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Which of these is true of a capacitor with a negative temperature coefficient
As temperature rises it will increase its cpacitance
As temperature falls it will decrease its cpacitance
As temperature rises it will decrease its cpacitance
As temperature rises it will remain at the same cpacitance
In a tuned ciruit the frequency is observed to rise when the temperature increases. The change in frequency could be reduced by using
A capacitor with a positive temperature coefficient
A capacitor with a negative temperature coefficient
An inductor with a positive temperature coefficient
A combination of a capacitor with a positive temperature coefficient and an inductor with a positive temperature cofficient.
Which of these methods would be least effective in controlling the temperature of a crytal.
Place the crytsal in a thermostatically controlled oven.
Provide ventilation holes to let excess heat escape
Have a fan that constantly transfers air from the PA compartment to the crystal oscillator compartment.
Have a fan that transfers heat from the crystal area when the temerature increases above a set level.
Which of these capacitors would be most stable in an oscillator circuit
Ceramic decoupling capacitors
COG/NPO capcitors
Electrolytic capacitors
Myler capacitors
A VFO shows an increase in frequency as the temperature rises. To improve the stability:
A negative coefficient capacitor could be soldered in parallel with the main tuning capacitor
A positive coefficient capacitor could be soldered in parallel with the main tuning capacitor
The airwound coil could be replaced with a smaller coil wound on an adjustable ferrite core
The coil could be increased in size using wider spacing between the turns.