Standing Wave Indicator 415A

The 415A Standing Wave Indicator is designed for use with the 805A Slotted Line. It may also be used as a null indicator, or for bridge measurement, and provides a 75000 ohm input cirquit for this application.
The 415A consists of a high gain amplifier with very low noise level, operating at fixed audio frequency. Amplifier output is measurement with a Square-Law calibrated vacuum tube voltmeter. This meter reads direct in VSWR and in db.

Frequency: Normally 1,000 cps ±2%.  Plug-in units for other frequencies, 300 to 2,000 cps are available. Request unit 4119-42, and specify frequency. Amplifier “Q” is 20  ±5.

Sensitivity: 0.3 µv. gives full scale deflection. Equivalent noise level referred to input is 0.04 µv.

Calibration: For use with Square-Law detector. 60 db level covered in 6 ranges.  Accuracy ± 0.1 db per 10 db step.

Gain Control: Adjusts meter to convenient level. Range is approx. 30 db.

Input:  Connects to crystal rectifier or bolometer. Bias of 8 v. ±0.5 v delivers approx. 8.75 ma. to a 200 ohm bolometer or 1/100 ampere instrument fuse. 75,000 ohms for null measurement. One terminal at ground.

Here you find 392 models, 360 with images and 138 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Hewlett-Packard, (HP); Palo Alto, CA