CONSIDERATIONS FOR
SUCCESSFUL 6M EME
DXPEDITIONS
By
Lance Collister, W7GJ, Frenchtown, Montana
July, 2005
M2 6M7 Antenna at OX3LX, March 2005. Photo courtesy of OZ1DJJ
I. INTRODUCTION
Until only a few years ago, the prospects of completing a 6m contact
with a rare DXpedition or portable station using the moon were
extremely remote. However, the increased sensitivity of the
recently developed JT65 digital modes by K1JT greatly enhances the viability of
such
"Ultra Long Path" contacts.
It is assumed that JT65A mode will be a key element to
success in any 6m EME DXpedition, and also that interested 6m EME
operators are already familiar with this mode. The standard mode
for communications on 6m EME has become JT65A, which is the most
sensitive of the JT65 modes. Detailed
instructions of how to effectively use the WSJT software for JT65A EME
contacts are available elsewhere and will not covered again here.
New JT65 users are urged to review the following sites:
http://www.bigskyspaces.com/w7gj/JT65checklist.htm
http://pulsar.princeton.edu/~joe/K1JT/Documentation.htm
Our current time near the bottom of the solar cycle is the optimum time
for 6m EME, and the amount of activity on 6m EME has been increasing
dramatically. Remember that an EME station with a larger
antenna essentially "makes up for" a smaller antenna on the
DXpedition end of the circuit. Therefore, the increasing number
of larger home stations (both with and without elevation) greatly
increases the chances for success by a smaller DXpedition station,
provided certain
considerations are addressed well in advance. In fact, the
portable 6m EME station now can probably fill up as much time as is
desired on EME contacts, within the constraints of available moon
time.
6m EME array at W7GJ (4 x M2 6M9KHW fed with 1-5/8" Heliax)
This is by no means to suggest that 6m EME is commonplace or
trivial. In fact, nothing could be farther from the truth!
6m remains one of the most difficult bands on which to operate
moonbounce, and the situation is exacerbated by the fact that 50 MHz
signals are high enough in frequency to be affected by tropospheric
ducting and low enough to be adversely affected by just about any kind of perturbation in the
ionosphere. And, of course, even when conditions are most
favorable for EME, you always run the risk that Faraday rotation will
change the polarity so that one (or both) stations will not be able to
copy the other! This polarization shift is what makes it very
rare for two stations to be copying each other at the same time, and is
the reason why EME schedules are often so long - to permit each station
to have a chance to exchange required contact information with the
other.
M2 6M7JHV yagi installed above the Jersey Amateur Radio Club in May 2005. Photo courtesy of GJ8BCG
Certainly, if you are a DXpeditioner strictly for numbers of contacts with the
simplest equipment, HF is a much more attractive option. However,
if you enjoy the challenge as well as the reward in overcoming the odds
and completing contacts by sending signals 3/4 million kilometers, then
you are just the type of DXer for 6m EME! I have always thought
of EME DXing as having much in common with fly fishing. If
your primary interest was to obtain large numbers of fish, you could
drive to the fish market. However, if you were more interested in
relying on yourself, in a way that will require all your skill and
cunning, then fly fishing will be more thrilling and rewarding - even
if some get away! Like fly fishing, it is the challenge of the
adventure and the process - plus the thrill of actually landing one - that makes it so rewarding!
FT5XO 6m antenna (M2 6M7NAN "Trip Yagi"). Photo courtesy of W7EW, March 2005
There are a number of different approaches that can be used by a
successful 6m DXpedition station, and it is not my intent here to
attempt to prescribe any single protocol which has emerged as being
most
successful. Because this is such a new corner of 6m DXing, we are
all learning from the experience of each DX operation. However,
there are definitely certain subject areas which will need to be
considered prior to embarking on a successful DXpedition, and I hope to
discuss a few of these elements that are particularly relevant to 6m
moonbounce in order to assist stations thinking about preparing for 6m
DXpeditions. I also will suggest some possible operating
options
that have come to light through recent 6m EME DXpeditions, that might
be
used to increase effectiveness during future operations.
II. PLANNING
Certainly, the first thing to consider when you are selecting a
location to set up for a 6m EME DXpedition is to find a good quiet
location. For most of us, the local noise that surrounds us where we
live is something beyond our control. There are many people
who live in urban areas who constantly struggle with high noise levels,
and cannot imagine adding a preamp to make their receivers sensitive
enough to copy weak signals on the 50 MHz band! Certainly, one of the
advantages offered by a chance to set up a portable EME station is the
possibility of finding a place to avoid the high noise that plagues so
many stations on the "Magic Band". Ideally, you will be able to find a spot that
will not require you to aim the antenna toward high power RF
transmitters, industrial areas, noisy street lights, power lines or
other noise sources that will mask weak signals.
If you are planning to limit your EME operation only to the horizon,
you also will want to make every effort to locate the station in as
favorable a location as possible for the best possible ground gain.
Usually, this means finding a clear, flat area, free of "ground
clutter" (hills, boulders or man-made objects such as houses, cars,
etc. that can deflect ground reflected signals away from your
antenna). The best terrain for ground gain is salt water, although
fresh water (such as a large lake or marsh area) or flat open ground
also has been shown to work incredibly well. |

Quiet location with excellent ground gain, as proven by 7P8NK in August 2004. Photo courtesy of VA7DX |
When aimed on the horizon, the vertical pattern of a single yagi
antenna becomes a series of sharp, high gain lobes and deep nulls due
to ground reflections. For most small stations, one of the most
critical elements in the equation for making an EME contact on 6m
involves taking advantage of this extra "ground gain". Indeed, with a good, flat clear area
in front of an antenna (unobstructed by a roof, HF antenna below the 6m beam, etc.), the ground gain of an
antenna leveled on the horizon often makes a well located single yagi
perform like an array of 2 or 4 yagis - at least when the moon happens
to move in front of one of these lobes. The shape and elevation
of these ground gain lobes depends on the gain of the antenna and its
height above ground.
Generally speaking, ground gain lobes are broader with lower gain
antennas and lower height, although the lobes from such antennas also
are higher in elevation and comparatively weaker.
Vertical (H plane) plot of single yagi at W7GJ, courtesy of K0GU

6M7JHV yagi during the J68AS DXpedition June 2005. Photo courtesy of W8QID/J68ID |
For a single yagi antenna at a typical "DXpedition height" (around 20' above ground), there is usually a good second ground
gain lobe up around 15 degrees elevation. The quality of the higher
ground gain lobes will depend more on the condition of the terrain in
the near vicinity of the antenna in the direction toward the moon, and
that is one reason this lobe often seems to be more effective than the
"main ground gain lobe". It is much easier to have some control over
the terrain a few hundred feet in front of the antenna compared to the
landscape many thousands of feet away! Therefore, if you have the
chance to set up by a lake or sea, it is definitely advantageous to be
as close as possible to the water.
Of course, if you have the good fortune to be able to overlook a large
lake or sea so that your most distant horizon is water, you will
certainly also has a negative horizon, just from the curvature of the
earth. In such a case, you will find there is a "bonus ground gain
lobe" located around zero degrees elevation. Be sure to use this extra
ground gain lobe to advantage, and by all means plan to operate when
the moon is down as far as negative 2 degrees!
|
Just as
important as locating your own station to maximize your own ground
gain, it is important to look at the times when other stations will have ground
gain to coincide with yours. This is especially important for
smaller stations and/or stations limited to the horizon (either because
they have no elevation, or because they have only very limited common
moon window with you). The first assumption often is that there
must be very little chance of being able to work another small
horizon-only station. However, upon closer examination, one
often can find a number of potential common moon windows when both
single yagi stations will have ground gain! Remember that you
probably will have first and second lobes on both moonrise and moonset
(perhaps plus an additional "zero degree" lobe due to a negative
horizon), each of which provide an opportunity to match up with one or more similar lobes at the other station.
As you explore possible contacts, remember that the moon
changes in declination every day, so new common moon windows are opened up
with different horizon-only stations each day. As you plan your trip, you
may also want to look at the times of day for your moonrises and
moonsets. For example, if you are going out during a time of year prone to Es, F2 or
TEP, you will want to pick dates affording windows in directions and at
times of day least likely to be interfered with by these ionospheric
propagation modes.
Generally speaking, any disruption of the geomagnetic field/ionosphere
will have an impact on 6m signals. Even if the MUF is not high enough
to produce effective ionospheric propagation at 50 MHz, the chances are quite good
that signals can be deflected off their direct course toward the moon
and back to you on earth. So, ideally, one would avoid periods of
expected cyclical disturbances (such as recurring 28 day coronal
holes). However, the exact timing of these types of solar events
often are not known with the same accuracy months in advance, the same way reliable Es, F2 and TEP seasons can be predicted.
In addition to the above mentioned ionospheric considerations, there
are two additional factors which can play a large role in the success
of a 6m EME operation. Luckily, these are related to the moon's orbit,
and are very predictable. The first is distance to the moon, and
the second is the sky temperature (noise) of space behind the moon.
As you know, the moon orbits the earth once every month, and as it does so, it appears to
move up and down in the sky. The moon therefore appears to pass through
various spots on the celestial sphere, some of which are quiet, and
others that are extremely noisy down at 50 MHz. And of course, you generally also want to avoid days of the month for
"new moon" since the noisy sun will be very close to the moon
then. When the moon
moves in front of a noisy place in the sky, trying to copy a weak EME
signal is just as difficult as trying to hear someone whispering to you
from across the room during a noisy party.
In addition, the moon
moves closer and farther away from Earth over the course of its orbit
each month. This change in distance alone causes a change in
signal strength of about 2 dB. The combination of these two
factors is commonly referred to as signal "degredation".
Degredation is typically expressed as an index in dB, as compared to
the
ideal situation in which the moon would be at perigee (closest to the
earth) at the same time as the sky behind it was quietest. One
would definitely want to plan a 6m EME operation during a time of month
which affords the least amount of this degredation. These
degredation figures (shown in real time on the JT65 operating screen)
are also available in several of the popular moon-tracking computer
programs available for use in planning purposes. One such free
program that is still used by many EME operators is available
here:
http://www.bigskyspaces.com/w7gj/tracker.htm
Unfortunately, the minimum degredation down at 50 MHz may not be
much lower than a couple of dB, because perigee may not happen at the
same time as the moon is
in a quiet part of the sky. These two conditions move slowly in
and out of sync over a period of years. Typically, the 6m
degredation fluctuates between one or two dB and over 10 dB over the
course of a month. If you have been keeping tally, you will
notice that there are many factors that can reduce the already very
marginal signal strengths on 6m EME! Obviously, when signals are
just at the threshold of being detectable under the best of conditions,
even just a dB or two makes a very significant difference! This
may all begin to sound like an impossible game to
win! However, with careful planning, the chances for success can
be greatly enhanced.
III. EQUIPMENT
Perhaps one of the most fundamential elements of a 6m EME station is a
computer with an interface to connect it to the radio, thereby
providing digital capability. An equally important requirment to
operate in JT65A mode is to ensure some way to maintain accurate timing
of the internal computer clock. The reliability of internal
clocks in most computers - especially laptops - are usually quite
poor.
Ideally, one would like to be able to maintain half second accuracy at
least over the course of an hour long schedule. If internet
access is available, there are very popular programs
(such as Dimension
4, Tardis,
DXTIME, or Atomic Clock Sync ) which can be used to automatically reset the computer clock at a selectable interval (such as every 5 minutes).
If there is no internet available, the most common way to keep the
computer clock accurate is to use a GPS unit plugged into
the computer running a program such as
NMEATime. In the
event that neither a GPS unit nor internet is available, the computer
clock can always be set fairly closely by ear using WWV, and fine-tuned
by adjusting the DSEC control on the JT65A screen until the displayed
time closely matches that transmitted by WWV. (Such manual timing
would have to be checked regularly, though!) This last method was
the resourceful technique utilized by operator N9AB to
complete the successful contact from J68AS for W7GJ's 100th country on
6m!
Another important piece of equipment is an amplifier. Outstanding
results have been achieved by stations using the ACOM 1000 amplifier
(kw on HF plus 6m) on 6m EME DXpeditions, but other types of amplifiers
with at least 400w output can also be quite successful. Note that
even a 400w amplifier has 6 dB gain compared to a 100w transceiver. That 6 dB makes a huge difference when signals
are just barely discernable, as they usually are on 6m EME!
Of course, it also is very important to make sure your amplifier can
withstand the roughly 48 second full duty transmit periods of JT65
mode. Usually, the addition of an extra blower or fan to increase the
airflow will permit full power operation for this amount of time. Here
at my station, I use a pair of high volume fans to suck the air out
of the plate compartment on my amplifiers. This reduces the back
pressure on the blower and greatly increases air flow through the
tube. With this simple addition, the exhaust only becomes warm - not
hot - by the end of the full-duty JT65 transmit sequence.
Another very helpful accessory is a preamplifier for the receiver,
although many people have completed 6m EME contacts without an external
preamp. With most commercial transceivers one will definitely notice
the improved noise figure of an external low noise preamplifier -
especially if operating during an optimum time of month (low
degredation factor) from a quiet location. As long as there is low
feedline loss (less than 1 dB), the benefit from such a preamp will be
just as effective if it is installed right in front of the receiver, and
that is they way they are used at most 6m EME home stations.
Very popular preamp among 6m EME stations worldwide is the CA50T
preamp, which features a PHEMT device for high dynamic range as well as
very low noise figure. It is available through the manufacturer,
LNA Technologies:
http://www.lnatechnology.com/lnatech_015.htm
They also have a new RFCA50T model that is RF switched and can be installed directly between the amplifier and a transceiver.
|

Addition of fans to reduce blower back pressure on W7GJ's amplifiers
|
Regardless
of the type of antenna used for a DXpedition, it is very important to
use good quality feedline. The loss in the feedline will be very
critical on both receive and transmit, and one of the advantages
offered by a DXpedition operation often is the ability to set close to
the antenna, so only a very short piece of coaxial feedline is
required. The availability of low loss coax such as LMR600
has been a tremendous asset in optimizing 6m EME stations:
http://www.timesmicrowave.com/content/pdf/lmr/28-31.pdf
Various types of antennas have been used successfully on 6m EME
operations. As already discussed, the performance of a small antenna
can be greatly enhanced through the use of ground gain. Most
successful DXpeditions have used a single, good computer-optimized 6 or 7
element beam. You can view some such antennas on this page, and with more examples here:
http://www.bigskyspaces.com/w7gj/6mEMEstns.htm
There are several good reasons for using the largest possible single
yagi. If the antenna is going to be aimed on the horizon, a single
yagi will generate multiple good ground gain lobes, providing more
opportunities to complete contacts. In addition, the second ground
gain lobe generated by a single yagi is often more effective than the
lower "main" lobe, simply because it is aiming higher, through less
atmosphere/ionosphere, and is less subject to tropo ducting and/or
interference from ionospheric factors.
Another feature in favor of a larger single yagi mounted as high as
possible is that it will be higher and have a lower main lobe angle of
radiation, compared for example, to a pair of smaller yagis stacked
vertically. In some cases where moon windows are very limited, it may
be very desirable to try to maximize the signal as low to the horizon
as possible.
|
7 element yagi at LA8AV/OH0JFB June 2004. Photo courtesy of OH0JFB
|
 |
And, of course, it is mechanically much more secure for a portable
operation to erect and guy a single yagi as opposed to a vertical
stack. If the object is to generate the most gain, a large single yagi
aimed at the horizon is the easiest way to do it!
Mast bracing and antenna rotating is also most easily accomplished with
a single yagi. If the azimuth and readout is manual, a very effective
method I have used on DXpeditions is to bury the mast in the ground
(resting upon a solid object such as a board or concrete block), with a
protractor around the mast. An indicator such as a bent paper clip
taped to the mast is a very accurate and simple indication of direction. |
The following photos of M2 6M7NAN "trip yagi" installations shows how
the mast can be guyed effectively to withstand even high winds.
Notice how the antenna at FT5XO is held at the desired azimuth by the
two lines which are connected to the rear of the antenna. These
lines can be either tied to fixed objects, or heavy moveable objects
such as concrete blocks (which can be easily moved around to change the
aiming of the antenna).
FT5XO 6m antenna (M2 6M7NAN "Trip Yagi"), March 2005. Photo courtesy of W7EW
FP/N6RA 6m antenna (M2 6M7NAN "Trip Yagi"), June 2005. Photo courtesy of N6RA
The
advantages of a single yagi having been said, there also are some very
good reasons to consider a pair of smaller yagis mounted side by
side.
Even though vertically polarized yagis will sacrifice a few dB ground
gain when aimed on the horizon, they can be mounted and elevated quite
simply to track the moon. And because of the mechanical
arrangement, it is easy to aim the array as high as desired - even
directly overhead if necessary!
If a pair of good yagis is used, the free
space gain (when the antenna is aimed up off the horizon) can almost be
as much as the very brief peak in ground gain generated by a
horizon-only antenna. And, as more and larger 6m EME stations come on
the air, portable operations utilizing antennas with elevation will
make the best use of the available moon time. |

6m EME array of two vertically polarized side by side yagis. Photo courtesy of NL7Z
|
| An example of
how a single long boom 7 element yagi with elevation could be used to
expand available moon windows was illustrated by JA1RJU during his very successful May
2005 operation from KH0. Although the elevation was limited to
about
45 degrees elevation, the moon time was substantially increased.
The
elevation was manual, with very simple, easily transportable indicators, as shown in these
photographs (all photos courtesy of JA1RJU). |

7 element long boom yagi at KH0/KH2K |

Elevation mount at KH0/KH2K |

Elevation indicator at KH0/KH2K |
One final note about DXpedition equipment concerns filters. To
ensure that the portable operation does not interfere with local TV or
other communication services, it is advisable to include a good low
pass filter on the transmitter. In addition, if HF amateur transmitters
are being operated nearby at the same time as 6m EME activities are
planned, it will be very important to make sure they also have are
equipped with low pass filters and good grounds. In addition, it
can be very helpful to have a supply of ferrite beads to clip over
audio leads going into and out of the 6m radio and computer, to make
sure that HF RFI does not corrupt the audio lines of the EME
receiver.
IV. OPERATING OPTIONS
There are various strategies that can be employed by an EME
DXpedition
station. Some of the same considerations apply to JT65 mode
operation as also have been used in CW operations. As with CW
operation, it is sometimes helpful to consider split frequency
operation (if QRM is anticipated) and it also helps to have the callers
on JT65A spread out a little bit in frequency. Schedules can be
set up on
one frequency, with random calls always welcomed on another frequency
(or, preferably, a small range of frequencies). As long all the
frequencies are not too far apart (no more than 1 KHz), they can be
viewed simultaneously on
Spectran, and the DX station can determine
whether to continue to call the schedule station or to reply to a
random caller.
Since the familiar CW pileup type of operation does not
work very effectively with JT65 mode (which does not tolerate QRM
well), setting up separate schedules is often preferred. The
biggest problem with this approach is that it ties up large quantities
of valuable moon time (which is especially limited if the DXpedition
has a horizon-only antenna). On the other hand, random CQ's will
very likely create callers, but often not at the same time when the
DXpedition can copy them.
The most productive technique demonstrated so far, is that home
stations who hear a CQ let the DXpedition station know they are being
copied, so they can run a quick schedule. In this way, the DX
station can sequentially run skeds with stations copying him.
This is quite easy if both stations have access to the internet, but
internet is frequently not available from remote locations.
For remote DX stations with which there is no internet contact, it
would seem that the only options are pre-arranged schedules or random
contacts from CQ's. Based on results from this year's 6m
EME DXpeditions, and previous experience with 2m EME DXpeditions, it
generally seems that calling CQ is usually more fruitful in
creating successful contacts - at least as far as the
DXpedition station is concerned. However, because both stations
may not be able to have extended common moon windows to wait for a
suitable situation when a CQ can successfully be answered in real time
two-way contact (if such a situation ever indeed arises), there is still a need to
accommodate some aspect of scheduling with an individual station.
Although basic JT65 contact exchanges and procedures are based on
traditional CW protocols, there are some very attractive new features
possible with JT65 that can be utilized to make random DX operation
more successful. These new methods have been tried to a limited
extent so far, but with good success. Obviously, what would be very helpful would be some
indication from random callers that they are copying the DX station; otherwise, the DX station can
waste much valuable time calling stations that cannot copy him. One way
this currently could be done would be for the caller to send callsigns
plus received dB signal strength level. This could indicate that
reception was taking place, and there would be a good chance for a
quick contact. A possible scenario is the following, shown in
alternating transmit sequences:
DX STATION XMIT SEQUENCE
|
HOME STATION XMIT SEQUENCE |
COMMENTS |
| CQ J68AS FK94 |
|
Calls CQ and sequentially decodes callers using the JT65A FREEZE filter with DECODE button |
|
J68AS K6MYC -27 |
Answers CQ with current signal strength, indicating how well he is copying.
|
| K6MYC J68AS FK94 OOO |
|
Sees that K6MYC copies so replies to him with standard reports |
|
RO |
K6MYC replies with standard shorthand confirmation and reports, which are easily recognizable visually to DX on Spectran |
| K6MYC J68AS RRR |
|
DX acknowledges with final RRR, while still sending both calls so others will know who he is working |
|
73 |
K6MYC lets DX know the contact is complete, with shorthand message also visible to DX on Spectran |
| CQ J68AS FK94 |
|
DX goes back to sending CQ |
There are a few comments are warranted regarding the above random
contact. The first is that K6MYC accepted a couple dB handicap by
sending the signal strength report when he called J68AS to show that he
was copying. However, this may well prove to be an effective
trade-off if the DX station is copying well enough. After all, a
contact only requires 3 minutes, if both stations are fortunate enough
to have mutual propagation, so it is important for the DX station to
identify stations who are copying him at the same time he is copying
them.
The DX station also accepted a couple dB handicap by sending RRR along
with calls. This is very helpful, though, in the event the DX
station had previously replied to another station with a signal report
(such as may be the case if he is interrupting a schedule to make the
random contact). Similarly, the DX station could continue to send
RRR to K6MYC for an extended period of time (even if K6MYC faded away
for awhile), and not worry that the message would be misinterpreted by
any other stations. This ability for the DXpedition station to
answer a random caller (or even call CQ), and then continue to pick up
again in the middle of a contact with a scheduled station, provides
great flexibility for the DXpedition station, and greatly enhances the
chance of successful contacts for all the stations.
In the above example, K6MYC is able to reply using the standard contact
information without callsigns because the DX station will know they are
being sent to him. Furthermore, the DX station will know that
they are being sent from K6MYC because the FREEZE filter already has
been set on him, and his signal (and its exact frequency) can be seen
on
Spectran.
Visually decoding the RO and 73 messages on
Spectran allows the
DX station to focus on decoding other stations and preparing to reply to other callers and/or returning to
his schedule.
The rule that seems to be suggested by this scenario is that (at
least when there are multiple callers detected), the CQing station
working random should probably always send complete calls
along
with OOO, RO and RRR, while the callers can continue to use the
standard
shorthand
messages by themselves. However,
please note that this is possible only if neither station has a
portable callsign. For example, if the DX station had been
FP/N6RA (or the home station had been G8BCG/P), it would not have been
possible in JT65 to send calls at the same time as RO and RRR. An
example of a JT65A screen showing a contact where W1JJ answered a CQ by
W7GJ using such a protocol is shown below:
In the above example, you will note that the RO sequence received
at 1237Z had a "?" after it. A FREEZE filter with a narrow TOL
then was set up centered on the signals's SYNC frequency, and the
sequence was decoded again. The fact that the "?" disappeared
indicated it was a good transmission. The screen shot was
taken as W7GJ was repying with final RRR to W1JJ, using callsigns
in addition to the final RRR (so other callers would know to whom the
RRR were being sent).
The other required element here is that stations calling on
random in JT65A mode ideally would spread out with 200 Hz between
them. This
spacing ensures that they will not interfere with each other, and the
DX station can easily separate them using 50 or even 100 Hz TOL
settings with their FREEZE filter. An arrangement that would
appear to work here is for the sked stations to call 200 Hz DOWN in
frequency, while all random callers reply HIGHER in frequency, trying
to space out at 200 Hz intervals. The DX station could then
clearly identify the sked station (as the only trace with negative DF)
and still be able to see the random callers. To provide an
opportunity to practice selecting and alternately decoding stations
answering a CQ by using the FREEZE filter, six files are provided while W7GJ was completing
first with K7BV (who indicated he was copying, by sending a dB signal
level when he called), and then with K1SG. These can be
downloaded from:
http://bigskyspaces.com/w7gj/JT65Apracticefiles.zip
The problem remains, of course, that with horizon-only capability, the DX
station has little time available to wait for the polarity to rotate in
order to complete a contact where propagation is not mutual. He
probably needs to give it a good 20 minute try before going off to call
CQ or answer other random callers. He can always return to the sked
station later if he sees him again. If the DX station has
elevation, he is not nearly as limited by a few narrow ground gain
lobes, and has the luxury of more time to operate random. In such a
case, it makes sense for the DX station to set up schedules with
horizon-only stations and/or stations with limited common moon windows,
but also to always watch for off frequency random callers, and to call
CQ during any non-sked times.
As experienced JT65 users are well aware, the visual aspect of
receiving EME signals is an equally critical element in efficiently
operating the station. Often, it is
seeing the presence of
calling stations during a receive period that provides the operator the
extra time to decide where to set his FREEZE filter to be ready for the
decode at the end of the receive period, so he can set his next
transmit period accordingly. Obviously, if he simply visually
decodes the final RRR
shorthand message from one station,
he can quickly set up to decode another caller instead, thereby being
able to decode and reply to the new station before the next transmit
period begins. Similarly, if he sees absolutely no visual trace
from the schedule station, but observes another strong station calling
slightly higher in frequency, he safely focus on the random
caller. Or, if he sees a trace on the schedule frequency, he can
set up to first decode that caller, and try to complete with the sked
station. Callsigns and messages are of course quickly selected
automatically by simply double clicking on the caller's callsign.
It is the combined use of the visual waterfall display, along with
skilled selective sequential decoding of various signals that will
enable the DX station to send the most judicious information, and
thereby maximize EME contacts. You will be able to practice recognizing the appearance of the
shorthand messages, as well seeing the different callers, if you download the above practice files.
V. CONCLUSION
In conclusion, I can't over-stress the importance of effective planning
and some actual pre-trip practice with the JT65A software and the
particular equipment assembled for the DXpedition. With good
planning and preparation, you can enjoy the results of
"Ultra Long Path"
contacts - even if the 6m band would otherwise appear "dead".
Whether you are planning a DXpedition for meteor scatter, VHF
contesting, or HF, I hope you will think about adding 6m EME capability
as something special to fill the time when the moon is
beckoning. Here's wishing you a healthy amount of good luck
in making some very special "Celestial Magic" on the 6m band!

On 6m EME, the Magic never ends...