What Does That Tx Really Cost?
Determining total cost of
ownership for a broadcast transmitter involves far more than the purchase
price, energy costs and maintenance.
Geoff Mendenhall, vice president of transmission research
and technology for Harris Corp., will introduce a new analysis tool that he
feels gives a more accurate picture. It factors in considerations such as the
acquisition, maintenance, operating and training costs of all systems in the
transmission facility. He will describe the tool and techniques in his NAB Show
engineering session entitled “Transmission System Total Cost of Ownership.”
TCO is about more than reducing direct transmitter operating
costs, he said. A comprehensive analysis includes the tradeoffs of air and
liquid cooling systems, impact on the overall facility, floor space
requirements, size and the thermal efficiency of the transmitter building. In
addition to the reduction in direct operating costs, another benefit of
improved TCO is a reduction of carbon footprint in support of green technology.
offers this comparison of cumulative TCO of three air-cooled systems vs. a
Most of the attention is directed to DTV transmitters, where
efficiencies of 20 to 40 percent are the norm. FM transmitters — where higher efficiencies
of 65 to 70 percent for analog FM operation and 50 to 60 percent for IBOC
common amplification are typical — can also benefit. State-of-the-art AM
transmitters at the 50 kW level are already operating around 90 percent
efficiency, so there is considerably less room and incentive for improvements.
There are two dimensions to improving transmitter
efficiency. The first is improving the transmitter AC-to-RF efficiency. A major
milestone recently was achieved as manufacturers began to adopt LDMOS
technology, which gave marked improvements over conventional RF transistors and
FETs. Other factors that can improve efficiency include enhanced switching
power supplies, reduction of crest factor and variable speed cooling systems.
The second dimension is how the transmitter is cooled.
Mendenhall notes that for many operators, especially those
starting a new transmission facility from scratch, liquid-cooled transmitters
can significantly reduce the TCO. “Liquid-cooled FM transmitters are virtually
unheard of in American radio transmission facilities,” he said, “although they
are more common in Europe.”On the
other hand, liquid cooling is very familiar to DTV transmission facilities in
the U.S. and abroad.
He notes they have many advantages over air-cooled
transmitters. For a given power level, liquid-cooled transmitters have a
footprint about half the size of their air-cooled brethren. In high-rise
buildings where square footage can be costly, this can reduce the amount of
space needed, and thus rental costs.
example of how the TCO system quantifies cost of ownership, as applied to a
liquid-cooled UHF multimedia TV transmitter. Here, the 20-year cost is about
Since liquid-cooled transmitters come with their own cooling
systems, the costs associated with large air conditioning systems go away. This
includes purchase price, maintenance and energy costs. Mendenhall adds that
most air handling systems have a lifespan of about five years, so regular
replacement costs also need to be budgeted.
He cautions that the decision to purchase a liquid-cooled
transmitter should not be automatic.
usually have a higher initial cost, and if you are replacing an air-cooled
transmitter in an existing facility that already has an air handling system,
the investment in an air-conditioning infrastructure has already been made.
However, if you are building a new transmission facility from scratch, the
advantages of liquid-cooled transmitters may be more profound.”
Mendenhall adds that while liquid-cooled transmitters may be
new to American radio broadcasters, television transmission facilities have
been done this way for years, so the expertise and successful field experience are
available. However, there would be significant costs in developing and
designing liquid-cooled FM transmitters for the U.S. market. He expects rising
energy costs and increased awareness of TCO to drive interest and demand for
liquid-cooled devices. One of the purposes of his session is to test that
Mendenhall’s presentation “Transmission System Total Cost of
Ownership” is on Tuesday afternoon, part of the Broadcast Engineering
Conference session “Green Engineering for Broadcast.”