NRG WORKSHOP....THE 4-WATT PLL-PRO III RF SECTION SCHEMATIC
A Broadband 4 watt VHF FM design featuring balanced oscillator-doubler/passband driver and output
The RF section of the PLL-PRO III Hi-Gain 4 watt Transmitter kit. Large picture.
If you are interested in VHF RF electronics then here is one of the most versatile 4 watt Oscillator/Doubler/Driver/Output circuits currently available. It has the advantage of frequency doubler designs--total isolation of the oscillator from the aerial output socket. It also shares the benefits of a spectrally pure output signal associated with 'at frequency generation' designs, due to the balanced frequency doubling oscillator combined with a critically shaped passband regenerative driver. Unlike 'at frequency' oscillator designs however, there is no hum, no frequency pulling by aerial loading, and no tendency for the whole circuit to just turn into one unstable 'power oscillator' unit! Unlike frequency doubler designs of the past, this 4 watt transmitter has only one RF adjustment and that is the VCO trimmer capacitor, VC1. The NRG 4 watt PLL-PRO III RF circuitry has received acclaim from many engineers for it's high power output, stability and spectral purity.