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Post by antigua on Nov 30, 2019 0:10:54 GMT -5
From my own testing, I've confirmed that the reason the Q factor is lower is because the wax potted pickup was hot, and so the copper's resistance was higher. Once the pickup cools down, the Q factor normalizes.
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philbard
Rookie Solder Flinger
Posts: 17
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Post by philbard on Nov 30, 2019 20:31:46 GMT -5
I did let the coil cool to room temperature before doing any readings, backed up by checking to see that DCR returned to the original reading, so I wonder if Q did in fact change as potting time rose.
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Post by antigua on Dec 1, 2019 4:50:19 GMT -5
I did let the coil cool to room temperature before doing any readings, backed up by checking to see that DCR returned to the original reading, so I wonder if Q did in fact change as potting time rose. The Q factor is determined by the real / resistive portion of the impedance. Changes in L or C will move the peak frequency, but not the Q factor. If the resistance is unchanged, then the Q factor must also be unchanged.
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Post by stratotarts on Dec 1, 2019 8:28:21 GMT -5
I did let the coil cool to room temperature before doing any readings, backed up by checking to see that DCR returned to the original reading, so I wonder if Q did in fact change as potting time rose. The Q factor is determined by the real / resistive portion of the impedance. Changes in L or C will move the peak frequency, but not the Q factor. If the resistance is unchanged, then the Q factor must also be unchanged. That is true of a fixed ratio of L/C, but not a change in C, as: A higher value of C results in a lower value of Q if L remains the same.
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Post by antigua on Dec 1, 2019 13:25:57 GMT -5
The Q factor is determined by the real / resistive portion of the impedance. Changes in L or C will move the peak frequency, but not the Q factor. If the resistance is unchanged, then the Q factor must also be unchanged. That is true of a fixed ratio of L/C, but not a change in C, as: A higher value of C results in a lower value of Q if L remains the same.
Thanks I didn't realize that.
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