Security Technology Inc. of Vienna used the symbol SEXE in its first public offering, perhaps hoping to convince over-the-counter buyers that the stock has appeal.

However, more fundamental factors must have accounted for Sec Tech's sale of enough 15-cent shares to raise almost $1.7 million with which it plans to test and market its first product -- a pocket-sized personal security alarm and transmitter.

The firm calls its product PAL, for Personal Alarm and Locator system, and hopes to bring it to market within six months.

A company spokesman could not be reached for comment, but the prospectus says the device uses a "coded acoustic technology" to emit a loud alarm siren while simultaneously transmitting a signal to a remote receiver.

Just as a telephone system uses different sound tones to identify each digit of a phone number, PAL generates a coded acoustic signal that identifies a particular transmitter.

A receiver can pick up this signal within a 350-foot radius, and can trigger a siren and lights, and forward the alarm to a security guard or police station, the prospectus says. The information allows security authorities to send help and provides details, about the person carrying the PAL.

Sec Tech forsees use of the system on campuses, in prisons, commercial and residential areas and in hospitals to alert doctors and nurses to medical emergencies.

The PAL transmitter should cost about $25 to $30 initially, while receivers should range in price from $100 to $250, the prospectus says, depending upon application.dollars, the company estimates

Eventually, Sec Tech hopes to use the acoustic technology to develop other security products, such as wireless alarms to protect homes, stores and expensive equipment.

The prospectus notes that more than 1,000 firms manufacture security equipment and devices. But the company believes PAL is the only device to combine a silent alarm signal and a loud local siren.

Sec Tech was founded in February 1980 as Wackenut Research, a joint venture between Wackenut Corp., one of the largest security companies, and ENSCO Inc., a private research and development firm in Springfield.

ENSCO has designed and developed technology to detect and analyze signals generated by various sources, primarily for national defense. Its systems are used to locate signals from submarines, ships, aircraft and nuclear explosions.

ENSCO bought Wackenut's 80 percent share of the company in August 1981 to concentrate on private security, the Sec Tech prospectus says. Last year, ENSCO was renamed T. H. Wallace Inc. It is now a holding company with equity positions in several firms, including 42 percent of Sec Tech.

Wackenut, with 1983 sales of $234 million, retains the rights to market, sell and distribute Sec Tech's products exclusively for three years, and non-exclusively thereafter.

The prospectus lists total unaudited assets of $140,630 and liabilities of $841,342 as of March 31. The company reports cumulative net sales of $14,672 and net losses of $1.5 million from its founding to the end of March.

Sec Tech said it conducted a successful field test of PAL at San Quentin Prison in California, last May. It planned to begin field tests at other locations, including Catholic University of America, within six months after the public offering.