Functional description

It contains several function units, which enable designing and assembling of efficient AM tuners. Caused by

internal voltage stabilization characteristics are rather independent from supply voltage.

The RF input signal reaches via a controllable and overdriving proof preselector stage a balanced mixer. By

means of a RF - signal generated by a separated oscillator the input signal is transported into IF. Multiplicative

mixing causes only few harmonic content. Gain control is carried out by means of two separated feedback control

loops for preselector stage and IF amplifier. By these a loop bandwidth of approximately 100 dB is obtained. The

control voltage of the IF - amplifier can be used to drive a moving - coil instrument (field strength indicator). The IF

amplifier consists of 4 amplifier stages, the first, second and third can be controlled. The bandwidth of the IF

amplifier is approximately 2 MHz and on that account sufficient for usual IF frequencies in the AM range of

approximately 460 kHz.

The symmetrical arrangement of the entire circuitry guarantees well oscillating. The bridge of the mixer avoids

direct breakdown.

Absolute maximum ratings

min

max

unit

Supply voltage

4.5

15.0

V

Junction temperature

150

°C

Ambient operating temperature

-15

80

°C

Storage temperature

-40

125

°C

Total thermal resistance

120

K/W

Recommended operational conditions

min

max

unit

Supply voltage

4.5

15

V

Ambient operating temperature

-10

70

°C

12/95

3

TCA 440 / T