YAMAHA CT-600
¥ 60,000 (around 1974)
Commentary
AM/FM stereo tuner with low distortion factor and high separation achieved by original MPX circuit
The FM front-end section uses two dual-gate MOS FETs with low noise and excellent high-frequency characteristics in the FM RF stage and mixer stage to improve cross-modulation, image interference ratio and spurious interference ratio.
A frequency number line type precision four series varicon is used for the tuning circuit.
The IF stage is designed with an emphasis on phase characteristics along with the front end. The circuit configuration that also includes circuit elements such as ICs and 4-element ceramic filters realizes high stability and excellent limiter characteristics.
The MPX circuit uses a high-precision IC to achieve a low distortion factor, and an LC-type low-pass filter sharply cuts unwanted residual signals such as carrier leakage.
By adopting a unique circuit in which the AFC is automatically turned off when the tuning knob is touched at the time of channel selection, and the AFC is turned on when the knob is released after synchronization with the receiving station. This circuit enables accurate reception from stations with strong to weak radio waves.
In addition, the AFC/STATION indicator lights faintly in the area where the station is located, and lights brightly when the AFC is turned on to indicate correct operation.
The signal meter is equipped with an AGC, and the pointer is moved linearly from weak electric field to strong electric field.
It also has a tuning meter.
The AM tuner section is composed of a triple tune system with a tuning circuit consisting of a triple varicon, ceramic filter, and two tuning coils. By improving the selectivity and image interference ratio, AM broadcasting is easily received and sound quality is improved.
A dedicated AGC circuit is also provided to enable clear reception even when strong input is applied.
It is equipped with a multi-path detection terminal, an FM muting switch, a high-blend filter that blends high frequencies to reduce noise, two fixed and variable output terminals, and an IF output terminal for 4-channel broadcasting.
Model Rating
| Type | FM/AM Tuner |
| FM Tuner Section | |
| Receiving frequency | 76 MHz to 90 MHz |
| Practical Sensitivity (IHF, 84 MHz) | 2.0 μ V |
| Chinese arrowhead's slope | 55 dB (5 μ V) 60 dB (10 μ V) |
| Image interference ratio | 90dB(84MHz) |
| IF interference ratio | 95dB(84MHz) |
| Spurious interference ratio | 95dB(84MHz) |
| AM suppression ratio | 55dB |
| Capture ratio | 1.5dB |
| Effective selectivity (IHF) | 75dB |
| S/N | mono:70dB stereo:66dB |
| Total harmonic distortion factor | mono:0.3%(400Hz) 0.6% (50 Hz to 10 kHz) stereo:0.5%(400Hz) 2.0% (50 Hz to 10 kHz) |
| Stereo separation | 40dB(400Hz) 28 dB (50 Hz to 10 kHz) |
| Frequency characteristic | 50 Hz to 10 kHz ± 1.0 dB 20 Hz ~ 15 kHz + 1.5 -3.0 dB |
| Subcarrier suppression ratio | 40dB |
| Muting signal level | 10 μ V |
| IF out level / impedance | 200mV/1k Ω |
| Multipath level / impedance | Vert : 10mV/55k Ω Horiz : 200mV/4k Ω |
| <AM Tuner Section> | |
| Receiving frequency | 525 kHz to 1605 kHz |
| Practical sensitivity (IHF, bar antenna) | 52dB/m, 25 μ V |
| Selectivity (1,000 kHz) | 30dB |
| Signal-to-noise ratio (80dB/m) | 45dB |
| Image interference ratio (1,000 kHz) | 70dB |
| IF disturbance ratio (1,000 kHz) | 60dB |
| Spurious interference ratio (1,000 kHz) | 70dB |
| Total harmonic distortion factor (80dB/m) | 0.8% |
| <General> | |
| Output Level / Impedance (1 kHz) * FM (400 Hz, 100% modulation) * AM (400 Hz, 30% modulation) |
Fixed FM : 600mV/5k Ω AM : 120mV/5k Ω Variable FM : 60 mv ~ 2V/1k Ω AM : 12 mv ~ 0.4V/1k Ω |
| Semiconductor used | Transistor : 31 FET : 2 Diode : 20 pcs Zener diode : 1 unit Light Emitting Diode : 3 IC : 2 Ceramic Filter (FM) 8 Elements Ceramic Filter (AM) 1 Element |
| Power outlet | Unswitched:500W |
| Rated power consumption | 10W |
| External dimensions | Width 436x Height 144x Depth 323 mm |
| Weight | 7.0kg |