This weekend I exchanged the LNA isolation relay by a transmit-type relay with N connectors, and replaced a short cable and N-to-SMA adapters by just two N adapters. This gave me one extra dB of Sun vs. cold sky. I then swept the position of the feed very carefully, but the best I could get was 9 dB of Sun noise.
KC2TDS (Jason) and I calculated the F/D of the dish to be around 0.45, which would mean that the septum feed would be OK as-is, but the dish’s manufacturer specs state its F/D at 0.37, although with inconsistent measurements. I decided to try a scalar ring to change the feed’s beam pattern in case that would be the reason for my low Sun measurements.
I cut out an 18″ diameter x 3″ deep “Fat Daddio” cake pan to allow the feed to protrude through the center. I reinforced the two sides of the orifice with frames cut of the waterjet. Two brackets hold the scalar ring firmly against the feed.
I am limited by the geometry of the struts, but was nevertheless able to gain 2 dB of Sun noise vs. cold sky (for a total of 11 dB) with this arrangement! ON0EME now comes in at approximately 5 dB above my noise floor, making for easy copy.
I also wired the TX port all the way to the nearby shed where the PA will reside, but didn’t get to wire the RX/TX relays, so trying to transmit and receive echoes off the Moon will have to wait until next weekend.