N6EX Exciter Performance

Prior to integrating the modified exciter with the rest of the system, the unit was aligned per the TK-931 service manual. The following items were checked/aligned:

Notable Exciter Measurements

Current Consumption

Power Output

Wideband Spurious and Harmonic Rejection

Wideband Exciter Plots
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Spectrum analyzer plot showing the rejection levels of the half-harmonic and second harmonic. Observations after this plot was taken indicate that the analyzer may have been somewhat overloaded during this measurement, leading to higher indications of spurious responses than actual. Spurious and harmonic rejection of the TK-931 is specified as 65 dB minimum. Future measurements will be performed and the plot updated.

Narrowband Spurious Rejection

Narrowband Exciter Plots
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Spectrum analyzer plot showing close-in synthesizer spurious responses.

Close-In Spectrum and Frequency Accuracy

Close-In  Plot
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Analyzer plot showing the close-in spectrum with only the DPL modulation. This plot also shows a transmit frequency setting of approximately 250 Hz above the 927.1375 center frequency. The yellow trace is an instantaneous plot while the green trace is a maximum hold plot.

Transmit Audio Frequency Characteristics

Exciter Audio Plot
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Audio response of the exciter closely follows the standard 6 dB per octave pre-emphasis curve.

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