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Build this Universal SWR bridge

PDF Instructions in (Spanish) [849K] submitted of Jon, EA2SN







Building Instructions:

1. Inventory all Parts

2. Install all Resistors.
Note: Bend the resistor leads a sharp 90 degrees from the body

____R1,2: 51 Green-Brown-Black-Gold
Note: R3,4 controls the output of the SWR bridge.
____R3,4: 50K ohm pot (blue)

3. Install all capacitors.
Note: Bend the capacitor leads a sharp 90 degrees from the body

____C1,2,3,4: 47n yellow labeled 473

4. Install the detector Diode.
____D1,2: 1N5711 - install flush against PCB per parts markings
   DO NOT OVERHEAT WHEN SOLDERING.

5. Wind and Install the Transformers.

____T2: Wind 10/12 turns of 26 ga wire on an FT50-43 ferrite toroid.
   For 3.5 - 30 MHz, use 10 turns (more sensitive at low power)
   For 1.8 - 30 MHz, use 12 turns (less sensitive at low power)
   Wind the wire (12") on the toroid clockwise.
   Trim the wires of T1 to a half inch.
   Strip the insulation off the wires using sidecutters or sandpaper.
   Install on the PCB and trim leads from the PCB.
   Cut the complete lead from one end of the 1/2 Watt resistor

   Bend the cut lead to 7/16 inch cross section "U" shape.
   Install this lead thru T1 and solder per the picture and schematic.

____T1: Repeat as in T2

6. Connections.
Connect the bridge to a 5W RF source(in) and a dummy load(out).
Connect two mechanical meters to J1 or one meter with a SPDT switch.
Note: Meters are NOT supplied in the kit.
Apply 5 Watts and adjust R3 for a full scale reading.
Reverse the RF connections so that the dummy load is at the input.
Apply 5 Watts and adjust R4 for a full scale reading.
The SWR Meter is now ready to use for QRP only.
Designed for a maximum of 10 Watts.

Toroids, Ferrites