schematic of a tv(anntena) booster

[akbarza]

hi

I find the below old TV booster(antenna booster).
as it is seen there is no transistor or opamp in it and there are only some diodes, resistor, capacitor, and self and a transformer to convert 220ac to 15v ac.
I want to know how it works and how it boosts some frequencies and attenuates others.
I tried Net for the schematic of it, but I could not find its schematic.
how does it work? what is its schematic? I know the diodes make a diode bridge to convert AC to DC.
why this dc source is needed?
thanks for any explanation.

 

[FvM]

Can you show bottom side photo?

 

[Externet]

If that unit plugs to a wall adapter, chances are it is only a power supply injector and its DC travels on the coaxial cable to the antenna where the real preamplifier is located; and the RF signal travels back to that injector board you showed where the DC and RF are separated to feed the receivers input.
So, the preamplification does not happen in the pictured board but in another board at the antenna end of the coaxial.

Could be there is a power supply (adapter) plus a power injector/signal separator (image) plus a preamplifier section (at antenna) ; 3 boards/units involved and needed to operate.

 

[Externet]

Here is one schematic; which does not mean being equal yo yours : ---> https://www.homemade-circuits.com/tv-antenna-amplifier-circuit-to-boost-tv-signal-reception/
The 'dog' is where a 12V wall adapter powers the unit.

 

[akbarza]

hi

--- Updated Apr 12, 2025 ---

If that unit plugs to a wall adapter, chances are it is only a power supply injector and its DC travels on the coaxial cable to the antenna where the real preamplifier is located; and the RF signal travels back to that injector board you showed where the DC and RF are separated to feed the receivers input.
So, the preamplification does not happen in the pictured board but in another board at the antenna end of the coaxial.

Could be there is a power supply (adapter) plus a power injector/signal separator (image) plus a preamplifier section (at antenna) ; 3 boards/units involved and needed to operate.

hi ,thanks for reply.
i think there is not anything in the antenna. the antenna is only a simple antenna without any electronic element.

--- Updated Apr 12, 2025 ---

Can you show bottom side photo?

hi, i attached below the pic of background of the pcb.

 

[FvM]

It's a power supply for antenna amplifier, no active components inside, just rectifier, filter and bias T.

i think there is not anything in the antenna. the antenna is only a simple antenna without any electronic element.

If so, the power supply is just useless. Does anything change if you unplug the supply cable?