...cold-sky noise measurements

...equipment setup for cold-sky/earth noise differential measurements. Shown (left to right) are the 12VDC power supply, 1296-28MHz transverter on top, VE4MA-style feedhorn with 1296 MHz pre-amp connected, GR-1236 IF meter and an IF step attenuator (February 14, 2005).

...initial configuration, pre-amp connected directly (no coaxial relay) to the feedhorn receive port (February 14, 2005).

...finding a minimum (reference) IF noise level by pointing the feedhorn toward a "cold sky " (i.e., minimum RF noise) direction (Feb 14, 2005).

Average differential IF noise levels observed between readings with the feedhorn alternately pointed toward cold sky and the (warm, noisy) ground were 5.9 dB, with a maximum differential observed of 6.0 dB. These base-line noise measurements are good initial indications that the feedhorn, pre-amp, and transverter are performing correctly.