AF-1 Audio Frequency Meter. For determining frequency from 20Hz to 100 kHz. Set slector switch to proper range, feed signal to input terminals and read frequency on meter. Simpson 200 microamp meter with 2 scales (0-100 and 0-300), that read in conjunction with the 7-position slector switch to give full scale readings of 100, 300, 1000, 3000, 10,000, 30,000 and 100,000 kHz. The 1:3:10 ratio is maintained and each range has an individually calibrated control. A signal voltage anywhere between 2-v and 300-v can be fed directly into the instrument and a change in signal voltage between these limits will not affect the meter reading. Input wave shape not critical; will read either sine or square wave. Tubes: 6SJ7 amp/clipper, 6V6 amp/clipper, 6H6 meter pulse rectifier, 6X5 power supply rectifier, and OD3/VR-150 voltage regulator. 15 lbs. 1952 price: $34.50.