Thursday, March 21, 2013

RPi as a WSPR Beacon with PA47

Sorry,  this did NOT work as expected, the Wsprrypi code is still being developed. The second fork of the program is available. The RF output of the of the RPi is less noisy if the DC supply is from a well filtered source.

I have previously built my Homebrew PA47 Power Amplifier for a Propeller Microprocessor Beacons (see previous selected posts). The Propeller provides 12mW to drive the PA.

The Raspberry Pi provides about the same output power via the Dan Ankers Wsprrypi program. Therefore. it was a simple mater of connecting to the correct pins on the RPi GPIO Connector to give it a try. Thanks Dan !

Here is my initial lash up, with just a Low Pass Filter (LPF).
RPi WSPR Beacon with LPF
Measure Output into 50 Ohms =  5dbm
Here is the RPi and the PA47, with input and output LPFs attached.

With the two low pass filters, the measured output is 9.4 V PP at a 50 ohm load, or 220mW, which is 23.4dbm. The Dan's WSPR program uses only about 3% of the CPU.

I have plans to modify Dan's Wsprrypi program to include other beacon modes (e.g., QRSS) similar to those that I have used with the Propeller Processor.

FYI, This my complete family of experimental PA47 Amplifiers.
My PA47 Family
Max Power - 1w, 5w and 15w

On the air, WSPR Received Reports will be added here.

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