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: http://www.naic.edu/~phil/obsproblems/gaintempdepend.html
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All 3 receivers show a gain variation with the temperature cycle. It ranges from .5% to 1% per degF.Figure 1 has 4 25 Mhz bands at cband. Pol A and PolB are plotted in the same color. The temperature is varying by about .7 degF while the gain changes by about .8%. This occurs in all frequency bands and both polarizations. Figure 2 plots 4 25 Mhz bands using lband narrow. There are discrete jumps that correlate with the temperature cycle (this is a separate problem.. see A1459 problems). If you undo the discrete jumps then there is a .6% gain variation per deg F. Again the variation is in all frequency bands and both polarizations. Figure 3 plots polA of lband wide with the hybrid out (pol B has a separate 100 second oscillation ..see lbw 1% oscillation). The gain variation is .5% per .5 degF. It is in all frequency bands. PolB probably has the same oscillation but it is difficult to see with its 100 sec 1% oscillation.
This problem is a common problem with multiple receivers so it is probably in the IF/LO. It is definitely something in the turret room since it correlates with the turret room temperature. It has been there for at least a year. It must be a component that is common to both polarizations. Things that come to mind are:The same cband variation had been measured back in aug2000 . The temperature dependence of lbw was measured on 12jun01 after an sband transmitter run and no gain variation with temperature was seen. The difference may be that the component that was varying had not yet reached equilibrium with the temperature that the temperature sensor was measuring. lband narrow has a smaller variation than the other two. It is more difficult to measure it because of the jumps.
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