TM 9-6695-274-14
Figure 1-70. Krohn-Hite, Model 3202R, Variable Filter.
Krohn-Hite, Model 3202R, Variable Filter (fig. 1-70) is a solid state variable electronic filter with cutoff frequencies
continuously adjustable over the frequency range from 20 Hz to 2 MHz. The pass-band gain is unity (0 dB), with an
attenuation rate of 24 dB per octave outside the pass-band. Maximum attenuation is greater than 80 dB and the output
hum and noise is less than 100 pV. Model 3202R consists of two separate filters mounted in a single cabinet isolated from
each other with independent power supplies, and input and output connectors. When these two filter channels are
switched to the same mode of operation and connected in series with both dials set to the same cutoff frequency, model
3202R will function as a high-pass or low-pass filter with an attenuation rate of 48 dB per octave. If the two channels are
connected in series, and one channel is operated in the low-pass mode and the other channel in the high-pass mode,
model 3202R will function as a band-pass filter with attenuation rate of 24 dB per octave outside the pass-band.
Figure 1-71. Hewlett-Packard, Model 415E, Standing Wave Ratio (SWR) Meter.
Hewlett-Packard, Model 415E, Standing Wave Ratio (SWR) Meter (fig. 1-71) is a high gain amplifier, tuned to an audio
frequency, with a square-law calibrated meter readout. Model 415E is designed for use with square-law detectors in the
measurement of SWR and attenuation. In addition, because of the high-sensitivity and tuned amplifier, it can be used as a
null detector for audio-frequency bridges.
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