rf everywhere

The original transmitters at that site were made by Crosley. Green metalflake paint and big glass doors in front of the finals. Beautiful examples of '30s industrial design, but built before Television. They tried numerous methods to eliminate the TVI, and were replacing them with custom designed National radio transmitters. When you changed frequency, the transmitter reduced power and self tuned every stage. All 10, or any combination could be fed from one MFO for power levels from 50 to 500 KW. The self tuning was done with detectors to measure the signal and large servos to drive the variable capacitors & roller inductors.

The new control room had two layers of corrugated concrete precast panels stacked at an angle to allow them to run cabling between any two racks or consoles by drilling holes in the panel(s). It was being converted to the secondary control point for the VOA network, and a private microwave link to Washington D.C. was under construction to the earth terminal to uplink the various feeds. If that failed, other VOA stations were to tune in to the Bethany plant and retransmit. That curtain antenna was a sight not to be missed. Three huge towers, with the network of antennas strung between them. We had to get special permission to tour the site, and had armed MPs follow us through the building & grounds.

Once upon a time i had a USC-30, 2 to 30 MHz 1kW transceiver, in my care. It auto-tuned in the same way. I got to watch it once (with the covers off) and it was a thing of beauty to behold. It had its own low power (50 W) dummy load and tuned up into that. Then it commanded the auto-tuner of the selected antenna to tune up. Just beautiful, but 30 seconds for any frequency change from 100 Hz to 28 Mhz. You used a different receiver and antenna to find an empty spot in an authorized band to transmit.

?-)

You could see all of the hand crank tuning knobs on the front of the transmitter turning at the same time. :)