Yesterday while performing SWR sweeps tests into a known good dummy load, my QMX lost receive, now acting like there is no antenna attached when a known good antenna is connected.
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After determining the that transmit still works as expected, and with good low pass filter sweeps and bad I/q and rf sweep results I I then determined that the bias voltage at the trifiliar circuitry capacitor C406 is either 4.8 volts or nearly zero depends on the selected band, while the logical pins from the micro for band selection into IC406 look ok.
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This seems to imply that IC402 is quite wounded and will need to be replaced.
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My question are:
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1) Are there other components that I should inspect for damage given a failed IC402?
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2) what is the recommended source for these mux ICs?
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Thanks?
Greg
N1TR
Richard Hattaway