DG0OPKs HOMEMADE EME PREAMPLIFIER WITH ATF-54143

my goal for this work:

After the long and good use of the MGF1302 preamplifier designed by DJ9BV in the 90th...i decided
in winter 2012 to give my preamplifier an update.

Some is written about the use of preamplifiers in past...but for EME there is the right goal to use the
"best you can buy".

So I needed a preamplifier with lowest noise availiable, stability, linearity and selectivity.
At first I decided to go on the well known PA3BIY design published in DUBUS some years
  ago but there are no PCBs availiable anymore.

Then I found on the I0JXX homepage an interesting information and also availiable PCBs.

I started an simulation and made an redesign of the preamp with some small modifications on the
input circuit and on the working point of the transistor.
The preamplifier is working stable even with open input and/or output.

UPDATE: APRIL 2012+ MAY2012
because of some detected instabilities with open cable on the input i changed the value
of L1 to  4 turns 0.75mm CUL with 4.2mm inner diameter
and I optimized the output bandpass filter to give a smaller bandwith

Here is the modified circuit. (with permission of I0JXX)



Here are my simulation results using the modified components (using ANSOFT DESIGNER SV)

S-PARAMETER SIMULATION




MEASUREMENTS OF S21, S11 and S22 after OPTIMIZATION of the BANDPASS FILTER (May2012)

S21 (GAIN) is 24.8dB @ 145MHz, 0dB @ 115MHz and 0dB @ 215MHz

S11 (INPUT RETURN LOSS) is around 6 dB @ 145 MHZ

S22 (OUTPUT RETURN LOSS) is > 20dB @ 145 MHZ


VIEW OF THE PROTOTYPE


If you need more information please write an email