Summer 2007 Issue

The 10-GHz California to Hawaii
Annual Attempt

This July, KH6HME in Hawaii and N6CA in southern California hope to be the first to complete a record-shattering 10-GHz contact via tropospheric ducting. Will they succeed?

By Gordon West, WB6NOA

Chip Angle, N6CA (in the foreground), most likely will be
the first from California
to work Hawaii on 10 GHz. The author is in the background.

July is the magic microwave month for record-breaking tropospheric ducting between California and Hawaii. It was exactly 50 years ago when the late John Chambers, W6NLZ, in southern California completed the record-setting QSO with Tommy, KH6UK, in Hawaii over a path of 2500 miles via “tropo ducting.” The contacts were completed with both CW as well as AM on both 144 MHz and 220 MHz.

During this same time, the military, conducting Operation Tradewinds, established near-daily mainland-to-Hawaii contacts on VHF and UHF, with the largest documented number of completed comms occurring in July.

It was 21 years later when Paul Lieb, KH6HME, a California transplant to the big island of Hawaii, completed the first 432-MHz contact with Louis Anciaux, WB6NMT, in July over the 2500-mile tropo-duct path.

In 1980, Chip Angle, N6CA, completed the first-ever 1296-MHz contact with Paul, running 1 watt via a TRW-52601 transistor driven by a Motorola transistor to a rat-race mixer with a milliwatt at 28 MHz for injection. Chip went QRO with a water-cooled 7289 driver tube that delivered 30 watts output to drive a 7289 amplifier for hundreds of watts out.
The July path between southern California and Hawaii is so predictable that Chip and Paul continued to achieve microwave records, conquering 2.3 GHz, 3.3 GHz, and finally 5.6 GHz, where extraordinary path loss is overcome by Chip’s homebrew equipment at both ends of the circuit—2500 miles, separated by seawater—and hundreds of dB help from the July weather conditions between California and Hawaii.

As this is being written in mid-June, everyone is hoping that this July Paul in Hawaii and Chip in southern California will be the first to complete the record-shattering 10,000-MHz contact.
“The tropospheric duct improves as the frequency is increased until the walls of the duct become too irregular for propagation,” commented J. B. Knorr (“Guide EM waves with atmospheric ducts,” Microwaves and RF, May 1985, p. 67).

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