Homebrew Turd® RF Power Meter / SWR Meter

Select a picture for larger image.
[turd-4]

Outside case shot.  It is built into an old California Amplifier MMDS downconverter case.  You can see the 50-ohm load on the top connector.

[turd-2]

Nokia cellular phone directional coupler overview.

[turd-1]

Nokia cellular phone directional coupler closeup.

[turd-3]

Microampere meter ballistic adjustment potentiometers.

Prototype overviews / notes


[dircoup-4]

Overview of the wattmeter showing the directional coupler and the 50-ohm load.

[dircoup-3]

RF inputs to the directional coupler.  They are BNC jacks on some scrap copper PC board for support.

[dircoup-2]

Diode detector side of the directional coupler.  This particular board and diode where taken from an old brick-style cellular phone.  The little module board has all the necessary components aleady installed.

[dircoup-1]

The actual directional coupler.  Frequency response should be good from to a few GHz.  Power handling should be that of a typical cellular phone, which have power options from a few milliwatts to +6 Watts.  The coupling factor isn't known.

[dircoup-6]

Picture of the coupler hooked to a analog microampere meter.

[dircoup-5]

Internal view.  

[dircoup-7]

Another internal view.  RF input/output is by the BNC connectors on top, the switch toggle between two 50k Ohm potentiometers to select low and high power modes.

[cell-dir-1]

Directional coupler and detector diode from a Nokia cellular phone.

[cell-dir-2]

Directional coupler and detector diodes from a Toshiba cellular phone.  This one has two coupler ports for measuring power and SWR.

[cell-dir-3]

Directional coupler and detector diode from another Toshiba cellular phone.

[cell-dir-4]

Directional coupler and detector diodes from a Motorola cellular phone.  This one has two coupler ports for measuring power and SWR.