High Gain Prescaler
By N.S. Harisankar VU3NSH. Phone (0491) 2576102

This design is based on DS8629 Prescaler IC usable upto 200 MHz. The front-end is based on BFR91A RF Amplifier Transistor. This amplifier stage will boost very low level signals so that one can read the frequency from transceiver remotely! The total gain of the RF amplifier stage can be controlled by potentiometer P1.

While attaching this circuit with a 30 MHz frequency counter, the reading range will expand upto 200 MHz. The Prescaler IC will give an output equal to the input frequency value divided by 100. The diodes at input stage D1 & D2 will clip over-input signals. So, if the front-end is overloaded, then there is no output from the IC. The total unit is working on 5V DC and it will be provided from the regulator IC 78L05. The transistors T1 & T2 are bipolar type and it will handle upto 6GHz. It is a low noise category transistor and this will give excellent performance in the frontend. Use Epoxy PCB. All components should be fixed with minimum lead length. After assembling the PCB clean thoroughly with Isopropyl. PCB is available with the author.

Kit/IC/PCB now available from author


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