The Model 427 Output Meter is designed for the efficient indication of the audio frequency output of a radio set as well as miscellaneous voltage measurements. The ranges of 2, 10 and 50 volts have been selected to take care of all requirements of a modern receiver. A 0.1 MF. condenser is connected to the common terminal and the other side of the condenser is brought to a jack marked "COND." This serves to block direct current in any circuit where this may be required.

When used across the voice coil of low impedance dynamic speakers, the 2 volt range is most desirable, no condenser being required. Medium impedance speakers will give best results on the 10 volt range and may or may not require the use of a condenser, depending as to whether or not the direct current has been filtered from the circuit.

The high range is suitable for connecting either across a magnetic speaker, or directly from the plate of an output tube to ground, to cathode or to filament. Since this circuit is in shunt to the plate supply, it is necessary to connect with the condenser in series in order to block direct current from flowing and read the audio component only.

Test leads are supplied for use with this instrument. Where connections must be made to the plate of of an output tube, the single contact adapter packed with this instrument will be found very convenient.

This instrument will give best results when used with a high grade service oscillator, delivering sharp, cleanly modulated signal of known frequency.