Two-Tone Rf Test Oscillator

Construction The network is most con- veniently constructed on the ready-made PCB Type 87109 shown in Fig. 5. The values of the components given in the parts list pertain to cross-over frequencies of 500 Hz and 5,000 Hz. Different frequencies may be calculated with the aid of the Linkwitz formulas in Ref. 4. In several places, capacitors are shown in parallel and resistors in series: this is done to enable the use of as many components of the same value as possible. As usual, the choice of capaci- tors is determined mainly by their loss factor and cost, which This test oscillator is useful to ensure optimum operation of RF amplifier stages designed to work on the short-wave bands. Based on two crystal oscilators, it provides considerable output power (10 to 100 mW) to enable measuring intermodulation characteristics of high level and RF power stages. The quartz crystals used here not only serve as the frequency deter- mining elemen1 (2...20 MHz), but also as output filters to pre-...