Supplying Power to an Antenna Amplifier

Discussion in 'The Projects Forum' started by PoRo, Mar 13, 2015.

  1. PoRo

    Thread Starter New Member

    Mar 13, 2015
    I am about to build an OUTDOOR antenna amplifier. The amplifier will be screwed to the OUTDOOR antenna, but its power supply will be located INSIDE the house next to TV receiver. I'd like to use ONLY TWO wires to connect the amplifier to the indoor power supply and the TV.

    Do you think the circuit below will work?


    I use L1 and L2 (two big inductors) to prevent the high frequency signal being lost in the positive line. Those inductors are so big that they appear as a broken wire to the signal. On the contrary, the capacitors C3 and C4 appear as a short wire to the signal.

    Do you think that the amplified signal will reach the TV receiver?

    Thanks for your help.

  2. #12


    Nov 30, 2010
    This is the standard way to do it, but not by an amateur. The megahertz involved are above the skill level of most people. You can buy an antenna amplifier that works this way, and it actually works.
  3. Papabravo


    Feb 24, 2006
    Without component values it is hard to draw any conclusions. The transistor you use could make a huge difference. How do you know that it provides any gain at the frequencies of interest and how is the circuit implemented? Manhattan style dead bugs, breadboard, PC board with microstripline what??

    I don't see that you have matched the source or the receiver to the characteristic impedance of the cable.
  4. crutschow


    Mar 14, 2008
    An inductor (choke) doesn't have to be that big to block TV and FM RF frequencies.
  5. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Notice that L1 as shown in the original schematic would degenerate the amplifier gain.
    @#12 are you sure your attached schematic is a valid modification?
  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
    In the original post, every single component value matters; without them, nothing definitive can be said. And the frequency band you are trying to amplify *really* matters. But without that information, there still is one thing needed. To the left of L1, the L1-R1-R3 node needs to be decoupled to GND with two capacitors in parallel, a 10 uF electrolytic and a .01 uF ceramic.

  7. #12


    Nov 30, 2010
    My only intent was to clarify that one inductor was not necessary. I wasn't being real accurate because I sincerely doubt that any normal person could build an amplifier this sophisticated, so it will probably end up as a retail purchase.

    and yes, C3 into a battery is an obvious mistake.

    Specifically, I was trying to move the power supply to the left of the TV receiver. I didn't even think about reconfiguring the collector section of the amplifier because that part will not concern a person buying a retail product.

    Sorry about the sloppiness. :oops:
    Last edited: Mar 13, 2015
  8. debe

    Well-Known Member

    Sep 21, 2010
    This is a typical Mast Head TV amp power supply from a kit I built some years ago. MAST HEAD POWER SUPPLY.jpg
    #12 likes this.