(Quantity 8) Location: Undergraduate Lab.Inv #
The 415E SWR Meter is a low noise, 1000Hz tuned amplifier and voltmeter, calibrated in dB and SWR. Designed for use with square law detectors, SWR attenuation and gain measurements are made easily and read directly from metered scales. Can also be used as a tuned amplifier for driving an X-Y recorder when making RF substitution measurements. The 415E has two outputs located on the rear-panel: a recorder output with 0 to 1 VDC into an open circuit and an AC amplifier output of 0 to 0.3 V rms (NORMAL mode), 0 to 0.8 V rms (EXPAND mode). The 415E has an internal precision 60 dB attenuator allowing it to operate over a 70 dB range in 2 or 10 dB steps. The sensitivity is 0.15 µV rms for full scale deflection at maximum bandwidth (1 µV rms on high impedance crystal input). The bandwidth is continuously adjustable from 15Hz for maximum sensitivity to 130Hz.
Hope to settle a dispute. A colleague is using an HP 415E ( with NO detector) to measure dB change of a voltage input. He is setting a reference, changing the input level, then reading the 415 expanded scale and reporting the value directly as the dB change. I contend that without a square law detector, he is wrong. The indication on the meter is only half the true dB change. This I can prove. He fires back (and it is so) that in the 415 manual, the calibration procedure sets reference, changes the input via a standard attenuator, and reads the error directly from the meter face and compares this to the manufacturers specs. I feel that the mfr test is in error. Shouldn't the reading be doubled since there is no detector??? Thanks
Thursday, October 28, 2004