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 .
