Working on optimizing my 432 MHz EME station and running into some discrepancies in my link budget calculations. Average loss for Earth-Moon-Earth path is 252.5dB for 144MHz, varying ±1dB monthly as range to Moon changes. Scaling this to 70cm should give me roughly 261dB path loss.

Current setup: 4x19-element array (~19dBi), 750W, 0.6dB NF preamp, but still struggling with weaker stations. For successful EME contact on 144MHz, sky noise in direction of Moon must be ≤500°K. Is galactic noise the limiting factor here?

Also seeing significant Faraday rotation at 432 MHz - full 360° rotation possible. Should I be considering circular polarization or just accepting the losses?

Your path loss calculation is close. EME signals will be weaker at apogee compared to perigee as distance is more. The 261dB figure assumes perfect conditions - add another 2-3dB for practical scenarios. Don't attempt EME when antennas point coincidentally at Moon and Sun. Galactic noise is definitely your enemy on 70cm.

Faraday rotation on 432 is brutal - more than one complete rotation possible on lower bands. Many successful 70cm EME stations use switched linear polarization (H/V) rather than going circular. Monitor your signals and flip polarity when they fade. It's more work but cheaper than rebuilding for circular.

Galactic noise especially problematic when moon crosses plane of Milky Way twice monthly. Use moon tracking software to avoid these periods. Your system should be adequate - the key is patience and scheduling with complementary stations. Consider trying Q65 instead of JT65 for the 1-3dB sensitivity improvement.