"Poor phase noise not withstanding, the early PLLs did offer a few
advantages. Excellent frequency stability
without temperature compensation, broadband "general coverage"
tuning, and remote computer controllability
were enough to ensure that PLLs would soon replace LC oscillators in
nearly all commercial radios. Ten-Tec
jumped on the bandwagon too with the synthesized Paragon model.
When the Paragon was introduced, however, we were well aware of the
phase noise limitation, so we kept the
permeability-tuned, crystal-mixed Omni transceivers in the line for
serious contest-oriented operation in the HF
amateur bands. Eventually, a PLL based replacement for the
permeability-tuned-oscillator (PTO) was
developed for the Omni line. This PTO replacement overcame the phase
noise limitation of the PLL by
incorporating some of the same design techniques later used in the
modern Orion synthesizer design to be
presented here."
http://radio.tentec.com/cms-files/565_syn_article.pdf
73, Bill W4ZV
|