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Attached are some test results for my first build of the shared LPF for [80m/60m]. These were measured on my QMX from the antenna BNC through to the PA side of C510. (T501 is disconnected). They were measured in Rx mode. All VNA cables are accounted for in calibration so the sweeps are just for the radio.

Loss in Tx mode might be different due to use of higher diode bias current.
The flat return loss in the stopband may be an indicator diode switch losses.

I remeasured the insertion loss with the LPF switching diodes operating with default transmit bias current. It's noticeably reduced. See attached sweeps. Worst-case loss on 60m now about 0.9dB for the LPF and both diode switches. 80m is about 0.6dB. I'd be interested to know if anyone has figures to compare with any of the original filters.