Marantz Model120
¥ 123,400 (around 1972?)
Commentary
FM/AM tuner developed based on the idea of reproducing Model10B with transistor.
With a built-in small oscilloscope, it can not only display input sensitivity and minimum distortion point for tuning, but can also be used by switching between multi-pass, audio and external in 4 ways.
The tuning knob uses the traditional gyro-touch tuning.
The muting circuit is designed to operate by three types of inputs.
The first is related to the strength of the input signal, the second is related to the noise state of the detection circuit, and the third is related to the DC component of the detection output. These three components are appropriately combined to suppress inter-station noise.
A dedicated circuit using a transistor is mounted to eliminate noise when the switch is turned ON / OFF or detuned.
On the front end, RF amplification by FET is employed, and it is applied to the mixer stage of FET through RF filter of triple tune.
Because the stage between RF amplification and mixing is triple tuned, it is a 5 series varicon.
Attention has been paid to the electrical and thermal stability of the mixer stage. By minimizing the drift, no AFC circuit is required.
The IF amplifier stage consists of seven stages including an 8-element ceramic filter and an IC limiter stage.
The ceramic filter is used in combination with one that has exactly the same phase characteristics, and the degree of distortion and separation is minimized.
The limiter includes 3 stages of symmetric type using gold bond type diode, and unnecessary AM part is removed by narrowing the dynamic aperture.
The output is taken out by an emitter follower.
The stereo demodulator is composed of 11 elements and 6 diodes. After switching, it is amplified by a 2-stage NF amplifier, is filtered by a low-pass filter and extracted by an emitter follower.
The audio amplifier is a 2-stage NF type.
The rear panel is equipped with muting level switches, Attenuator ON/OFF switches, output level switches, and an oscilloscope focus adjustment knob.
In addition, a QUADRADIAL connector is installed so that it can be used for 4 chFM broadcasting.
Model Rating
| Type | FM/AM Tuner |
| FM Tuner Section | |
| Tuning frequency range | 76 MHz to 90 MHz |
| Practical sensitivity (IHF) | 2.3 μ V |
| Selectivity (IHF) | 60dB |
| Capture ratio | 1.6dB |
| Image interference ratio | 90dB(88MHz) |
| Signal-to-noise ratio | mono:70dB stereo:60dB |
| Total harmonic distortion factor | mono:0.15% stereo:0.3% |
| Frequency response (50 μ sec, de-emphasis) | ± 1 dB (50 Hz to 15 kHz) |
| Stereo separation | 42dB |
| <AM Tuner Section> | |
| Tuning frequency characteristic | 535 kHz to 1605 kHz |
| Practical sensitivity | 20 μ V |
| Selectivity | 26dB |
| Image interference ratio | 70dB(1400kHz) |
| Signal-to-noise ratio | 46dB |
| <oscilloscope section> | |
| <Vertical Amplifier> | |
| Deflection Sensitivity | DC:290mV/cm AC:65mV/cm |
| Input impedance | 420k Ω |
| Input Capacitance | 30 pF or less |
| Maximum Permissible Input Voltage | 100Vp-p(AC or DC) |
| <Horizontal Amplifier> | |
| Deflection Sensitivity | DC:400mV/cm AC:65mV/cm |
| Input impedance | 420k Ω |
| Input Capacitance | 30 pF or less |
| Maximum Permissible Input Voltage | 100Vp-p(AC or DC) |
| <General> | |
| Pwer | 100 VAC / 120 V / 200 V / 220 V / 240 V, 50Hz/60Hz |
| Power consumption | 40W |
| External dimensions | Width 391x Height 147x Depth 300 mm |