Powerline Carrier Receiver Tune-Ups;

Easy With 90.04 Attenuator

For years, performing tune-ups, calibration and adjustments on powerline carrier receivers has been difficult due to the lack of equipment available for the job. That changed with the introduction of the optional attenuator for our popular Model 90 High Level Signal Source.

Known as the Model 90 Option 04, the attenuator is built into the lid of a Model 90. The attenuator can be ordered as an option with a Model 90 or ordered separately to be retrofitted to an instrument that is already in the field.

Many applications, such as setting discriminators and powerline carrier receiver sensitivity require test signals with stable frequencies and precise low amplitude control. Calibrating carrier level indicators and setting carrier level alarm points also require low level signals. Frequency stability and accuracy are inherent with the direct digital synthesis of the Model 90. The need has been low amplitude level control.

The Model 90 Signal Source is capable of low output amplitudes required by these applications. However, the LEVEL control on the Model 90 is a course adjustment and provides limited low amplitude resolution. It was in response to this need that the Option 04 Attenuator was designed.

The Option 04 is a 3-range attenuator using a combination of resistive and transformer voltage divisions. When driven with a nominal 10 volts from the Model 90 RF OUT connector, the attenuator output can be adjusted continuously from 3.0 to 30.0 millivolts, 30 to 300 millivolts and 0.30 to 3.00 volts. A 3-½ turn potentiometer allows easy setting of the desired output level within each range. The RMS output level is indicated on a 3-digit liquid crystal display. The displayed level is accurate to +/- 5% over the frequency range of 15 to 500kHz and all levels into loads of 27 W or greater.