The 2040 series of Signal Generators cover the frequency range 10 kHz to 5.4 GHz with three models: 2040 (10 kHz to 1.35 GHz), 2041 (10 kHz to 2.7 GHz) and 2042 (10 kHz to 5.4 GHz). A dot matrix display with soft key selected screen options allow flexibility of operation and ease of use. The output may be amplitude, phase, or frequency modulated with pulse modulation available as an option. Modulation is available using a combination of up to two external signal inputs and a built-in LF source (a second internal source is optional). Microprocessor control ensures that the instruments are flexible and easy to use and allows programming by the General Purpose Interface Bus (GPIB), The GPIB is designed to IEEE Standard 488.2 and is a means of sending commands to an instrument, via a data bus, from a remote controller or personal computer. The instruments can therefore be used manually or as part of a fully automated test system. MAIN FEATURES Operation Selection of parameters on the screen may involve one or more of the numeric, hard or soft keys or the rotary knob. Hard keys have single or dual functions which remain constant throughout, whereas soft keys have functions dependent on the present mode of operation. Parameters may be set to specific values by numeric key entry, while values may be varied in steps of any size using the if/ll keys or altered by moving the knob, set to a particular sensitivity. The SIG GEN, LF, SWEEP, MEM (memory), Δ (delta) and UTIL (utility) menus are selectable, at any point of operation, via the keys below the display panel. Within the display, the soft key functions are indicated by labels which appear alongside the keys situated at either side of the display panel. Display The display is a dot matrix liquid crystal panel, with backlighting. Carrier frequency, modulation and RF level are shown in horizontal regions on the principal screen. The display features 11-digit resolution for carrier frequency, 4-digit for RF level and 3-digit for modulation, with unit annunciators. Contrast may be varied, using the control knob, to optimize the viewing angle. Differing lighting conditions may be accommodated using the backlight intensity function, variable from no backlight to full intensity. A full graphical display test is available, refer to the Service Manual. Frequency selection Carrier frequency is selected via the soft key option on the SIG GEN display and direct entry via the keyboard. Alternatively, selection may be made via the General Purpose Interface Bus (GPIB). Frequency resolution is 0.1 Hz across the band. Carrier frequencies can be stored in a non-volatile memory with complete recall when required. An ON-OFF key is provided to completely disable the output Output RF output up to +13 dBm can be set by direct keyboard entry with a resolution of 0.1 dB or better over the entire range. A high output option is available to extend the maximum calibrated level to +19 dBm on the 2040 instrument. An extended hysteresis facility allows for extended electronic control of RF output level without introducing mechanical attenuator transients when testing squelch systems. A low intermodulation mode can be selected which disables the RF levelling system and improves the intermodulation performance when combining the outputs of two signal generators. A choice of calibration units is available to the operator and provision is made for the simple conversion of units (for example, dBm to μν). Calibration data for the output level is held in memory and may be altered from the front panel or over the interface bus. The output level can be offset by up to ±2 dB by keyboard entry. Offsets from the calibrated value may be used to compensate for cable or switching losses external to the generator. This facility can be used as a means of deliberately offsetting the output level to ensure that all generators in an area give identical measurements. While using the offsetting facility, the principal calibration of the generator is not lost and may be returned to at any time. An electronic trip protects the generator output against reverse power of up to 50 W, preventing damage to output circuits when RF or DC power is accidently applied.