History of the Press Wireless PW-15 transmitter
restored by the Maritime Radio Historical Society (MRHS)

Built in the 1940s, it was used during WWII by Press Wireless to transmit press reports across the Pacific and around the world. When Press Wireless was absorbed by Globe Wireless, the transmitter was installed at the Globe transmitter site in Palo Alto, CA. After the era of point to point press broadcasts ended, the PW-15 was used as a Morse code transmitter in the marine service for station KFS, talking to ships at sea.

Volunteers from the MRHS recovered the transmitter from the Palo Alto site and installed it (along with another PW-15) at the transmitter site for ex-RCA coast station KPH in Bolinas, CA. It was restored to full operation as the 12.993Mc transmitter for KSM, the station operated by the MRHS. It is believed to be the only PW-15 transmitter still in operation.

In the YouTube video you will see Steve Hawes, Senior MRHS Transmitter Engineer, bring the big transmitter to life. Watch as he confirms the frequency of transmission, turns on the primary power, engages the high voltage power supply and sends a test transmission.

OM Jack Harper, friend to all things Hammarlund, wrote to ask for the coordinates of the KSM/KPH sites so he could look at them via Google Earth. If you haven't yet used this amazing program it can be downloaded from:

http://earth.google.com/

I thought others might be interested in the information, so here it is.

For the transmitter site, use:

37 deg 54 min 52.32 sec N 122 deg 43 min 30.26 sec W

That should put Building 2, built in 1930, in the center of the screen. The half
of Building 2 with the lighter colored roof is Building 2A, built in 1959. This
is where the KSM/KPH transmitters are housed. The road to the lower left leads
to Building 1, the original Marconi transmitter building ("power house"
as it was called), built in 1913. This housed the original rotary gap, later two
200kW Alexanderson alternators, still later many HF, MF and LF transmitters for
marine and point to point work. The antenna field is to the lower right of Building
2 but the antennas are not visible.

For the receive site, use:

38 deg 05 min 44.22 N 122 deg 56 min 51.28 W

This is the point to point receive building built in 1930 to compliment Building
2 at the transmitting site. Note the long, cypress lined driveway leading to the
building. It's quite beautiful. KPH, the marine station, moved to this location
from Marshall after WWII. If you zoom out you will see to the lower left the receive
site for AT&T station KMI. We preserved four AT&T antennas for use at KPH.
To the upper right, past Lunny's quarry, is the receive site for USCG station
NMC, the new kids on the block.

The original 1913 Marconi point to point receive site at Marshall may be seen at:

38 deg 08 min 39.22 N 122 deg 52 min 40.99 sec W

The large red roofed building at the center is the hotel (for staff). The two smaller
buildings to the left are the cottages for the chief engineer and station manager
(similar cottages can be seen at the transmitter site). We reactivated KPH from
Marshall for the first time since 1942 when one of the restored cottages was dedicated
in 2006.


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Richard Dillman, W6AWO
Maritime Radio Historical Society
http://www.radiomarine.org
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