- Ramsey VHF Low Noise Preamp Kit Assembly and Instruction Manual

PR100 y 10
ALIGNMENT:
Alignment is fairly simple if you follow these guidelines. The first step is to
back all of the lugs out of L3, L4, and L5 until they reach the top of the cans.
FL1 should be ok, and won’t need any adjusting.
1. Screw L3 in 8 turns.
2. Screw L4 in 8 turns.
3. Screw L5 in 8 turns.
If you have the equipment and the know-how, you can adjust the coils and
the helical filter further. You will need a spectrum analyzer and a frequency
generator to run at 145.52 MHz for best alignment.
Set the generator to 145.52 Mhz and tune the coils to get the greatest
amplitude and the best shape. Check the width of the bandpass to make
sure it is centered on 145.52 MHz, and is about 2.8 MHz wide. Sweep
through to check the shape of the bandpass, it should be close to flat across
the bandpass, if not you will need to tune the helical filter.