...initial receive performance


...initial receive measurements were made using a VE4MA-style feedhorn, no xmit/rcv relay, a WD5AGO-preamp (0.29 dB nf, 30 dB gain), a DEMI 1296/28 MHz transverter, and an IC-7800 as a 28 MHz IF receiver. Sun noise was measured to be 15 dB above background (using GR-1236 28 MHz IF meter) at 1900Z on 4/17/05 (solar flux 78) with the feedhorn at its initial position. On 4/17/05 over the time period 2000-2400Z (a 23-cm contest day), I copied 40 moon-bounce transmissions from 14 stations world wide with the feedhorn in its initial position. The cabling arrangement shown in the photo is temporary. The tracking software/hardware worked fine over the listening period providing hands-off reception (April 17, 2005).

...feedhorn-position optimization adjustments are completed. By moving the feedhorn closer to the dish by 8" from the initial position and moving the scalar ring position forward (toward the dish) by 3/8" from flush with the end of the center tube, the sun noise increased to 19 dB above background (solar flux was 77.1 during the sun noise measurement). Moon noise measured 0.4 dB above background. Scalar ring position optimization improved the sun noise level by 0.5 dB over the value that was obtained when the ring was flush with the end of the center tube. The current equipment configuration is a 50-ohm terminated xmit/receive protection relay on the receive port of the feedhorn, a W7CNK LNA preamp (0.2 dB nf, 35 dB gain), a DEMI 1296/28 MHz transverter and an IC-7800 transceiver at 28 MHz for receive, an IC-910H transceiver at 1296 MHz (10 w out) for transmit, and a DEMI sequencer for correct xmit/recv switching (April 22, 2005).

Receive Performance: After tweaking feedhorn position, rx mono-pole geometry, and eliminating some of the rx transmission line length, moon noise measures 0.7 dB above background and sun noise (solar flux = 79.3 SFU on this day...quite low) measures 19.0 dB above background noise (June 22, 2005).

Current (April 2007) EME moounbounce configuration for 23 cm at K5SO uses a VE4MA-style feedhorn, as shown in the photographs on the "Home Page" and "Using Sun Noise" page. Performance numbers for the VE4MA-style feed at K5SO are given on the "Using Sun Noise" page.