TBA120 demodulator circuit The TBA120 Series ICs provide a high-gain limiting IF amplifier and a quadrature coincidence detector in one package. These ICs are primarily intended for extraction of TV intercarrier sound, which (in Europe) is frequency modulated onto a 5.5MHz or 6MHz subcarrier. The TV waveform constitutes an extreme interfering signal, and the TBA120 provides superior performance in comparison to early Foster-Seeley and Ratio Detector systems, with a considerable reduction in component count. TBA120 as AM demodulator. Equivalents are SN76660N (TI) and S041P (the latter is a low power version). It is in fact a CW/SSB/AM-multimode-detector, but the BFO line is connected to the signal from the IF. Believe I tested it in my Drake 2-B. Please note that TBA120AS, TBA120S, TBA120C, TBA120D etc are different and may not function satisfactorily in this construction. It is also suggested the change for use as SSB detector, but it is an old device and the circuit has more interest as a reference IF level is supposed to be maximum 50mV RMS. MC1351 should not have more than 10-20mV, and TDA1576 is overloaded with higher levels than 100mV RMS. NE/SA604/614 could also well be used, but have not been tested. The TBA120U is an i.f. amplifier with a symmetrical FM demodulator and an a.f. amplifier with adjustable output voltage. The a.f. amplifier is also provided with an output for volume control and an input for VCR operation. TBA120 demodulator circuit wiring diagram
TBA120 demodulator circuitThe TBA120 Series ICs provide a
high-gain limiting IF amplifier and a quadrature coincidence
detector in one package. These ICs are primarily intended for
extraction of TV intercarrier sound, which (in Europe) is frequency
modulated onto a 5.5MHz or 6MHz subcarrier. The TV waveform
constitutes an extreme interfering signal, and the TBA120 provides
superior performance in comparison to early Foster-Seeley and Ratio
Detector systems, with a considerable reduction in component
count.
TBA120 as AM demodulator. Equivalents are SN76660N (TI) and
S041P (the latter is a low power version). It is in fact a
CW/SSB/AM-multimode-detector, but the BFO line is connected to the
signal from the IF. Believe I tested it in my Drake 2-B. Please
note that TBA120AS, TBA120S, TBA120C, TBA120D etc are different and
may not function satisfactorily in this construction. It is also
suggested the change for use as SSB detector,but it is an old
device and the circuit has more interest as a reference IF level is
supposed to be maximum 50mV RMS. MC1351 should not have more than
10-20mV, and TDA1576 is overloaded with higher levels than 100mV
RMS. NE/SA604/614 could also well be used, but have not been
tested.
The TBA120U is an i.f. amplifier with a symmetrical FM
demodulator and an a.f. amplifier with adjustable output voltage.
The a.f. amplifier is also provided with an output for volume
control and an input for VCR operation.
TBA120 demodulator circuit wiring diagram
The input and output of the TBA120U are especially designed for
LC-circuits, but the input can also be used with a ceramic
filter.
TBA120U demodulator
TBA120 radio receiver for medium and long rf bandsUsing
electronic diagram below can be built a very simple radio receiver
for medium and long rf bands.Tuning stage of the receiver also
serves as active antenna that can be favorably positioned to get
the best reception possible. Circuit is completely separate from
the receiver, which consists of demodulator that provides
audio-frequency output. Plastic case of the antenna input circuit
contains a tuning coil designed on a ferrite bar (L2) and a double
diode varicap. Antenna signal is transmitted to the tuning stage
via a transistor (T1) repeatedly emitter ensuring a high impedance
output signal to the modulator.Received signal is amplified by the
stage forming active antenna, but a part of the integrated circuit
forming TBA120 modulator. L2 coil emitter serves as a shock to L3
disengages T1 and voltage supply agreement, and thereby prevents
shorting the RF output signal of the active antenna. L4 does the
same thing for the demodulator .Potentiometer P2 T3's gain sets
that provide a level of output signal compatible with the input
necessary for any amplifier.With the exception of L1, coils can be
used for standard shocks coils. L1 consists of 250 turns of
enamelled copper wire of 0.2 mm diameter, long-wave range, and 80
turns of enameled copper wire of 0.3 mm diameter (for medium waves)
that is wrapped on a ferrite bar length about 20 cm and a diameter
of 10 mm. Positive feedback loop is connected to an outlet of the
coil located at one
quarter the number of turns from the end of the ground. Circuit
Diagram:
