계측기 판매전문 (주) 한일티엠입니다.

- Frequency range 1.5 MHz to 2 GHz
- Useful indications to 4 GHz
- LED indication of lock, level set and function
- Analogue display
- Incorporates three bandpass filters, a psophometric filter, and a deemphasis network
- Small, lightweight unit ideal for field use if battery version ordered
- GPIB version for systems use

The Automatic Modulation Meter model 257 has been designed to simplify the task of measuring amplitude and frequency modulation on signals in the range 1.5MHz to 2GHz. By eliminating the need to tune a local oscillator and make level adjustments the 257 speeds up measurements and reduces errors. Patented circuitry ensures that the meter always locks to the highest signal available ignoring spurious signals and harmonics.

AM and FM measurements can be made at full accuracy over the frequency range l.5MHz to 2GHz and with reduced accuracy and sensitivity to 4GHz. On FM, five ranges are provided with fullscale readings of 1kHz, 3kHz, 10kHz, 30kHz and 100kHz deviation. Peak positive, peak negative or mean deviation can be displayed. On AM five ranges give full scale readings of 1%, 3%, 10%, 30% and 100%. Peak, trough or mean of percentage modulation can be displayed.

For ease of measurement, three band pass filters with minimal upper cut-off frequencies of 60kHz, 15kHz and 3.5kHz, a psophcmetric filter or a 750µs de-emphasis network can be selected to filter the recovered modulation.

The different ranges and functions are selected by front panel push buttons with LED's providing positive indication of function.

The unit is small and lightweight, so making it ideal for field work, especially with the battery option installed, which will give at least 8 hours of continuous use before needing a recharge.

For automatic test facilities a GPIB option is available which provides remote control and interrogation of all functions. Note that the GPIB interface is not available if the battery option is fitted.