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Most broadcast transmitters, AM, FM and television, are built with reliability and efficiency considerations. Some broadcast transmitters, if properly operated and cared for, will last fifty years or more. 

Operating an older broadcast transmitter could be more expensive for repairs and replacement parts may not be available. There are fewer technicians around today that are qualified to make repairs on older equipment.

Modern transmitters have plug in “hot swap” replacement modules for simple replacement with little downtime. Newer equipment has problems too. Today almost anyone with some electronics knowledge who can read and follow instructions can make the change out on “hot swap” equipment by referring to the service manual. 

In the past only first-class FCC licensees were allowed to make transmitter repairs and adjustments.  Today’s more modern transmitters, those made within the last 15 years, are somewhat more efficient using mostly solid-state parts, highly efficient power amps and liquid cooling systems with variable speed fans and pumps.

Transistors have replaced tubes in transmitters that required kilowatts just to light the filaments.  That is a lot of current and waste heat to get rid of by air conditioning and water cooling. 

Gates Air gives an extreme example of an inefficient television transmitter running at 560 Mhz with 200 meters of feedline using 24.74 KW power to deliver only 5.52 KW to the antenna.   1   Some of this is feedline loss but typical efficiencies for older AM units is only 30 to 50%.

There are numerous older transmitters in use worldwide that are providing reliable service. Some older transmitters were not very efficient by today’s standards. Efficiency is measured by power out divided by power in.   

One of the NOFARS repeaters has a dependable power supply that is over 30 years old. NOFARS has been blessed with knowledgeable people to keep or repeater systems operational.

As for using an older transmitter, it is important to have a knowledgeable technician who has the know-how, is reliable, and can acquire replacement parts.  Some specialized parts have to be custom made by the original equipment manufacturer. Good technicians that can work on older equipment are in demand and are on call 24/7. Alan Alsobrook has been servicing transmitters in the area for years.

According to Gates Air, the life cycle cost of a transmitter should take into consideration when considering transmitter replacement, including the following items: 

**planning costs

**purchase price, including financing, delivery, installation, licensing

**personnel training

**operation costs

**upgrades and repairs and disposal at the end of life

Increasing electricity costs for the transmitter and cooling costs as well as maintenance and repair must be considered.  Older transmitters may need hard-to-find replacement parts. On older transmitters, labor costs to repair and downtime causing the station to lose revenue must be considered.   Electricity costs are rising and carbon taxes are being added in some countries.   2

New transmitters are very costly.  There are so many factors to consider whether to repair or to replace transmitters.

Thanks to Alan Alsobrook and Billy Williams for their input on this article.

References: Gates Air, Total Cost of Ownership

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