VICTOR/JVC T-7070

Commentary

This is the world's first FM stereo tuner in the Laboratory 7070 series that uses PLL circuits in three stages.

The T-7070 consists of three main circuits with PLLs. In addition to the MPX circuit, the local oscillator circuit and the detection circuit are PLLs.
The PLL detection circuit consists of a loop consisting of a phase comparator circuit, a low-pass filter, and a VCO (voltage controlled oscillator). The detection output is always synchronized with the phase of the IF signal. Since the PLL detection circuit operates in response to changes in the IF signal, it is hardly affected by temperature aging. Moreover, the differential gain characteristic (linearity of the detection characteristic) is flat within the lock range of the PLL regardless of the input level. Therefore, the output with less distortion can be obtained. In addition, the filter characteristic detects only signals within the lock range. The lock range automatically changes according to the input strength. The selectivity of weak signals can be increased without switching the bandwidth of the IF stage. There is AM suppression capability. It has advantages that cannot be obtained with conventional methods.
In addition, the T-7070 uses a local oscillator circuit as a PLL synthesizer and locks the IF signal, resulting in high fidelity and stability.

A newly developed SAW (Surface Acoustic Wave) filter is used for the selection element of the IF stage.
This filter applies the principle of transmitting a signal by means of vibration waves propagating on the surface of a piezoelectric element. The linear part of the group delay characteristic is twice as wide as that of a ceramic filter, and has the same selectivity.

The MPX stage has a built-in pilot cancellation circuit. In this circuit, a PLL circuit generates a pilot signal of opposite phase in order to remove the switching signal which is unnecessary for the decoder, and cancels it between the preamplifier and the decoder. This eliminates the need to attenuate 19 kHz with a low-pass filter for removing the unnecessary signal at the decoder output, thus improving the frequency and phase characteristics of the audio band.
In addition, the decoder circuit is reduced in distortion rate by NFB, and the filter characteristic of PLL which only has to respond to 19 kHz is improved.

It has a 7-station memory function.
This function is retained even if the power switch is turned off.

Equipped with a recording level calibrator for air check.

There was a rack handle sold separately.

Model Rating

Type	FM tuner
Receiving frequency	76.0 mhz to 90.0 mhz
Practical Sensitivity (75 Ω, IHF)	1.0 μ V/11.2 dBf
50 dB S/N sensitivity (75 Ω, IHF)	Mono : 1.9 μ V/16.8 dBf Stereo : 19 μ V/36.8 dBf
Harmonic distortion factor	mono: 0.1%(100Hz) 0.08%(1kHz) 0.1%(6kHz) stereo: 0.1%(100Hz) 0.1%(1kHz) 0.1%(6kHz)
Cross modulation distortion factor	mono:0.05% stereo:0.1%
Capture ratio	1.0dB
Effective selectivity	80dB
Image interference ratio	110dB
Spurious interference ratio	110dB
IM interference ratio	110dB
AM suppression ratio	65dB
Stereo separation	45dB(100Hz) 50dB(1kHz) 45dB(10kHz)
Subcarrier suppression ratio	72dB
Muting threshold level (75 ohm, IHF)	mute1: 2 μ V/17.3 dBf (mono) 2 μ V/17.3 dBf (stereo) mute2: 16 μ V/35.3 dBf (mono) 16 μ V/35.3 dBf (stereo)
Frequency characteristic	30 Hz ~ 15 kHz + 0. 3-0. 5 dB
Output signal level (400 Hz, 100% modulation)	Variable out : 0 ~ 1.5V/2.5k Ω Fixed out : 750mV/2.5k Ω DET out : 160mV/2.5k Ω Rec level : equivalent to 50% frequency modulation (333 Hz)
Antenna input impedance	75 Ω equilibrium
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law standard)	15W
External dimensions	Width 420x Height 61x Depth 348 mm
Weight	6.5kg
Sold Separately	Rack Handle BH-50 (¥ 3,500)