Description.

The circuit shown here is of a TV antenna booster based on the transistor BF180. The circuit operates in the UHF band and has a gain of 15dB. Capacitors C2,C3 C4 ,C5 and inductors L3, L4 forms a UHF band pass filter. The input signal is fed to the emitter of Q1 through this filter. Resistor R2 and R3 biases the transistor Q1 which is wired in the common base configuration.

Circuit diagram.

Notes.

  • Assemble the circuit on a good quality PCB.
  • For better performance, enclose the circuit in a metal box.
  • The circuit can be powered from 12V DC.
Author

26 Comments

  1. How to check circuit with DMM if it’s working? Thanks.

  2. mnasim31

    Seetharaman jee, can I use this circuit as add-on to my UHF tv transmitter circuit in between the circuit and the antenna? Thanks

  3. okpala michael

    sir can i use BC547 to replace the transistor. tanx for the ckt

  4. where will i feed my cathode (-) from 12vdc to my circuit board

  5. Pls i want to know what is wrong wit my antenna the signal strength is very low

    • Seetharaman

      Check for corrosion in the connecting leads, Dipole edge connections at the clamp end. directors and reflector also should be clean at the clamp end. The dipole should not touch each other at the wire connecting end. You check the continuity of the antenna wire at the receiver end it should be 15 to 50 ohms depends on the length of the cable used from antenna. Do not coil the excess length of the cable anywhere. cut the excess length use only the required length of cable. Check also the direction of the antenna

  6. Pls send right up on fire alarm using thermistor

  7. please wht is the function of L1 and L2 and C7, C6, C8, C1, R1. I have to defend this in my project please.

    • did u have answer to it and did the circuit work wen u use it for ur project

  8. saya membutuhkan antena yng cocok untuk di daerah pegunungan yng sinyalnya sangat lemah sekali. tolong ksik petujuk/ jawabannya. thankyou

  9. Kasun Chaga

    Could you please send me a PCB layout of this TV booster circuit. Thank you very much.

  10. Seetharaman

    In winding inductors for RF designs, this measuring circuit allows the designer to know exactly when the desired inductance has been achieved. As an example, the number of turns for a single layer air core inductor is given by

    N =[ √l X (9a + 10b) ]/ a²

    where

    l = inductance in microhenries,

    a = coil radius in inches,

    b = coil length in inches,

    N = number of turns.

    • Pete McQuade

      How do you know what guage wire to use with this formula?

  11. Hi whow can i make those inducters as they are not aveilable in market?

  12. Seetharaman

    Hi use cable TV amplifier appeared earlier on this site

  13. Seetharaman

    Hi Howard use a low pass filter for DC and Hi Pass filter for the RF. (just a capacitor to block DC and a choke to block RF.

  14. I’d like to build manhatten-style (point-point, directly on a copper-clad board), mount it on the back of a UHF bow-tie antenna, and powered from a wall-wart at ground level. How can I separate the DC power from the RF if I use only the RG-6 feeder cable for the interface?

  15. seetharaman

    Hi Manir you can use 2N918 BF594 BF597 BF595 BF197 BF195 BF194 BF195 BF 173 BF176 any high frequency transistor can be tried

  16. Hi,

    BF180 is not available in the stores around Toronto, 2SC2570 is not either.

    What are the substitutes of BF180?

    Thanks.

    Manir

  17. seetharaman

    Hi Roger i have not yet tried with BF180 but i tried with 2SC2570 really good performance in UHF band noisey signal will improve and the grainy picture will get improved, audio mush also will come down.( you cannot use where signal strength is quite high