WhitakerAudio AM/FM Stereo Tuner 2012, Assembly & User Manual

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WhitakerAudio
• Front panel switchable output (AM, FM mono, FM stereo)
• Output impedance 100 k ohms at 1 V rms
• Conservatively rated components used throughout
• Soft-start power supply to extend component life
• Over-temperature sensor to protect against component failure
• Power requirements: 117 V ac, 60 Hz, 110 W nominal.
• Physical dimensions: 19-in wide by 16-in deep by 7-in high. Note that the depth
specification does not include back panel cables.
• Weight approximately 25 lbs.
Extensive shielding is provided on the FM tuner PWB to optimize performance and prevent
parasitic oscillations.
The tuner is built using all new components, with the exception of the tuning capacitors and
RF coils. These devices are no longer manufactured and therefore must be harvested from old
sets. In all cases, the devices have been carefully restored and inspected to meet new-old-stock
performance levels.
The AM tuner is based on a classic Heathkit design. The basic circuit, originally offered for
sale in the 1960s, is designed to provide wide frequency response in order to enjoy the capabilities
of the radio stations of the day. The AM tuner is capable of flat response up to 9 kHz and with
wide-range program sources, the effect was quite similar to FM of the day. A small amount of
high frequency pre-emphasis is employed to provide additional “brilliance” to the higher
frequency sounds, thus giving the illusion of greater range than actually present.
The AM tuner is designed to provide for optimum performance when tuned to strong signals
from local stations and powerful clear channel stations located within a reasonable distance from
the receiving point. Weak signals are problematic when it comes to high fidelity listening since
the programming cannot be enjoyed for long due to the noise and interference from adjacent
stations. Therefore, sensitivity is not intended to be a key feature of the receiver, although it is
relatively high. Careful attention has been given to selectivity and 10 kHz inter-station whistle
rejection so that maximum benefit can be obtained from strong stations. An electrostatically
shielded external loop antenna is employed for improved performance in noisy locations. A built-
in rod antenna may be used for locations where strong signals are present.