Since the mid 1970's Peoria's News and Talk Station 1470 WMBD has been served up by a Continental Electronics 315R "Power Rock" transmitter.  One of the finest and best sounding transmitters ever made, the 315R was one of the first to employ PDM modulation using 2 tubes and a 13,000 volt power supply.  The backup transmitter until the late 1990's was Gates BC5H.  In late 2000 an additional 315R was purchased and the BC5H was delegated as an "off the grid" backup.

 

Due to a projected lack of parts from Continental and the age of the main and the 2 backup transmitters, the decision was made in the Spring of 2010 to replace the main 315 R with a new Broadcast Electronics AM6A transmitter.

 

The first part of the project was to remove the massive Gates BC5H from the location it had held since the early 60's.  The weight was lessened by removing the power transformer, modulation reactor and capacitors (still stored on site).  With the help of Jim Moyer (of Moyer Electronics in Groveland) and several steel pipes, the Gates was rolled out of the way and into a position where it will become a storage cabinet after the interior is completely gutted and cleaned.

 

The Gates BC5H out of the way and the location for the new transmitter.

On Monday, May 3, 2010 Allied Van Lines showed at the Groveland site and unloaded the new Broadcast Electronics AM6A Transmitter.

A quick skid loader trip across the driveway and it was in the building.

Just like unwrapping presents at Christmas.

With the modules in place, the antenna, power, remote control and audio wiring began.

All wiring was completed on Wednesday May 5th and we waited patiently for a St Louis Cardinal game to end before we switched the antenna lines.

Shortly after 10pm, we took WMBD down for about 30 seconds while the lines to the phasor were switched to the new transmitter.  After about an hour of testing on the dummy load and audio adjusting, the AM6A was switched to the antenna system.

The 315R purchased for backup purposes in 2000 will remain in that roll.  The main 315R will be maintained as an "off the grid" and "off the antenna" standby that can be switched on in case of a catastrophic failure. 

Thanks to Mike Sabol for his help with the install, pictures and willingness to stick his hand the "mouse racetrack" (aka wiring trench) beneath the floor to trace down wiring. 

On a sad note, WMBD ceased AM Stereo operation when the main Continental transmitter was switched off.  As good as it sounds, AM Stereo radios are no longer being manufactured and maintaining the technology is no longer viable especially for a news and talk station.  That leaves WMBD's sister station WIRL and Chicago's WLS (nighttime when the IBOC is switched off) as the only 2 known AM Stereo stations operating in Illinois.

 

One final thing. We have affectionately nicknamed the new WMBD transmitter "Milton."  If you've been around long enough, you know why.