“The 430 MHz radar transmitter at Arecibo Observatory was built in 1962 by Levinthal Electronic Products, which became Radiation at Stanford, as original equipment for the observatory. The transmitter operates at a fixed center frequency of 430 MHz with a maximum transmitted bandwidth of 1 MHz. Two Litton L-3403 or L-5773 klystrons operate in parallel as a balanced amplifier, with a 90-degree power splitter at the input and a high-power 90-degree combiner at the output, to provide a maximum total peak pulse output power of 2.5 MW. Power is delivered to the antenna platform cia 1,500 Ft. of WR21000 waveguide. Am infinitely variable power splitter on the platform provides transmitter power to feed antennas in both the Gregorian dome (a feed horn) and the carriage house (the line feed). This allows dual beam operation, which could have been called “dual radar” operation, as it is equivalent to two radars pointing in different directions. The maximum duty cycle is 6% so the maximum average output power is 150 kW.”
HAARP Experiments to Get Under Way on February 20 UTC, Reports Invited
On February 20 (UTC), Alaska’s High Frequency Active Auroral Research Program (HAARP) will launch its first scientific research campaign since the facility was taken over by the University of Alaska Fairbanks (UAF) Geophysical Institute 18 months ago. UAF Space Physics Group Assistant Research Professor Chris Fallen, KL3WX, reports that he will be ready to go starting Monday, February 20, at 0330 UTC (Sunday, February 19, in US times zones). His campaign will run through February 23 (transmissions will start 1 hour later on February 22 UTC).
Fallen plans to start and stop each experiment block with an audio broadcast, transmitting AM carriers at 2.8 and 3.3 MHz, with the resulting skywave signal — the “Luxembourg Effect” — being a mix of both frequencies. He told ARRL that he will transmit a short, simple piece of music, composed locally, specifically to help demonstrate the Luxembourg effect.
Transmissions to create radio-induced airglow or “aurora” that potentially can be photographed from nearly anywhere in Alaska will take place afterward; Fallen said on February 18 that he wasn’t quite ready to announce precise frequencies for that experiment.
“Initially the airglow experiments will be a silent carrier, but if things go well the first night I may try a single AM-modulated tone to make the broadcast easier to hear,” Fallen told ARRL. He said net radiated power would be in the 2 MW range.
Fallen is working under a National Science Foundation grant. He’s posting additional information on his “Gakona HAARPoon 2017” blog. He points out that exact times, transmit frequencies, and experiment modes “are subject to change in response to a variety of factors.