The Arduino can do more than create a stable, highly accurate VFO and BFO signal source with the Si5351.
The real clout of the Arduino is in the control of many functions around the ham shack. Yes it can even start the coffee in the morning.
For most of the things we build the novelty size toggle switch works well. But you must be mindful of current ratings of the switch contacts. Typically those cutie pie darlings have an AC and a separate DC rating. They are not designed to directly switch 450VDC to a tube final.
In the graphic above two MOMENTARY push button switches are used to control a 30HP motor. The switch contacts cannot directly supply power (typically 480 VAC for 30HP) to the motor but they can control the application of power to the motor.
Let us look at our circuit. The switch marked SW2 even though momentary is NC, Normally Closed. Thus, engaging that switch OPENS the circuit. The other switch, SW1 is NO, Normally Open but is also in parallel with a set of Normally Open (NO) contacts controlled by the energizing of Relay #1 (RLY1).
So the sequence is that a momentary hit of SW1 engages the Relay #1 and latches that relay around SW1 and now power can be supplied to a power contactor (read very Heavy Duty relay) which turns on the motor. It may even have a step start circuit to step the power supplied, but a subject for another time. A quick hit to SW2 opens the Latch and the motor power supply gets turned off.
So what does this have to do with ham radio. Well, fans and friends (who may not be fans) I used this circuit to control the power to a 48VDC 35 amp DC power supply for a linear amp. The 12VDC went to two Hockey Pucks (Solid State Relays) that were on the primary side of the power supply. This would be especially useful if the primary of your supply was 220VAC.
The two switches were actually not switches but simulated contacts in an Arduino sketch. Watch this You Tube.
An Arduino Mega2560 was used thus many pins and lots of program headroom. The code took care of sequencing the bringing on line of the LDMOS amp and had safety features like if you hit the emergency STOP button you are forced to wait before a restart. Just enough time to stop you from smoking that $200 RF Device. It could also sense SWR, and switch in LPF's.
But why is there not more experimentation with the Arduino as a control device? This leads me to an actual story from my past work life.
I spent most of may career in aerospace but mid career I left the industry and had one of the best jobs ever. I spent almost two years working as an outside sales engineer for a distributor of automated industrial controls. I called on companies like Campbell Soup, Budweiser, and Del Monte (someday I will share about the canned peach line at Marysville, CA). The food processing industry has a lot of automation!
Got a call from Campbell Soup in Sacramento about their can line and the "missing label" detection system. As cans go down the line a label is slapped onto the can (they prefer to call it the affixing the label process).
So, safe guards are built into the line to detect if a can is missing a label. The simplest form is two cat whisker probes set in the line so as cans go by if there is a label no complete circuit. No label and the circuit is completed and a bell goes off or a light goes on and a line person finds the can and puts it back through the labeling process.
Those "bastard industrial engineers" (a quote from the guy who called me) sped up the line for more throughput and it was so fast that the cat whiskers were missing cans and as their detection system wasn't fast enough and needed a settling time to complete the circuit.
I watched the process for about 10 minutes, a really good idea to understand the problem as that is on the path to the solution. There had to be a different solution other than the cat whiskers trying to detect a fast moving can
It was apparent that the detection and removal could not be done instantly. So a perfect detector is a no touch control using a proximity mode photo electric device -- well actually two. The first one is to signal "a naked can on the line" and the second one down the line that detects it again but next to it a pneumatic ram to punch it off the line. Two steps: detect and remove which also gave you some control of the ram action that could be timed to act in concert with the line speed.
The Campbell Soup guy had a glazed look in his eyes and then said --well maybe I could just bend the cat whiskers so they would touch more can. Well that might or might not work -- but at higher speeds it will likely fail.
The parallel here as I heard on 40M last night -- Well I would have to learn about that and it would take time.
Some things I have done with the Arduino that don't involve the Si5351. The LDMOS Amp Control, a Remote Antenna Tuner, a Remote VFO tuner, CW sender and the Blinking Morse Code Sender to put on the beam. BTW Samuel FB Morse was first an artist and then had the idea for the telegraph after learning about electromagnets.
Susan Walker Morse by SFB Morse
73's
Pete N6QW