Published:  TV Technology

Issue:  8/7/97



Choosing a DTV Transmitter

by Joe Fedele





MIAMI--As broadcasters begin to focus on upgrading their transmission facilities to DTV, many 

are looking through catalogs and shopping around.  And, as in any industry, some manufacturers 

are more well known than others.

        

But popularity and name recognition is not always indicative of the best quality, reliability, or 

value for the dollar.  In fact, there are times that smaller companies can actually provide better 

and more personalized services than the larger ones.

        

The constant delays by the FCC in finalizing a DTV standard has forced some of these smaller 

companies to hold back on completing their DTV product lines.  Consequently, not all radio 

frequency (RF) equipment manufacturers have DTV products "in-hand."

        

However, this should not discourage broadcasters from seeking out these companies and 

reviewing their existing NTSC line, as they are generally a good barometer for future product 

introductions.

       

 When asked about what role smaller companies play in the DTV marketplace, Dennis Pieri, 

chief executive officer of Bext, replied that "small companies take up a different role in 

broadcasting but both are necessary and useful," he said. "Big companies have an edge in pure 

research and can invest larger sums of money in trying new technologies.Ó  

        

This, he continued, is good because not all small companies have the resources to fund 

complete R&D efforts. "Even though we may be five months behind, we're working hard to be 

able to offer quality products for the DTV market.  We [smaller companies] could offer 

broadcasters a Toyota instead of a Lexus.  Unfortunately, though, the biggest roadblock we face 

is exposure and name recognition."

        

TV Technology decided to take a look at a few RF equipment manufacturers that may not be 

household names, but whose analog transmission products were on display at this year's NAB 

and should be seriously considered by anyone researching transmitter and microwave products.  

        

Bext, Inc. is a San Diego, California company that specializes in the marketing and servicing of 

high-quality transmitters for radio and television broadcast.  Its transmitters and power amplifiers 

are used throughout the world by commercial and educational radio and television stations for 

local, regional and international broadcasting.

        

Although its primary product line originally consisted of mostly radio transmission equipment, 

Bext expanded into UHF and VHF television transmitters several years ago.  Currently, the 

company offers single-ended transmitters ranging from 2,000 to 60,000 watts. Their Dual 

transmitter systems can deliver up to 120Kw of power. 

        

Their highest powered UHF transmitter is a 60Kw single tube Diacrode with a steam-condensed 

cooling system.  Their maximum power level VHF transmitter consists of a 30 Kw air-cooled 

system utilizing a single TH371 power tube for the visual cavity.

        

Bext plans to have a DTV transmitter available by the end of 1997 and have "product in-hand" 

for the 1998 NAB convention. 

        

Itelco is an Orvieto, Italy company that has branch offices in Westminster, Colo. and Miami. 

They've been making transmission equipment since 1975 and have installed more than 5,000 

systems in over 60 different countries around the globe.  Its UHF line consists of a wide variety 

of transmitter tubes that include IOTs, Tetrodes and solid state models ranging up to 60Kw of 

power for a single ended system.   The company's high-band VHF transmitters can provide up to 

40Kw of power.

        

Itelco's newest TV transmitters employ an innovative "high technology, liquid-cooled thermal 

transfer plate (cold plate) cooling system." Itelco claims that the closed loop re-circulating liquid 

system provides almost a thousand times greater heat transfer per fin area than forced air 

cooling and is "nearly maintenance free." There are no expensive filters to be cleaned or 

replaced and only a maintenance check every six months is required, according to the company. 

        

With regard to its DTV products, Bruno Manzo, sales manager for Itelco-USA notes that, "the 

company already has an 8-VSB modulator and a transmitter wide enough to cover the DTV 

band. Itelco will be a big player in the DTV marketplace."

        

Advanced Broadcast Systems (ABS), in Burlington Ky., has established itself as a provider of 

high-power transmitters to independent broadcasters with its CST-2; avialable in both 20 Kw to 

280 Kw analog NTSC/PAL or 30 Kw to 220 Kw (peak) digital versions. At this year's NAB, the 

company announced its intention to broaden its product line with its Best series of UHF 

transmitters, also avialble in analog or digital configurations.

        

These medium-power transmitters encompass power levels of from 10 Kw to 44 Kw for 

NTSC/PAL to 5.0 Kw (average) to 25 Kw for DTV. The digital line includes a crowbarless 

switchmode power supply (ML-2000) and either the Zenith/Emcee or the ITS 8-VSB exciter.

       

 In June the company conducted a series of high-powered digital tests on both IOT tubes and 

klystrons in conjunction with ITS Corp. at WBNX-TV, in Akron, Ohio.

        

All ABS transmitters are upgradeable to DTV, with a few modifications. "We've always given 

careful consideration to the upward compatibility of our systems to the emerging DTV standard," 

said Daniel Adams, marketing director for Advanced Broadcast Systems. "That's why our 

existing NTSC equipment is totally compatible. During our digital testing, we actually passed a 

digital signal through our analog equipment and it worked very well. Our message both at NAB 

and today is that we are actively promoting digital in our product line."

        

For stations interested in entering the DTV market at a reduced power level, there are several 

other manufacturers that have traditionally concentrated on the LPTV and MMDS markets which 

also bare consideration.  Some have already announced their plans to enter the DTV market. 

        

ITS Corp. has long been a leading manufacturer of wireless broadband transmission products 

and multichannel video distribution applications.  Their product line includes microwave MMDS 

transmission systems, low- and medium-power UHF/VHF transmitters topping out at 5 Kw of 

power and custom configured UHF/VHF exciter systems.

        

ITS introduced its new ITS-8800 series of solid state digital UHF transmitters at NAB this year.  

The 8800 series is a solid state system built on "advanced digital technology."

        

According to Dale Dalesio,  broadcast product manager for ITS, "the transition to DTV for a 

broadcast station will be a significant undertaking. ITS is prepared to offer the DTV products and 

application solutions that broadcast engineers and general managers will require. With the 

introduction of the ITS-8800 DTV solid state UHF transmitter series, we are committed to 

providing the highest level of system integration, customer service, and product performance."

        

Veltek Industries, based in Tampa, Fla., provides transmission systems for UHF, VHF, MMDS 

and cable TV operators worldwide.  The company is more widely known internationally and in the 

LPTV and MMDS markets. However, with the introduction of DTV in the US, VeltekÕs plans to 

produce new digital products have accelerated.  

        

William Brown, director of international sales and marketing, notes, "we are now working on 

segueing from the LPTV and MMDS markets into the DTV low- to medium-power market."  He 

also points out that Veltek has been in the digital business for many years. "When it comes down 

to it, we were one of the first MMDS equipment manufacturers to come up with digitally 

compressed transmitters."

        

Veltek’s NTSC systems include a  solid-state 1,000 watt UHF and VHF transmitter.  They claim 

that their use of fewer, more powerful transistors ensures higher MTBF (mean-time between 

failure) and optimized performance by reducing system complexity.  Veltek  also manufactures 

microwave systems in the 13 to 18 Ghz range.

        

MDS International is a French company whose products have been traditionally targeted to the 

short and medium range wireless communications market.  Their product line includes low-

powered UHF and VHF transmitters, microwave systems, and DTV encoders, receivers, and 

modulators for satellite systems.  MDS also manufactures high-powered, medium wave AM and 

FM broadcast transmitters.

        

Yet, because their transmitter line tops out at a mere 200 watts, only a small number of VHF 

broadcasters could utilize their systems to achieve the FCCÕs minimum power level 

requirements.

        

All of the equipment manufacturers mentioned also maintain a presence on the Internet.  Further 

information on specific products and companies can be found at the following addresses:





BEXT, Inc.              http://www.bext.com

Itelco                  http://www.itelco-usa.com

ITS Corp.               http://www.itscorp.com

Veltek Industries       http://www2.wintek.com/veltek/

MDS                     http://www.mds.fr