Before "tuning up" anything, see if the amp "works" and is being keyed properly by your rig by doing this: Connect FL-2100 output to your antenna or a kW-rated dummy load. Set FL-2100 meter switch to IP (viewed on the left hand meter). Set FL-2100 STBY/OPER to OPER (operate). Set FT-900 to SSB on any band. Do NOT modulate the rig (talk into the mike). Turn on the amp. Key the PTT on the FT-900 and watch the IP meter. It should raise to about 0.1A. This isn't critical, but it should raise to "something" and not be zero. The OPER lamp should be illuminated. Release the PTT on the FT-900. The amp should switch itself back to "bypass" automatically. You'll hear a relay in the amp switch (click) each time you press or release the PTT. If all that works okay, then you're ready to actually transmit and apply a signal and drive to it. Let me know if that all works okay.