During 1968-1969 I was stationed in San Diego at Naval Communications Station SD (NPL). My duty station was the Comm Center in downtown San Diego, however there were multiple pieces to this station as was the norm for Communications Stations world wide. Other parts included the receiver site at Imperial Beach, about 17 miles south of downtown and located on the “Strand” just north of Tijuana Mexico. The transmitter site was located east of downtown about 15 miles or more and located at a place called Chollas Heights. The transmitter site was dominated by 3 600 foot towers which held up a triatic antenna. Essentially this was a vertical which ran up the center of the three towers and then a top hat was suspended between the three towers. I never knew how and when these jumbos were erected but this weekend I came across a newspaper clipping posted on the web from a San Diego paper circa 1917. It has a picture of Chollas Heights as it would have appeared before 1920. You can see how dominant the towers were to the surroundings. When I was here the array was driven by a high powered VLF transmitter which would output on the order of 100 K watts. I seem to recall it having two cabinets each capable of 100 K or so and could be combined. I didn’t work at the transmitter site and my memory is failing so specifics should be taken with a grain of salt.
If I can find a decent picture of the receiver site antenna I will include it in a future post. It was called a Wullenweber antenna and looked like a multiple circles of telephone poles of varying heights arranged in concentric rings. It was used for receive but also direction finding as it was driven by goniometers. Three or more such receiving stations could be slaved together to obtain some pretty awesome fixes.
Thanks for reading my Blog. Best, Chas W5PG