INTRODUCTION

• Why EME on 6m?
• Independent of high geomagnetic latitude, which makes TE, F2 infrequent and/or impossible
• Declining solar cycle further reduces chances for ionospheric propagation
• Makes up for unfavorable geographic location which does not provide effective Es links to ionospheric propagation, or has poor horizon
• Provides another avenue for working new DXCC countries
• Provides another way for DXCC countries to complete WAS
• 3/4 million kilometer path - the Ultimate DX!
• The technical and operating challenge!

• 6m EME Characteristics
• Rapid Faraday rotation (typically 10-15 minutes)
• Short signal peaks
• VERY weak signals
• Unpredictable Conditions (even when best times of the month are selected for activity)

• New Developments Make 6m EME viable
• New generation of computer-optimized antennas for higher gain
• Commercial HF amplifiers beginning to include the 6m band (Yaesu, Icom, Acom, etc..) so it is easier to run 1 kw on 6m
• WSJT program's JT44 Mode offers more than 15 dB sensitivity compared to CW
• New improved JT65 Mode offers several additional dB advantage, and is even easier to use
• JT65A mode is now the standard for 6m EME, since it is the most sensitive of the JT65 modes
• Usually, JT65 signals weaker than -22 dB are not heard in the speaker at all.  JT65 can process signals 8 to 10 dB weaker  than that level
• No-signal RF level (background noise) shown by JT65 is usually around -33 dB
  
• 6m  now available in most of Europe (but many countries still have restrictive power/ERP limits)
• Japanese hams (very active on 6m and in DXpeditioning) are permitted to operate 6m EME with JT65 beginning in January, 2004

• Examples Shown Here
  
• The JT65A example screens shown here were generated by using .wav files saved during actual contacts
• Because the JT65A screens were not taken at the time of the contact, the actual computer clock times and moon/sun positions shown do not corrspond with the times of the .wav files
• If you would find it helpful to experiment by loading an actual JT65A .wav file (inaudible signal at Sync 2, -23 dB signal strength) of callsigns and reports from W1JJ, you can download it here
  

• Station EME Calculator
• Provides a way to assess your system and determine who you can run a sked with
• Found on the WSJT "ECHO MODE" screen:

• If you can detect your own ECHO MODE echoes louder than "-33 dB" during an optimum time of month, you should be able to complete with W7GJ

• Antennas
• 14 dBd seems to be a good target size for a "real" EME antenna
• This size antenna is capable of contacting other similarly sized stations (provided each has 1000w)
• Additional ground gain (while pointing on the horizon) counts toward the 14 dBd gain figure
• Most 6m stations only have antennas aimed at the horizon (which is fortunate, since small antennas NEED the extra 3-5 dB ground gain)
• Examples of minimum sized (approximately 13-14 dBd) 6m EME antennas include:
• M-Squared 6M7JHV yagi (31' long boom) aimed on the horizon (with ground gain)
• M-Squared 6M11JKV yagi (69' long boom) aimed skyward (without ground gain)
• Examples of next larger class of antennas (approximately 15-15.5 dBd) are:
• One M-Squared 6M7NAN yagi (41' long boom) aimed on the horizon (with ground gain)
• Two M-Squared 6M9KHW yagis (49.5' long booms) aimed skyward (without ground gain)
• Four M-Squared 6M5X yagis (18' long booms) aimed skyward (without ground gain)
• Recommend putting up the largest single yagi possible, as high as possible (unless building a fully steerable 4 yagi array)
• Low loss feedline is very important (and fortunately, the loss at 50 MHz is not very high)

• Low Noise External Preamplifier
• Useful at quiet times of month
• Overcomes high receiver noise figure
• Usually used in the shack (unless transmission line loss exceeds 1 dB)

• Learning JT65
• Program appearance very similar, but much more user friendly than previous JT44
  
• Still some tricks to get the last few dB of sensitivity from the program
• Computer does NOT simply do all the work for you - experienced operator involvement is required
• Essential to practice locally with other stations before trying JT65 on an actual EME sked
• Requires 1 minute sequences (approximately 46 seconds of actual key-down time).

• Amplifier
• Important to run as much power as possible, since there are so many factors that can interfere with 6m EME signals
• May require extra cooling to accomodate the long key-down periods

SCHEDULING

• Choose "Best Time of Month"
• 6m EME is challenging even under most optimum conditions
• Minimize predictable "Degredation"
• Distance to the moon
• Sky temperature behind the moon

• Frequencies mutually agreed to in advance to avoid birdies and QRM (usually above 50.200)

• Avoid "Interfering Factors" (strongest when aimed on the horizon)
• Tropo ducting
• F2 (watch time of day and direction)
• High K index
• High A index

• Ground Gain
• Single beams usually have two (at least) good ground gain lobes
• Elevation and number of ground gain lobes depends on height of antenna above ground
• Two examples for different height antennas

• Upper Ground Gain Lobe(s) often better
• Avoids local obstructions
• Beams through less atmosphere
• Provides additional chances to complete contact

• Multiple Common Window Opportunities (even for horizon-only stations)
• Changing moon declination throughout the month provides common horizon windows with many places on earth
• Moonrise-Moonrise, Moonset-Moonset, Moonset-Moonrise., Moonrise-Moonset options
• Adding Second Ground Gain Lobe further extends the number of common window possibilities

JT65 SETUP

• Computer Required
• Windows Operating system with sound card
  
• Speed of at least 200 MHz recommended
• Computer interface required for PTT and sound card audio lines (typical PSK31 interface is fine)

• Accurate Computer Clock Timing Essential (to within .5 second)
  
• Programs updating time automatically through the Internet (such as Dimension 4)
• GPS units best for remote locations without Internet access

• Receiver
• Flat audio output between 1200 and 1800 Hz
• Widest USB IF filters
• Disable any "tone control" or audio filtering
• AGC OFF (if possible)

• Audio Level
• JT65 screen should register zero dB or very close
  
• Adjust level with RCVR volume control and/or Windows computer sound card recording level control

• Specify Station to be Called
• Enter callsign in "TO RADIO" window on left side of the JT65 window
• You also must enter the other stations 6 character grid locator in the window to the right of the "TO RADIO" window
  
• If callsign is included in the file "CALLSIGN.TXT", you can also press the "LOOKUP" button to automatically enter station's grid locator
• If the station is not listed in your "CALLSIGN.TXT" file, you can press "ADD" to include the call and locator for future reference.
  

• Select Proper Transmitting Sequence and Mode
  
• Shown on the right hand side of the JT65 window
• Agreed upon in advance

• Select Standard Message Text Generation

• Automatically formats messages with grid locator included, for maximum encoding sensitivity
  

• SYNC Levels - Indicate reliability of the decoding
• Act as a "Threshold" level for accumulating callsigns into the lower Average Message window
• Usually set to Sync 1 for weak signals, but you must watch DT and DF carefully for "false" decodes when SYNC is less than 2
  

• AUTO ON/OFF
  
• Button must be pressed to ON in order to begin transmitting and receiving actual signals
  

• Typical Example of Proper Setup

• JT65 screen shows proper audio levels (as indicated by the display in the lower center of the screen as well as the green audio input (lined up with the small "tick marks" on both sides of the JT65 signal window)
• Station to be called (W1JJ in this case) is entered in the "To Radio" box, along with the 6 digit grid locator
  
• "Gen Std Msgs" button has been pushed to create the proper messages shown
• Note also the typical "DT" for the message received, showing it was indeed a signal delayed by the path distance to the moon and back (should show approximately 3 second delay  if both computer clocks are properly set)

ACTUAL JT65 OPERATION

• Do not change receiver frequency (during receive sequence)
• Do not change transmitter frequency after beginning to transmit (the other station may already have a narrow FREEZE filter on your signal)
• Weak Birdies/Multiple Stations Can be Viewed (carrier birdies or JT65 sync tone) on slow waterfall displays
• Big Spectrum (WSJT version 3.8.1 and later) provides summary of what has been processed during receiver period
• SPECTRAN program provides sensitive spectral display, but requires second computer for real time monitoring:

• Other Station's Moon Position
• Moon position of the "TO RADIO" station can be displayed instead of the position of the sun
• Click on the sun position display with the mouse to display moon position instead
• Clicking again restores the sun position information
  

• Simple Callsign Messages
• Usually stronger than -25 dB for reliable individual decode
• Shown sequentially in the upper JT65 window
• Callsigns accumulate to the AVERAGE shown in the lower window if there is a "*" shown after the message
• Message #1 must be selected by clicking in the circle to the right of the message prior to beginning your XMIT period

• Callsign and Reports Messages
• Same senstivity as simple callsigns alone, due to the fact that the messages are encoded differently to indicate reports are also being sent
  
• Shown sequentially in the upper JT65 window
• Callsigns accumulate to the AVERAGE shown in the lower window if there is a "#" shown after the message
• The reports of "OOO" will only be shown in the upper (individual messages) window, so be sure to watch there for reception of the reports
• Message #2 must be selected by clicking in the circle to the right of the message prior to beginning your XMIT period

• "Shorthand" Messages
• Shown only in the upper JT65 window, and do not accrue to the AVERAGE, so be sure to watch there for reception of these
  
• "RO", "RR" and "73" are "shorthand" messages and are not decoded in the normal way
• Utilize the sync tone plus one other tone at different tone spacings to indicate these messages

• RO             53.8 Hz      107.7 Hz    215.3 Hz
  
• RRR           80.8 Hz      161.5 Hz    323.0 Hz
  
• 73             107.7 Hz      215.3 Hz    430.7 Hz 
  

• Can be accurately decoded by JT65 even if signals are as weak as -30 dB
• Do not depend on your SYNC setting
  
• Appropriate message can be selected by clicking in the circle to the right of the message prior to beginning your XMIT period
  
• Any of these messages can be selected DURING your XMIT period.  This permits changing your message immediately upon noticing decoding of the appropriate incoming message from the other station.  To change the message DURING your XMIT period, you must press the "TX#"  button to the right of the indicator circle.
  
• Because of the distinctive frequency splits, can be easily  decoded visually by watching with a program such as Spectran

Spectran display of RR being received from W1JJ on JT65A mode.

• Message Average
• Single line shown in the lower section of the main JT65 window
• Averages all callsign messages that exceed the SYNC threshold set by the user
• Can accumulate an average of much weaker messages
• Usually, nothing appears here until program has accumulated what it believes is the correct message
  
• Remember to press "CLEAR AVG" when you begin receiving a new (different) message, or the average line will just become increasingly garbled
• Only non-"shorthand" messages are included in the average window, so you can continue to accumulate callsigns in the average window, even if the other station is sending calls plus OOO reports.

• CLIP function
• Reduces effects from static crashes but sacrifices some sensitivity
• Normally set at zero

• ZAP function
• Reduces effects from birdies but can sometimes cause a small loss in sensitivity
• Normally set at zero

• FREEZE filter
• Used to filter out birdies and/or separate multiple stations
• Filter width adjusted by changing the TOL setting
• Increases JT65 sensitivity slightly
• Must first make sure you know the frequency of the other station.  If signal is strong enough, a spike will be shown at the frequency of the SYNC signal, shown on the RED JT65 line
• Set FREEZE filter by moving mouse to peak on RED line (until the units values under the graph turn red), click on the spike, and then check the FREEZE box. (above the date and time display near the bottom of the JT65 screen).

• Necessary to invoke the FREEZE filter (with TOL less than 100) to eliminate a "?", and properly decode shorthand messages

Receipt of RO from W1JJ without FREEZE filter activated.  Note the "?" after the message.
.

• Watch DT and DF (values shown just to the left of each received message) to decide if  you should INCLUDE or EXCLUDE an individual message from the lower Average Message window
• The lower you set the SYNC threshold, the closer you must watch DT and DF values to make sure you are decoding a "real" message
• DT should indicate an appropriate delay by the trip to the moon and back (typically around 3 seconds)
• DT values displayed for shorthand messages do not reflect the actual time delay to the moon and back
  
• DF should show consistent frequency difference (unless you have changed your receiver tuning)

• The W parameter should be within a few Hz for successful synchronization
• Of course, a good clean outgoing signal SHOULD have a narrow tone width
• Width of the signal can vary depending on multipath or ionospheric aberrations

REFERENCES

• W7GJ's Pages
• JT44 Tips and News
• Welcome to 6m EME
  
• 6m EME Tips
• 2m EME Tips
• TRACKER, CALLSIGN.TXT, SPACE (for calculating clearance of any size fully steerable array) programs Download Page
• K1JT's WSJT Home Page
• N0UK's JT65 and  JT44 Schedule/Chat Page
  
• Hamtronics (source of LNY-50 preamplifier)
• LNA Technology (source of high performance CA50T receive preamplifier)
  

CONCLUSION

• Examples of some of the successful W7GJ contacts with single yagi DXpedition stations include:
  
• CY9DH
• ES8X
• 3V8SS
• IS0/I0JU
• OX3LX
• KH0/KH2K
• GJ8BCG/P
• J68AS
• ST2RS
• YA1RS
• 4X/ZL1RS
• FP/N6RA