BL-10 is Dead by Richard Dillman

One of the most famous transmitters at the KPH transmitting site in Bolinas, CA carried the designation BL-10. When you serviced this sleek 40kW beauty you walked into it like a room. Its voice was heard across the Pacific on 500kc and 426kc. We knew that BL-10 was out of service. But what of the transmitter itself? Was it still there? Might it speak once again? We had to find out...




BL-10 Is Dead. BL-10. Bolinas Transmitter No. 10. A 40kW streamlined beauty that took up an entire wall in Building No. 1 at the RCA transmitting site, the same building that housed the great rotary gap and the Alexanderson alternators.

BL-10 that held forth on 500kc. from 1959 until a few years ago. BL-10, a transmitter that you walked around inside of like a room when you serviced it (remembering always to touch its delicate parts with the shorting stick first). BL-10 is dead.

We finally got the right key and made our way inside Building No. 1 today. The building itself is in a sorry state with much spalling of the exterior concrete and peeling of interior paint.

Inside, in the first gallery, we saw the covered-over pits that once were bridged by the two Alexanderson alternators that were in service through WWII. We identified what we think must have been the soundproofed spark chamber for rotary gap, the note of which was famous across the Pacific. Overhead the original gantry crane still moved at the tug of its chain, standing by to re-install the alternators should it be called upon for that duty.

It was a struggle to push open the spark chamber door and make our way through several abandoned inner rooms until we emerged finally into the second gallery.

And there it was, lit by light streaming in shafts from the ventilation windows far above. It was a sad sight. The BL-10 of my memory was a giant, humming, elegant transmitter. It had twenty (twenty!) meters in a row all along the top of the cabinets, latching doors that you could open to check whatever needed checking and windows to look through to see the massive, glowing tubes. It sat there and hummed, its relays clicking as it was keyed and changed to the KPH working frequency of 426kc from 500kc.

Now it was sitting quietly in a room alone. Debris on the floor ranged from tangled feed wires and insulators to an unexplained single shoe. Flaking paint chips covered the floor and the transmitter like snow. All the meters were gone. All the tubes were gone. Most of the tuning coils were gone. The plate transformer was gone. The heart had been removed from BL-10 and it was dead.

I took a single picture with the 4 x 5 Speed Graphic (using a flash bulb as Graflex intended, not a strobe), and made my way back through the spark chamber into the blinding, beautiful Pacific coast sunlight. We snapped the padlock back on the door and walked away in silence.


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BL-10 in service, 1992

BL-10 in service, 1992
BL-10 in service, 1992

BL-10 seen in service, 1992

BL-10 as found

BL-10 as found
BL-10 as found

BL-10 as found upon entering Building 1