Technics ST-7300
¥ 29,800 (around 1976)
Commentary
FM/AM tuner equipped with 2 meter and Rec level check mechanism.
A Rec level check switch is installed so that the input level of the deck can be adjusted.
When this switch is turned on, a 440 Hz sine wave is generated at a level corresponding to a 50% variable length FM signal input.
Equipped with a signal strength meter that indicates the strength of signal radio waves and a center tuning meter that indicates the degree of tuning to the center frequency.
The stability is improved by adopting an IC with a built-in quadrature detection circuit for the detection stage, and the meter can indicate up to 60 dB input signal.
The antenna terminal is directly connected to the front end, reducing sensitivity, interference, and unwanted radiation.
The front-end section is equipped with an FET with excellent high-frequency characteristics at the first stage and uses a highly accurate 3-row varicon.
Consideration is given to transmitting the signal straight to the amplifier, such as adopting a Cebi Czech type low-pass filter.
Three 2-element ceramic filters with excellent group delay characteristics are used for the IF stage.
The amplifier circuit consists of five stages, all stages being differential.
A PLL IC is used for the MPX demodulation circuit.
The PLL uses a voltage-controlled oscillator to generate a 76 kHz signal, which is divided by 1/2 to obtain 38 kHz and divided by 1/2 to obtain 19 kHz. The phase difference with the pilot signal is detected, and the oscillation frequency and phase match with the pilot signal.
.JPG)
Model Rating
| Type | FM/AM Tuner |
| FM Tuner Section | |
| Receiving frequency | 76 MHz to 90 MHz |
| Sensitivity | 0.9 μ V (75 Ω) |
| Harmonic distortion factor (1 kHz, 100% modulation) | mono:0.2% stereo:0.4% |
| SN ratio (400 Hz, 100% modulation) | mono:75dB |
| Frequency characteristic | 20 Hz to 15 kHz + 0.2 -1.0 dB |
| Selectivity (IHF) | 75dB |
| Capture ratio | 1.0dB |
| Image interference ratio | 55dB |
| IF interference ratio | 85dB |
| Spurious interference ratio | 80dB |
| AM suppression ratio | 55dB |
| Stereo separation | 45dB(1kHz) 35dB(10kHz) |
| Leak Carrier (19 khz / 38 khz) | -60dB |
| Antenna terminal | Unbalanced : 75 Ω |
| <AM Tuner Section> | |
| Receiving frequency | 525 kHz to 1605 kHz |
| Sensitivity (S/N ratio 20 dB) | 30 μ V |
| Selectivity | 20dB |
| Image interference ratio (1000 kHz) | 45dB |
| IF Disturbance Ratio (1000 kHz) | 40dB |
| <General> | |
| Output voltage | 0.5V |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 9W |
| External dimensions | Width 410x Height 140x Depth 296 mm |
| Weight | 4.0kg |
| Attachment | Feeder antenna Connection code |