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 .
