To overcome communications problems caused by last week's massive earthquakes in Mexico, news organizations and government agencies turned to new satellite earth stations small enough to pack into two large suitcases.

One such system is made in Fairfax by Telesystems, one of three arms of Comsat Technology Products, which in turn is a unit of Communications Satellite Corp.

Telesystems recently began shipping its TCS-9000 Transportable Earth Station, according to John M. Pientka, vice president of Telesystems' mobile-satellite systems division.

The station features a satellite dish 35 inches across and supporting equipment -- to translate signals, convert power from external sources and act as a traffic manager -- that stores neatly into two suitcases totaling 110 pounds. Until recently, the smallest transmission dish was about 10 feet across, and the supporting equipment filled a small trailer, according to Pientka.

The Magnavox Government & Industrial Electronics Co. subsidiary of North American Philips Corp. also offers a portable satellite earth station, the MX211T, with a dish less than 3 feet across and equipment that packs into two suitcases, according to Zenaido Quintana, director of marketing for the company's marine and survey system division.

CBS is using the MX211T in Mexico, he said. The MX211T is a modification of a shipboard unit. It has been available for about a year and a half, and 20 have been sold.

Phone calls placed through the Telesystems or Magnavox portable stations are transmitted to a satellite, which retransmits the signal at another frequency to one of 12 coastal earth stations owned and operated by telecommunications companies around the world; in the United States, Comsat is the company involved. From the coastal earth station, the signals are fed into telephone systems. The procedure is the same for telex communications, except the transmission ends up being fed into the separate telex network once it returns to earth.

The marketplace centers on customers needing high-quality data and phone communications from remote locations -- where phone lines don't exist or are inoperable -- on an as-needed basis, according to Pientka. He said customers so far have included oil exploration and service teams, foreign governments and U.S. government agencies.

The amount of interest from public-safety agencies -- especially for use during natural disasters -- surprised the company, Pientka said. And phone companies are interested in using the satellites to communicate with crews sent out to repair downed lines.

Pientka acknowledged that fiber-optic lines offer the biggest competition to satellite-based communications systems, and that fiber-optic setups are more efficient for high-volume, point-to-point communications. Satellite systems, on the other hand, are best for multi-point communications, one-way communications and low-volume communications, he said.

He also cited the adaptability of satellite systems -- the ability to reprogram the transponders, which receive and resend signals and change ground equipment. He said that his division's products use a lot of software, making it easier to upgrade the systems or tailor them for each customer's needs.

Pientka said that satellites are getting more powerful and could be made "smarter" -- that is, able to switch data to various users by using many smaller, more highly focused transmission beams rather than one large, diffused beam. The change would permit ground equipment to be smaller, he said.

The TCS-9000 was developed over the last eight months, mainly by six Comsat engineers, Pientka said. There is nothing patentable in the TCS-9000, according to Pientka, who added that his company "is not concerned with patents" because of the fast pace of technological innovation.

Telesystems obtained certification a few weeks ago from Inmarsat that the TCS-9000 meets its technical standards and therefore can use Inmarsat's chain of satellites. Inmarsat is a group of telecommunications agencies from 40 countries around the world that own and operate a system of satellites primarily for maritime communications.

Telesystems is the digital-products and systems-hardware arm of Comsat Technology Products. It produces mobile satellite systems -- such as the new TCS-9000 -- for areas "where you can't string wires," Pientka said.

A second part of Comsat Technology Products, the Network Products Division, engineers and markets Starcom, a satellite system designed to work especially in areas that have a large number of satellite dishes.

Amplica, the third CTP division, which is based on the West Coast, is split between defense work and manufacturing consumer products such as home satellite dishes.

Pientka would not say how many TCS-9000s have been sold, but he did say that he expects to sell between 50 and 70 of the transportable earth stations this year and at least 100 in 1986.

"I'd say the market is at least in the hundreds," he said. "No one believes that the market is this size -- but we keep taking orders," he said. The stations cost $38,000 each.

Half of the division's overall sales so far have been made to overseas customers, as have 80 percent of TCS-9000 sales, he noted.

Pientka said that he expects competitors to develop "me-too products" next year. He added that no further substantial reductions in size are expected beyond eliminating dishes for data-only transmission and shrinking the supporting equipment into a one-briefcase unit.

Telesystems has 320 employes, while Pientka's engineering and marketing division has 12. The division's 30-person production line is turning out 10 maritime and 20 TCS-9000 systems a month.

Having a portable earth station is one thing; paying for transmissions is another. Pientka said that data or voice transmissions involving phone lines cost the sender $10 a minute, and those involving telex, $4 a minute.