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--- attenuator [2024/02/06 15:40] – ei3jdb
+++ attenuator [2024/02/06 16:16] (current) – ei3jdb
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  * R1, R3 = 50.01Ω
  * R2 = 250kΩ
@@ Line 35: / Line 36: @@
  * R1 = 50Ω resistor, power of the left-hand port (I used 450W)
  * R2 = 250kΩ resistor, about 1% of the total power (I used 2 x 3W 500kΩ in parallel)
  * R3 = 50Ω resistor, power of the right-hand port (I used 2 x 1.5W 100Ω in parallel)
  * 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)
- * Box that can sink the heat (I bent some 50mm x 3mm aluminium strip into half a box -- another piece of aluminium sheet can make a lid.)
+ * Metal box that can sink the heat (I bent some 50mm x 3mm aluminium strip into half a box -- another piece of aluminium sheet can make a lid.)
+You will also need things like a soldering iron, drills, spanners and screwdrivers to fit the connectors, and some way of measuring RF impedance.  I used a NanoVNA but any RF source coupled with a SWR meter should also work.
 ==Construction==
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 Here is my ugly soldering:-
+{{ :attenuator:soldering.jpg?400 |}}
+ * R1 is the large resistor labelled "Anaren"
+ * R2 is the pair of pale blue resistors
+ * R3 is the pair of black resistors numbered 100 0
+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.  The black resistors are 1206 form factor so they're about 6.5mm and about 3mm wide.
+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==
+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.
+{{ :attenuator:testing.jpg?400 |}}
+If these tests pass, you have an attenuator.