The frequencies of WLLH's two transmitters appear to be unlocked

[DanStrassberg]

For the last maybe three or four years WLLH's two transmitters have apparently been almost perfectly locked together in frequency. I have not been able to detect any beat note between them. Before WLLH Chief Engineer Chris Hall installed a GPS-based frequency-control system, the two transmitters typically ran a few Hz apart, which caused a sub-audio beat note that was easily detectable as repetitive increases/decreases in signal strength here (Arlington Heights, just north of Route 2 and just east of the Lexington line). Well, yesterday afternoon (11/26/2011), it appeared that the transmitters were not locked because the beat note (in the neighborhood of 1 Hz) was noticeable. I assume a component of the GPS-based system has failed or has been removed (possibly by thieves) and needs to be repaired or replaced.

 

[chrish]

Dan, before the GPS WLLH had an Iridium standard oscillator on each RCA BTA 1R transmitter which was pretty bad if you listened to WLLH durning the
60's through 1990 or so. Horrific fading along 495 and to the south and north of the two sites you would hear a rolling fade. The GPS installed on the new Harris
SX-1's cured the probem 99.5% everywhere, along 495, River Road or 110 you would hear just a blip or two in the middle.
Both SX's are gone, I put new Harris DAX-1 in about 3 years ago.
When one of the GPS units failed years back one of the SX-1'S was run on its internal oscillator with the beat being so severe that the Lawrence transmitter had to be shut down until the GPS power supply was repaired. Company that made the units are still in business but they stopped making and supporting the units
many years ago. I stopped doing WLLH after the new owners Goris Group took over.