ADVANCED DESIGN FM FRONT-END
FM signals picked up by the antenna tuned and amplified by the RF amplifier, then mixed with the local oscillator signal in the converter circuit to from a 10,7 MHz intermediate frequency (IF) signal. This ciruitry constitutes what is known as the front-end, which plays a vital role in determining a tuner's value. This section must be able to amplify weak signals well, handle strong signals without distorting, and have the capability to remove completely all radio frequency noise and interference.The T-100 meets these requirements well by utilizing a linear frequency, 5-gang tuning capacitor, double tuned RF amplifier stages, complete intercircuit shielding, local oscillator buffer circuit, and dual gate FET's in all RF and converter circuits, etc. This is attested by performance ratings for spurious signal rejection of better than 100dB. Image rejection is also better than 90 dB. The T-100 also has a 245mm wide, slide-rule type dial which has linear frequency indications at 250 kHz intervals that is combined with precision tunning mechanism to ensuree smooth, accurate tuning.
15-STAGE LINEAR PHASE FILTER IN FMIF CIRCUIT
The 10,7 MHz IF signal from the front-end enters the IF amplifier circuit where it is amplified and fed to teh detector while adjacent frequency signals are rejected. This rejection(IF sensitivity) is normally the function of transformers or mechanical filters in conventional tuners. The T-100 however employs a newly developed 15 stage LinearPhase Filter combined with an integrated circuit to obtain better rejectionand, at the same time,less distortion. Thus, selectivity was made compatible with sound quality, as attested to by the performance ratings for distortion of less than 0,1% and effective selectivity of more than 70 dB, which significantly surpass the limitations of past tuners.
WIDEBAND FM DETECTOR
In order to demodulate the linear phase amplified IF signal without distortion into an audio signal, the former isfed to a special detector circuit which employs a 1,200 kHz wide discriminator which has three times the width of those normally used. This has contributrd to significant improvement in stereo characteristics.