Having intermittent noise spikes with my RTL-SDR Blog V4 when using the built-in bias tee to power an external LNA on HF bands. The bias tee is enabled on GPIO PIN 0 but I'm getting broadband hash that comes and goes. Anyone else experienced this?

Setup: RTL-SDR V4 -> Ham It Up upconverter -> Nooelec LNA4ALL -> random wire antenna. The V4 is based on the R828D and has a built-in upconverter so I may have redundant upconversion happening.

Using SDR# with 2.4MHz bandwidth and standard gain settings. Should I disable the internal upconverter when using external upconverter? Any specific bias voltage specs I should check?

Check your power supply first - I had similar issues that turned out to be a noisy USB hub. Also try different sample rates, some dongles work better at 2.4MHz versus 2.75MHz. The V4's internal upconverter might be conflicting with your Ham It Up.

You definitely have redundant upconversion there. My RTL with upconverter is semi-permanently attached to my HF rig and I run it as a bandscope without issues. Try bypassing either the internal or external upconverter.

Had the same problem last month. Solution was reducing the LNA gain and running a homemade AM broadcast blocking filter to eliminate intermodulation. Those V4s have very broadband front ends that can get overwhelmed by strong local signals.