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Maritime Radio Historical Society’s Museum Station K6KPH is Back

05/15/2018

Maritime Radio Historical Society (MRHS) Amateur Radio station K6KPH in is back on the air after a brief hiatus, although still at a minimal level at this point. K6KPH, intended as a tribute to KPH, the “wireless giant of the Pacific,” relays the W1AW Field Day Bulletin, and W1AW Morse code practice qualifying runs for West Coast amateurs.

“Not all the K6KPH frequencies were back on at first, as we had to change antenna assignments to get the minimum service we have now,” said Steve Hawes, WB6UZX, who explains that K6KPH is “sort of” back as some repair work is pending.

Hawes said the crew of K6KPH volunteers made some temporary repairs to get some antennas back in service, and the station now is usable on 80, 40, 20, 17, and 15 meters. He said K6KPH expects to be ready to handle the qualifying run transmissions starting with June’s, and also will be transmitting the Field Day bulletins.

“For the FD digital transmissions, I’ll have to wrestle 7/8-inch Heliax between two different transmitters on 7 and 14 MHz,” Hawes noted.

K6KPH uses the original KPH transmitters, receivers, and antennas; no amateur equipment is employed. The transmitters for most bands are Henry HF-5000 commercial units, but the 1950s-vintage RCA commercial units, known as “K” and “L” sets, are used on special occasions. Transmitting antennas are double extended Zepps for frequencies below 12 MHz (K6KPH and KPH prefer megacycles to megahertz), and H over 2 for 12 MHz and above, all fed with open-wire line.

History

The Bolinas, California, site that’s now home to K6KPH and KPH originally was a 1914 Marconi Company facility with a 350-kW low-frequency rotary-gap transmitter for overseas radiotelegraph traffic. After World War I ended, RCA took over the site and installed 200-kW Alexanderson VLF alternators for commercial traffic, and the KPH maritime transmitter. HF and new buildings were added in the late 1920s.

Point-to-point HF service was discontinued in the late 1960s and early 1970s, when satellites took over the traffic. Marine service continued on LF, MF, and HF for a while longer. RCA modified the HF point-to-point transmitters for CW and NBDP (marine telex) in the late 1970s.

“The station was sold a couple of times, and MCI International was the last operator, selling the license and closing the station in 1997,” Hawes recounted. “MCI replaced all the transmitters with new Henry 5 kW commercial units and rebuilt the antennas. Globe Wireless purchased the KPH licenses and operated the KFS Half Moon Bay/Palo Alto facility, and the KPH frequencies from other sites.”

Hawes said the Bolinas/Point Reyes sites were dark until the Maritime Radio Historical Society made a proposal in 2000 to the National Park Service — Point Reyes National Seashore to restore and “interpret” the site, which would include putting it on the air.

“The NPS does maintain the building and pay for the power, but there isn’t a regular budget for radio and antenna maintenance,” Hawes explained. “MRHS has been buying tubes and parts and paying for some antenna repairs and tree trimming. The Park has obtained grants over the years for major antenna work, and there is another one pending for later this year to rebuild some of the ‘H-Frames’ — transmission line supports. The work we did — and paid for — was to get back on the air until the full rebuild work is done.”

Hawes said 20 HF antennas are on the site. The 4, 6, and 8 MHz antennas are extended double Zepps (0.64 l for each dipole element). The 12, 17, and 22 MHz antennas are referred to by RCA as “H-over-2” types — a mini-curtain with eight half-wavelength phased elements in two rows. A Marconi T antenna is on site for the 500 kHz KPH transmitter, and there’s an 800-foot flat top and a 100-foot vertical wire at the center of the flat top.

 



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