TranSystems 2.4 GHz Block Down-converter - Temperature Run
Most AO40 users have a TranSystems block down-converter at the feed of their receive antenna. There are two basic types, but they both have internal quartz crystal oscillators, and they all drift. I tested one of mine in my home made environmental chamber over a temperature range of 0 to +40C.
The test setup consisted of an HP 8660C synthesized signal generator feeding the TranSystems block down-converter, and the block down-converter feeding a HP 5342A microwave frequency counter. Both pieces of test equipment were phase locked to my GPS disciplined clock, and the down-converter was placed inside the environmental chamber.
The test was started at 0C after the down-converter had cold soaked and stabilized (flat line at beginning of run). I stopped briefly every ten degrees, and then waited for thermal stability at +40C before ending the test. The results were not encouraging. The down-converter drifted 471 Hz per degree C.