Kenwood KR 4140 (1970)
A solid-state FM/AM receiver from Kenwood’s early 1970s lineup, offering balanced performance and comprehensive tuning capabilities.
Overview
The Kenwood KR-4140 is a stereo FM/AM receiver manufactured by Kenwood, originally sold under the TRIO brand as the TRIO KR-4140. Introduced around 1970, it was priced at ¥66,800 in Japan. This receiver delivers detailed audio performance with a full suite of sound adjustment features and robust tuner sections for both FM and AM bands.
Specifications
| Product type | FM/AM Receiver |
| Music Power (IHF) | 80W (4 Ω), 58W (8 Ω) |
| Effective power Single Channel Operation | 33W/33W (4 Ω), 24W/24W (8 Ω) |
| Effective power Both Channel Operation | 21W/21W (4 Ω), 18W/18W (8 Ω) |
| Harmonic distortion factor | 0.8% or Less (Rated Output), 0.2% or less (-3dB at rated output) |
| Cross modulation distortion factor | 0.5% or Less (Rated Output), 0.2% or less (-3dB at rated output) |
| Frequency characteristic Main input | 15 Hz to 50 kHz ± 1.5 dB |
| Frequency characteristic Aux | 20 Hz to 40 kHz ± 1.5 dB |
| Output Bandwidth (IHF) | 18 Hz to 30 kHz |
| Damping factor | 50 (8 Ω) |
| Input Sensitivity / Impedance Phono1, 2 | 2.5mV/50k Ω |
| Input Sensitivity / Impedance Mic | 1.8mV/100k Ω |
| Input Sensitivity / Impedance Aux, Tape play | 150mV/100k Ω |
| Input Sensitivity / Impedance Main in | 100mV |
| Recording and re-output (at rated output) Pin | 150mV |
| Recording and re-output (at rated output) Din | 30mV |
| SN ratio (rated input) Phono1, 2 | 65 dB |
| SN ratio (rated input) Mic | 58dB |
| SN ratio (rated input) Aux, Tape play | 75 dB |
| Tone control | ± 10 dB (100 Hz), ± 10 dB at 10 kHz |
| High filter | -10dB(10kHz) |
| Low filter | -7dB(100Hz) |
| Loudness control | +10dB(100Hz), +5dB(10kHz) |
| FM Tuner Section Antenna impedance | 300 Ω balanced / 75 Ω unbalanced |
| FM Tuner Section Sensitivity (IHF) | 1.8 μ V |
| FM Tuner Section S/N | 65 dB or more |
| FM Tuner Section Distortion Factor (400 Hz, 100% modulation) Stereo | 0.8% or less |
| FM Tuner Section Distortion Factor (400 Hz, 100% modulation) Mono | 0.5% or less |
| FM Tuner Section Capture Ratio (IHF) | 2.5dB |
| FM Tuner Section Selectivity (IHF) | 55 dB or more |
| FM Tuner Section Image ratio | 70 dB or more |
| FM Tuner Section IF Rejection | 100dB |
| FM Tuner Section AM suppression | 50 dB or more |
| FM Tuner Section Harmonic spurious response | 70 dB or more |
| FM Tuner Section Stereo separation | 35 dB or More (1 kHz), 25 dB or More (10 kHz) |
| FM Tuner Section Subcarrier suppression | 40 dB or more |
| FM Tuner Section Front end | 2 FET, 4 Series Varicon |
| FM Tuner Section IF Stage | 2 ic, Mechanical Filter |
| AM Tuner Section Antenna | Built-in high sensitivity ferrite bar antenna |
| AM Tuner Section Sensitivity (IHF) | 15 μ V |
| AM Tuner Section Selectivity (IHF) | 25 dB or more |
| AM Tuner Section Image ratio | 70 dB or more |
| AM Tuner Section IF Rejection | 70 dB or more |
| AM Tuner Section Front end | 3 Series Variable Capacitor |
| Semiconductor used | Transistor: 36, FET: 2, IC: 2, Diode: 33 pcs |
| Power | 100 VAC / 117 V, 50Hz/60Hz |
| Power consumption | 120W at maximum output, 20W (no signal) |
| External dimensions | Width 424 x Height 141 x Depth 314 mm |
| Weight | 9kg |
Design
The KR-4140 includes sound adjustment functions such as tone control, low and high filters, and loudness control. It features a tape monitor function and an FM muting mechanism in the tuner section to suppress noise during weak signal reception.
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