he Ameco VFO-621 is a Variable Frequency Oscillator to be used with the Ameco TX-62 Transmitter or any other 50, 144 or 220 Me. transmitter that is designed to operate with 8, 12 or 24-25 Me. crystals. The Ameco VFO-621 uses the superior HETERODYNE principle. The variable frequency oscillator operates at a low frequency. It is then heterodyned to 24-26 Me. by means of a crystal controlled oscillator and mixer. This permits operation of the oscillator with one-third of the usual multiplication. The lower multiplication, combined with the lower oscillator frequency, permit a STABILITY and keying quality almost non-existent on the three VHF bands. There is no chirp with keying. The warm-up time is very short, as both oscillators use transistors. The internal AC power supply is Zener Diode regulated. The dial scale is calibrated for 50-52, 144-148 and 220-225 Me. The scales are long, open and easy to read. For mobile operation, terminals are provided for external DC supplies (6 or 12 volts for the filaments and 100 to 150 volts for the plates). The cabinet height and finish match the TX-62 transmitter. It is 6" high, 5" wide and 7-1/2" deep.