2m & 70cm PREAMPS for Satellite work (ON6UG design)

Here are some hints and tips for construction of a good preamp for satellite work.

It's main characteristics are :


Download the PDF here  for detailed construction notes. the PCB is designed to fit in a GREENPAR inline box (or RS-components reference 456-201).

To check (adjust) the bandstop filter, I used a wideband noise source and observed the results.

              (Click on any picture to zoom)

 The compact inline housing with BNC in/out - it is not waterproof. I have used to power the unit with a feedthrough capacitor instead of coax.
The box conveniently opens by removing only one screw.

View on the PCB with SMD components (the BF998 is as well a SMD)

The input coil is mounted under the PCB.

The PREAMP is of wideband design. Please note that for certain applications, a narrow band design would be more desirable. Be sure that the preamp is not overloaded by nearby FM broadcast or utility VHF-signals etc

The actual performances:

  • +20 dB on 145 Mhz
  • > -40 dB on 430-440 MHz (stopband)
  • 1 dB compression point : -15dBm on input
  • S11  not very good  (SWR on input=18:1), S21 is excellent (SWR on output < 1.1) !