If an upgrade of the LNA and Tuner come out, they both should have a DC voltage test point at the output. This would help in troubleshooting. Or the readings could show up in Tuner Settings instead. The minimum and typical reading should be stated. Even the maximum might be important.The reference SNR could be a 4.
The connector is through-hole and exposed on the LNA, just take a multimeter and measure from the center pin to one of the outside pins.