Greetings to the group:
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?? I see I will have to go back and duplicate Emanuele's measurement setup exactly; I can do that but it will take a while.
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? In the mean time, I have taken some more pictures with my network analyzer.?? Someone was wondering about how the input looked on the lowest two bands when configured as an unbalanced input.?? I can confirm that the input looks very strange.?? On the upper two bands, it looks pretty reasonable and the best match point moves around with the main tuning dial.
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Here are the screen captures:
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S-85 band 2 input
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S-85 Band 3 Input
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S-85 Band 4 Input
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If you are wondering what happened to band 1, it is so far from 50 ohms as to be effectively not there; the plot doesn't tell you much.
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Here are the responses taken from the mixer grid with the tube removed; they follow the main tuning dial reasonably accurately.
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Band 1 high, mixer grid.
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Band 1 low mixer grid
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Band 2 High Mixer grid
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Band 2 Low Mixer Grid
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Band 3 High Mixer Grid
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Band 3 low Mixer Grid
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Band 4 High mixer grid
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Band 4 low mixer grid.
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73,
--
Jim T.
KB6GM
