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mack you have no need to track the pass transistor with that circuit,
the circuit itself is a low voltage low source impedance regulated power supply, it regulates any changes in ( vcc to the bias circuit, pass transistor conduction due to thermal effects, load drawn by the finals, )
the one sensing transistor does a decent job of tracking the finals,
its not perfect but its more than acceptable for any conventional bipolar hf /vhf/uhf amplifier,

the double tracking seems to improve the stability of simple regulator fed pass transistor setups as found in the majority of hf radios using bipolar output devices and the lower priced all band bipolar hf amplifiers,

if manufacturers gave us an extra terminal for a matched on die sensing diode we could really get a grip on amplifier operating point. __________________

[QUOTE="bob85, post: 164764, member: 18"] mack you have no need to track the pass transistor with that circuit, the circuit itself is a low voltage low source impedance regulated power supply, it regulates any changes in ( vcc to the bias circuit, pass transistor conduction due to thermal effects, load drawn by the finals, ) the one sensing transistor does a decent job of tracking the finals, its not perfect but its more than acceptable for any conventional bipolar hf /vhf/uhf amplifier, the double tracking seems to improve the stability of simple regulator fed pass transistor setups as found in the majority of hf radios using bipolar output devices and the lower priced all band bipolar hf amplifiers, if manufacturers gave us an extra terminal for a matched on die sensing diode we could really get a grip on amplifier operating point. __________________ [/QUOTE]

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