Some additional comments on WLW following on to Paul, Barry and Mark's comments.
The RCA installation crew took the WLW rig up to 850 KW out during the initial testing. The actual PA voltage was 12KVDC and the average load on the power supply could go up to 100 amps... 1200KW in for 850KW out. The modulator was running Class B, so high distortion was typical as compared to today's standards. Everything in the rig was basically overdesigned but protection circuits were not always quick to react. With no automatic audio gain control, it was quite common to blow components or pop breakers when the modulation got out of control. The Crosley engineers later developed some of the first audio limiting and AGC equipment to make the rig operate more reliably. There were only six transmitters at the other site, not thirteen. The six 200KW Crosley transmitters down the road were short wave (6 to 24MHz) not medium wave transmitters. They were set up in pairs with two RF decks and 1 modulator and power supply. In that configuration they were transmitting diversity on two frequencies. The calls were WLWO, WLWK and WLWL. Crosley built the station for the Office of War information which later became the VOA. We operate the National VOA Broadcast Museum from the facility along with the Gray History of Wireless collection and the Cincinnati Media Heritage collection. I have a longtime friend who was one of the design engineers for the VOA site and is the last remaining engineer to have run the RCA 500 KW at WLW. We often joke with Clyde as why he never took up ham radio as a hobby. His response is "once you have dipped the plate on a rig at 100 Amps at 12 KV, noting else can excite you". I enjoyed the comments on the 2000KW middle east transmitters. They were built by Harris Broadcast and are solid state. We put similar TX's in the Voice of Vietnam and in the Philippines. My youngest daughter who teaches physics got to visit the transmitters when we had them on the test pad out in Quincy, Il. She was asked to push the big red button that brought the rig from a cold start to 2000KW in about 10 seconds. At 100% modulation (8,000KW PEP) we were melting snow and scorching the grass outside behind the dummy load! Each year on Friday evening during Dayton, Geoff W8GNM, Ted Ryan W8SAI and I host an open house that alternates between the VOA site and the WLW transmitter site. If any of the readers are interested in attending, please contact me before Dayton. We try to limit the size of the expedition to about 40 attendees. 73 Jay K8CJY [email protected] _________________ Topband Reflector
