KASN-TV in Little Rock, AR, recently made the decision to replace their PYE TVT analog transmitter in conjunction with the installation of a digital transmitter for KASN-DT. Their decision was based on several factors.
First, obtaining repair parts for the PYE transmitter was becoming increasingly difficult. Second, the transmitter was very energy inefficient. In addition, it was unstable and needed constant attention. As well, the design called for using a common Andrew top-mount antenna for their analog Channel 38 and digital Channel 39. And finally, the N+1 situation with the old transmitter was not attractive.
The facility was dealing with an N+1 situation. The analog station was 5MW ERP, with an antenna input of 92KW, and the digital station was maximized at 1MW, with an input power of 19.1KW.
The engineering staff felt that their existing building was large enough to accommodate both an analog and digital transmitter once the old transmitter was gone for two reasons. First, the existing PYE was actually two transmitters running in tandem, which resulted in a large physical footprint. Second, the newer IOT transmitters were significantly more compact. The transmitter building was also remodeled and a covered concrete pad was added for the heat exchangers.
Some of the difficulties that the engineering staff faced included maintaining an on-air operation with the old transmitter while remodeling the existing building, adding an RF system and the installation of the analog transmitter.
Some of the innovations that were implemented in the new design included the N+1 system, new RF plumbing in the interior, a combined Channel 38 and Channel 39 top-mount antenna, and successful reuse of existing Andrew circular waveguide, which was broadbanded from the original Channel 38 to accommodate both channels 38 and 39.
The architectural considerations included a remodel of the existing concrete block structure, an addition of structural steel to support the interior RF system, the addition of a 20×30 covered area for heat exchangers and beam supplies for both buildings, and re-work of the existing HVAC system and re-routed ductwork.
Ai (formerly Acrodyne) served as the key vendor on the project, and they successfully met the goals that were outlined by the engineering staff and station.
The facility more than met its goals, and the stations are successfully on the air with new analog and N+1 digital. They have radically lowered the cost of their utility bills as compared with the old PYE transmitter. In addition, the on-air quality of analog has been much improved.