With only one LPF installed, it is hard to know whether the fault is 'global' for all bands, or just in the one LPF - so it is harder to know where to look.
If you measure resistance from cathode (line end) of D508 to cathode of D511, do you see a short-circuit?? You should if the toroids and diodes are soldered properly.
Also, on your LPF sweep, which you say looks ok, is the top level (left axis value) near 0dB, and the bottom near -20 or -30dB?? Sometimes the filter shape can look good, but the vertical axis scale wrong because of another fault.
Another check, if you test tx on 160 using the 'T' in the diagnostics page, what is the Transmit voltage and bias current reading, both before and after pressing 'T'? - does it just go quickly to swr protect when 'T' pressed?
Stan KC7XE
