Detecting Efficiency and Current Amplification of the Resistance-capacity Coupled, Two-tube Amplifier.—Test of Hulburt's formula, giving a relation between detecting efficiency and the constants of the tubes and circuits, has been extended to 6,000 meters. The detecting efficiency is defined as $\frac{b_0}{A^2}$, where $A$ and $b_0$ are the amplitudes, respectively, of the input grid potential and of the rectified component of the output plate current. It was found that (1) for any wave-length the relation between $b_0$ and $A^2$ is linear; (2) for constant wave-length, $\frac{b_0}{A^2}$ varied with the coupling capacity in accordance with the formula within about 10 per cent., being practically constant for capacities greater than 200 $\mu \mu F$; (3) for constant capacities, $\frac{b_0}{A^2}$ varied with wave-length for ranges 1,100 to 2,500 and 2,500 to 6,000 meters in fair agreement with the theoretical curve. The current amplification, $n=\frac{b_0}{E{g}^2}$, where $\mathrm{Eg}$ is the amplitude of the potential impressed on the grid of the second tube, was found to be independent of the wave-length to 6,000 meters.

Plate current of vacuum tube (Radiatron UV 201) was found to be sensitive to the external temperature.

Close

PrevNext

View figure in article