YAMAHA T-4D

Commentary

FM/AM tuner equipped with LED-based tuning system.

It uses the optical balance type tuning meter used in the T-9, etc.
This tuning meter has green LEDs on the left and right side of a red dial indicator LED. When the brightness of the green LEDs matches, accurate tuning is indicated.

The front-end section consists of a high-precision wide-air-gap 3-varicon and an RF amplifier using a low-noise J-FET.

The IF stage consists of a 4-element equivalent ceramic filter and a 3-stage differential amplifier IF circuit with a current limiter.
The detector stage is composed of a cascode-connected wide-range balanced -range balanced type ratio detector to obtain excellent characteristics.

The MPX stage uses Yamaha's original DC-NFB circuit based on a high-speed DC amplifier, a PLL subcarrier generation circuit using a balanced type single-ended phase detector, and a pilot cancellation circuit.

The AM tuner section consists of a double varicon, a self-excited converter, an IF coil + ceramic filter, and a superheterodyne using a high-gain IF-IC. Combined with a high-Q antenna coil and a low-impedance, low-gain loop antenna, the AM tuner section realizes a low distortion factor.

FM uses an interference detection method and AM uses an input level detection method, so that there is no noise between stations.

Model Rating

Type	FM/AM Tuner
FM Tuner Section
Practical sensitivity (mono)	300 Ω : 1.7 μ V (9.8 dBf) 75 Ω : 0.85 μ V (9.8 dBf)
Capture Ratio (IHF)	1.5dB
Effective selectivity (IHF)	55dB
Signal-to-noise ratio	stereo:84dB
Distortion Factor (1 kHz)	mono:0.1% stereo:0.2%
Stereo separation	40dB(1kHz)
Frequency characteristic	30 Hz ~ 15 kHz + 0.5 -1.5 dB
<AM Tuner Section>
Practical sensitivity (IHF)	10 μ V
Signal-to-noise ratio	55dB
Total harmonic distortion factor	0.3%
<Others>
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption	7W
External dimensions	Width 435x Height 92x Depth 305 mm
Weight	3.7kg