W2ETI Moonbounce Beacon Information

20 February 2006

After over a year off the air, the SETI-League sponsored moonbounce beacon, W2ETI, has returned to the air.  Taking advantage of years of experience running its previous hardware incarnation, many improvements have been made.  Initially, the improvements should be noticeable only as improved "uptime" and a few dB more signal.   A number of additional upgrades are planned as well, which will result in a much stronger signal  - 9dB - and the ability to transmit with a number of modulation formats, including JT65, SSB, and arbitrary I/Q modulation under computer control.

The New Beacon

On top of the rack  (left) is the Yaesu 5600 antenna rotator.  To its right is a 1kW 40dB attenuator used as a "dummy load" when testing the system.

The topmost item in the rack is a power distribution panel for all units that are not connected directly to the UPS.

Immediately below that on the left is an IEEE-488 capable Keithley digital voltmeter, used to independently measure the power supply voltages and other parameters that aren't directly metered over the GBIB.

To its right is an Rohde & Schwarz NAP meter for forward and reflected power.  The sensor head is permanently enclosed in the exciter/amplifier assembly.

Next down, under the separator shelf, is an HP 3488A switch box that selects voltages and signals to be monitored and measured.

Under the switch box is the heart of the beacon, the exciter and amplifier assembly, which also includes the frequency reference and synthesizer.  In the previous beacon, this was a sprawling system; it has been compacted into a 3U unit and neatened up quite a bit.

Hanging in front by some cables is a "Labjack" data acquisition unit, which also has outputs to drive the antenna rotator. 

Under the next separator shelf is one of the 20V, 150A power supplies.  Because the amplifier requires 28VDC, two are connected in series (two shelves down).  This amplifier requires about half the current of the old one, so the supplies are loafing, and, in fact, can easily power a second amp.  And may! 
Under the next shelf is the reference frequency standard.  This actually combines a Rb atomic standard, a GPS-disciplined oscillator, and a quartz oscillator to tell which is correct if the two disagree!
Next separator, another 20V, 150A power supply.
Below the montor/keyboard shelf, left-to right, are two 115VAC UPS units, an HP 5334B frequency counter, and a Dell PC with GPIB card that controls all the hardware. 
At the very bottom is a great reliability enhancer, a 230V 3KW UPS that provides full power for the amplifier.

Updated 05 September 2006