Internet
controlled 23cm EME beacon by OE5JFL
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To avoid excessive heating of the
SSPA, please do not use the 100W level more than three times in a row.
Give the system a couple of minutes to cool down again.
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To hear this beacon
you must (at least) have a 2m dish with circular polarisation and the
possibility to track the moon. With linear polarisation the minimum dish
size should be 3m.
If you see a yellow
lamp at TX DISABLED, the transmitter
is switched off for some reason.
QRG: 1296.196
Do not forget to
compensate the Doppler shift. The received signal can be off up to
+/-3kHz, depending on moonrise or moonset.
LOC: JN68mg
The
station:
The
system consists of a 5 meter dish (f/D=0.5) filled with 10mm mesh, 100W
SSPA at the RA3AQ feed, G4DDK preamplifier and DB6NT transverter, FT817 and a
webcam.
Access
to dish control and the transmitter is possible via internet by a small
microcontroller webserver.
The
beacon can serve as a signal source with different power levels and you
can measure sun noise with it as well. So you have the possibility to make
comparisons with your own equipment.
The
functions in detail:
Positioning of the dish to: MOON,
SUN and
STANDBY position
Transmitting
a standard text for 1 minute with levels:
100W , 10W
and 1W
Input
of an offset +/- 9.9deg in
azimuth and elevation for optimizing the position
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To
control the system go to the BEACON MAINPAGE
(see the screenshot on the right side)
This
page is refreshed every 5 seconds automatically, it shows you the position
of the moon (or the sun), the position of the antenna and itīs correction
values, and some status lamps.
Sometimes
the auto-refresh does not work very well, if the reloading of the page
sticks, refresh it via your browser.
Click
now at control, and a new page will
open, asking for the login text.
Type
the correct login text here, and click OK
You
can get it from me by email:
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Now
the control page (see on the left side) will open, and you
can activate the beacon step by step:
If
the target is different from MOON (look at the main page), choose
MOON now.
Then
click AUTOTRACK, the red lamp on the main page (AUTOTRACK OFF) should change
to green now (AUTOTRACK ON). You can see the changing dish position at
the main page and watch the antenna movement via the webcam as well: WEBCAM
(The
BUSY/FREE lamps switch from green to red, indicating that you are
controlling the system. )
If
the antenna is closer than 5 deg to the moon in Az and El, not blocked by
the building, temperature and SWR o.k., the TX
will be enabled (green
lamp instead of red
on the main page)
Now
click TRANSMIT with the power level of
your choice.
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A
transmission will last for one minute, starting with text and then 2,5sec
dashes with 2,5sec pauses between for the rest of the time at the 100W level, a
continuous carrier at the 10W and 1W level. During the transmission you see the
transmitted power indicated on the main page instead of the RX noise level.
Choosing
RX(0W) from the menue, will immediately stop the transmission.
After
some minutes of inactivity, the system falls back into the CONTROL FREE and
AUTOTRACK OFF status. If you want to continue, donīt forget to click AUTOTRACK
again. Also be sure that the main page is refreshed.
For
measuring sun noise track the sun, read the noise in dB from the main page, then
turn the dish away from the sun (the 9.9deg offset should be sufficient) and
calculate the drop in noise.
The
antenna is more or less blocked by buildings in some directions. To the east and
to the south 10...20deg elevation are sufficient, but to the southwest 35deg are
necessary. If the dish has no clear sight, the transmitter will remain in the
disabled status.
I
plan to leave the transmitter switched on during weekends and on demand via
email also during the week.
The
whole system is at a school, so there can be a lot of internet traffic during
the week and as a result a slower access to the beacon
Enjoy
playing with the beacon!
OE5JFL
