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August 10th, 2024. Mapping the Arduino Control System

Just recently appearing on Prime Video is a classic John Wayne movie called The High and the Mighty. The movie takes place in the Mid-1950's and chronicles a commercial airplane flight from the Territory of Hawaii* to San Francisco on a Douglas DC-4. Having worked for Douglas Aircraft in commercial aerospace some things jumped out at me.




During the grueling 12-hour flight, some sort of mechanical problem develops, and Wayne is dispatched to the tail section to observe the mechanical flight control system. It was all wire cables and pulleys! 

Instant flash thought passed through my mind, it was of N2CQR and his LC VFO's (wire cables and pulleys) and today where it is all "fly by wire" and N6QW with the Si5351.

That leads us to the Arduino and the Si5351 for our CW transmitter. Luckily, I have a template of how to do this based on my 40M MMIC CW transceiver. See the June 8, 2024, posting.

The trick is to convert the discrete approach of the 40M MMIC rig over to the Arduino. Thus, I have started to think of features that will be needed for CW using the Arduino/Si5351 to generate and transmit the CW.

40M MMIC Circuit


Firstly, is that CLK0 will be the LO source for the receiver and is dependent on the rx1 which is the generated LO signal without a BFO since it is a DCR. CLK2 will supply the LO signal to the Transmitter and is 600 Hz lower in frequency (our offset). Thus CLK2 = f (rx1 - 600). The enable command will cause CLK2 to happen.

For the transition to transmit we need to detect a contact closure at the Arduino as that will start the chain of many events. We have to also think of tasks like powering on the Driver/Buffer stage. Providing a keying Mechanism, Biasing on the IRF510 and Muting the Receiver. 

The TR switchover can use the same diode biasing trick to steer the Antenna between the DCR and the Transmitter. Likely there are more tasks to add to this list.



TYBNYGNT

73's
Pete N6QW

* Of note the passengers in the movie had to check with immigration before getting on the plane and had to disclose their age and where they were born. Hawaii was not a state at the time the movie was made. There was no TSA screening process as one passenger managed to sneak a gun aboard the flight.

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