Data Sheet

NTE851
Integrated Circuit
VHF/UHF Prescaler

Description:
The NTE851 is an integrated circuit prescaler in a 14-Lead DIP type package intended for use in TV
frequency synthesis tuning systems over an input frequency range of 90 to 1000MHz. It performs
division by 256 in he UHF mode and division by 64 in the VHF mode.

The mode of operation can be selected by means of the bandswitch and the separate UHF and VHF
input pins provided. The output is a complementary emitter-coupled stage with controlled slew rate
for harmonic suppression.

All input pins should be AC coupled to the appropriate input signal source. Because of high sensitivity, unbuffered coupling from the local oscillator is possible in most cases. In the UHF mode, which is activated by applying a high level to the bandswitch input pin, all eight divider stages are operative, resulting in division by 256. In the VHF mode, activated by a low level at the VHF input pin, two divider stages are bypassed, resulting in division by 64. As a result, approximately the same range of output frequencies are generated fo both the UHF and VHF TV bands. An internal amplifier/multiplexer provides this control while isolating both inputs and amplifying the VHF signal. In addition, hrmonic output is reduced above 40MHz by limiting output signal rise and fall times and maintaining a balanced load.

Features:
Broadband Operation: 90 to 1000MHz
High Sensitivity
Standard 5V Power Supply
Dual Mode Operation: VHF/UHF
Complementary ECL Outputs
Independent VHF & UHF Input Pins

Replaces:
ECG851

Additional Model #'s
76-NTE851
NTE851

UPC: 768249356318