IB Preamp

[lucifer]

Hi all,
I was wondering which type of preamp is better for an IB detector:
low impedance transistor based preamp, or a high impedance preamp using an opamp.
The first one has a better impedance matching with the coil and the result is more power transferred according to the Maximum power transfer theorem.
The second option would have a better power efficiency because of the high impedance of the opamp.
Which of the two options has better sensitivity/stability/noise immunity?

[Carl-NC]

Impedance matching and power transfer are of no interest with detector coils. You will get better results with a high impedance opamp.

- Carl

[lucifer]

Thanks Carl! I was surprised that so many IB circuits use transistor based amplifiers. In the Magnum circuit description is said: "The receive coil L2 is untuned; this, coupled with the low impedance input load of TR2 ensures the predictable phase response required for reliable discrimination."
I've read similar text in other documents, always mentioning the "low impedance" of the preamp.