attenuator
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attenuator [2024/02/06 15:48] – ei3jdb | attenuator [2024/02/06 16:16] (current) – ei3jdb | ||
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* Connectors and wire (I bought a pigtail that had a BNC at one end and an SMA at the other, and an N-type chassis mount with an SMA on the back) | * Connectors and wire (I bought a pigtail that had a BNC at one end and an SMA at the other, and an N-type chassis mount with an SMA on the back) | ||
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You will also need things like a soldering iron, drills, spanners and screwdrivers to fit the connectors, and some way of measuring RF impedance. | You will also need things like a soldering iron, drills, spanners and screwdrivers to fit the connectors, and some way of measuring RF impedance. | ||
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Here is my ugly soldering:- | Here is my ugly soldering:- | ||
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+ | * R1 is the large resistor labelled " | ||
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+ | * R2 is the pair of pale blue resistors | ||
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+ | * R3 is the pair of black resistors numbered 100 0 | ||
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+ | The black feeder is connected to the port on the left of the diagram; the copper-coloured feeder is connected to the port on the right of the diagram. | ||
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+ | Even though the soldering is ugly the wires are quite short which, as you will see below, gives good performance up to 500MHz or so. | ||
==Testing== | ==Testing== | ||
- | Test that both the inputs produce the expected SWR measurements and impedance values (my NanoVNA said 49.something ohms and a few pF of capacitance in the 70cm band.) Also test that shorting out one port does not change the impedance values of the other by very much. | + | Test that both the inputs produce the expected SWR measurements and impedance values (my NanoVNA said 49.something ohms and a few 100s of pF of capacitance in the 70cm band.) Also test that shorting out one port does not change the impedance values of the other by very much. |
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+ | If these tests pass, you have an attenuator. | ||
attenuator.1707234520.txt.gz · Last modified: 2024/02/06 15:48 by ei3jdb