Hafler 9505 MF Test |
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The information presented here outlines modifications to the Hafler 9505 worked out by John Andrews, W1TAG, and myself during the summer of 2007 in anticipation of receiving the WE2XGR Part 5 license for 505 - 515 kHz. A previous write-up, Test results - Hafler 9505 For Use as an LF Amplifier provides background on the test setup and the results of harmonic and IMD spectral analysis at LF (136 - 138 kHz). | ||||||||||||||
Harmonic tests: |
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Harmonic testing at 200 watts - without low-pass filter on top and with low-pass filter on the bottom. Reference line of the plot is +60 dBm (1 kW) - the 200-watt signal registers +53 dBm. |
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Harmonic testing at 400 watts - without low-pass filter on top and with low-pass filter on the bottom. Reference line of the plot is +60 dBm (1 kW) - the 400-watt signal registers +56 dBm.
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IMD tests: |
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Two-tone IMD test at the 200-watt power level. Each tone is adjusted to 6 dB below the PEP level used in the harmonic test (+53 dBm - 6 dB = +47 dBm). IMD levels should be referenced to +53 dBm. |
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Two-tone IMD test at the 400-watt power level. Each tone is adjusted to 6 dB below the PEP level used in the harmonic test (+56 dBm - 6 dB = +50 dBm). IMD levels should be referenced to +56 dBm. |
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Additional info: |
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At MF the amplifier topped out at 500 watts, however at power levels above 400 watts the harmonic content and IMD rise quickly. Since we're investigating the 9505 as a linear amplifier the 400-watt level at MF is probably an appropriate upper limit. Overall efficiency of the 9505 was measured at a decent 42% at the 500-watt output level but drops off to about 27% at 200 watts. Each channel idles at nearly 72 watts which impacts the lower power level efficiencies. A high-power, high-efficiency class D or E amplifier would certainly be better suited for modes that don't require a linear amplifier.
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The manual for the 9505 can be found at www.w1vd.com/9505manual.pdf. |
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