domenica 25 ottobre 2020

Chinese Very Low Cost RF Amplifier 1-1000 MHz - 2.5W


I have recently bought trough Wish an amplifier 1-1000 MHz - 2.5W .
There was no other specifications , but the cost was so low ( 12 Eu ) that I couldn't resist .
During the first preliminar tests I saw some derating with temperature , so I added a big heatsink recovered from an old PC CPU .
The setup of the measurement is in the following pictures .
Adding a 30dB 20W power attenuator at the input of the spectrum analyzer , the power measurements in dBm was translated in dBW.




With no power at the input the amplifier drive a current of about 260 mA at 15V.
First I tried the low signal gain with an input power from the tracking generator of about -20dBm  adding a 10dB attenuator at the output of the tracking generator .

The result is shown in the following picture .


The gain is very high at 100 Mhz @ 47dB , @  52dB at 1 MHz and @ 30dB at 1 GHz .
So the flatness is around 22 dB peak to peak ....
There is also a negative peak at 52 MHz probably due to some resonant element in the decoupling of the circuit .
Being specified as a power amplifier , I have then increased the level of the Tracking generator till @ 3dBm to measure the response in saturation .
The results are shown in the following pictures .



Power is in the region of : 

@ 3W at 100 MHz current about 482 mA 
@ 2W at 500 MHz current about 380 mA
More than 0.5 W at 1000 MHz current about 375 mA 

Flatness is now about 6dB peak to peak .

I have made some measurements of the output spectrum at single frequencies to have an idea of the harmonics as shown in the following pictures .



At 100 MHz everyone can recognize something quite similar to the spectrum of a square wave 


500 MHz 


 1000 MHz ( frequency at 500 MHz comes from the generator that use a doubler inside ) 


I am very happy about the results of  this device with a cost of 12 Eu .

2 commenti:

  1. Grazie Claudio .. Poi per cortesia passare il link al venditore ??
    73 da Mauro Bernardetto IK1WVQ - K1WVQ

    RispondiElimina
  2. il contenuto spettrale fa effettivamente pensare a un'onda quadra. Dato per scontato che il generatore sia sinusoidale e che il segnale applicato sia al di sotto del massimo ammissibile, e' ipotizzabile una importante non linearita' sua interna ???
    73 da Mauro Bernardetto IK1WVQ - K1WVQ

    RispondiElimina

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