. Because signals are almost
always weak and not always out of the noise, almost all contacts are made
with accurately timed transmit and receive sequencing (unlike other modes of
contacting other stations). Also some of the other conditions necessary to
help in successful moonbouncing including the tradeoffs involved with the
sky/sun temperature and earth/moon distance. To operate successfully on
moonbounce a lower sky/sun temperature and a close moon/earth distance are
desirable. EME can not be operated during a new moon and there is no
difference in signal strength during the other phases of the moon . I would
have thought that during a full moon the signal would be the strongest but
that is not the case.
 

So with this as a brief background let me tell you about my trip up to
Terry’s QTH up on Bull Run Mountain to witness this mode. Since Terry’s house
was up on Bull Run Mountain (elevation 1000 ft) and my car is not exactly a
mountain vehicle I contacted a good friend of mine, Bob Raevis KT4KS, and
asked him if he was interested in going up on Bull Run Mountain to witness
EME in action. He readily agreed to travel up the mountain with me. Since
both of us operate on CW almost exclusively seeing another way to send CW was
a very interesting prospect. So on the evening of October 30th Bob and I
headed up to Bull Run Mountain. Terry immediately showed us the standard 22
element KF 10 Yagi array (complete with azimuth and rotating rotors) attached
to one of the two refurbished school buses that the group houses all of their
equipment.. We were going to be witnessing 430 MHz moonbounce so we got a
look at the equipment used for this: Kenwood TS850S transceiver, a computer
complete with contesting software programmed with the call signs of all known
EME stations as well as a computer program that calculates the position of
the moon to permit the antenna array to be adjusted. Just as the moon was
rising over the mountain, RIT adjustments had to be made to allow for the
Doppler shift. After the RIT is set, it is tested by listening for the 2
second delay echo (because the round trip distance for a radio signal bounced
off the moon is about half a million miles, it takes slightly over two
seconds for the signal to complete its trip). It was very neat to hear your
own CW signal come echoing back at you.
 

While we were there, Terry made about a half dozen contacts to stations not
only in the US but also to DX locations like Germany, Finland and South
Africa. The CW signals are indeed extremely weak and it takes intense
concentration to copy all of the information needed for a legal contact.
Because of the weakness of the signals, all of the information is sent
multiple times (at least 10 times) so the station at the other end can copy.
Bob and I both had trouble copying some of the incredibly weak signals since
both of us are used to the signals generated on 40 meter CW. After this
experience I promise not to ever complain about the QRM on 40 meters again!!
 

After staying for a couple of hours we headed home. I truly enjoyed getting a
chance to see what moonbounce was all about. Many thanks again go out to
Terry Price (K8ISK) for allowing a couple of strangers come up and observe
his operating position. I would recommend a visit to the Grid Pirates web
site (www.qsl.net/dvms_k8gp) to get a closer look at all of their operating
equipment and the history of their group (you can even schedule a contact
with the group on their web page as well). Finally a big thank you to my
partner in crime Bob (KT4KS) who did a superb job as both chauffeur and
secretary (not to mention friend and companion). I would recommend that if
any of you get the chance to see an EME station take the time to see what it
is all about. After that I promise that you won’t think of the moon in the
same way again.
 

Ruth KU4WH