The Neophyte is working...

...for certain values of the word "working."

Over the last few days I've been hacking away at building and Arduino based signal generator using an Si5351 clock generator board from Adafuit. In another post I'll document that ordeal, but suffice to say that the signal generator is working!

Well, the very first thing I want to try is to test the Neophyte build with the output of the generator; haven't heard anything but AM broadcast breakthough so far.

So, I fire up the receiver and boot up the signal generator, and start tuning the generator starting at 7.000 MHz. Nothing, nada, bupkis, zilch. Neither a chirp nor a burp all the way to 8 MHz. How can this be? Now I'm no further along than I was before; I can't tell if the receiver is not receiving or if the signal generator is not generating. Oh, the frustration.

I'm a fan of Bill Meara's SolderSmoke podcast, and common refrain I've heard about troubleshooting is to take a step back and some time off. So, do I take his advice? Nah! I considered it, but where's the fun in that? But still, I'm at a loss as to how to proceed...no test gear, no other receivers, no clue.

I've been spending my commute time listening to older episodes of SolderSmoke; I think I'm back at about episode 60 right now, about when he was getting ready to depart London for Rome. One element of the podcast that was much more common in earlier episodes was "the bandsweep." Bingo! There is my next step.

My signal generator uses a rotary encoder to change the output frequency at the user's desire, so I could manually tune across the entire HF band to find a tone. Ugh, are you kidding me? I'd have to do it at 10 kHz steps in order to hear the chirp as I sweep around. For the arithmetically inclined, that's about 3,000 clicks of my 18 detent encoder, or almost 200 full rotations. Not really feeling the love for that task.

Instead of doing it with the hardware, I opted to beat it with software. The code for the generator was mangled to sweep the entire band and display the sweeping frequency on the LCD screen. When I hear a chirp, I narrow the sweep range. It took about four iterations of this to pinpoint my receiver's frequency. A little zero-beating and moving the Neophyte tuning capacitor, and I've got it.

Ladies and gentleman, I've managed to construct a not-quite-60M (52M or thereabouts) receiver using the plans and parts for a 40M receiver. I will now pause for a golf clap. The little bugger ranges from 5780 kHz to 5986.3 kHz, with a nice clear sound. Not much useful there, although according to NTIA the upper portion of this range is dedicated to broadcast radio so perhaps the "breakthrough" I was experiencing  was  actually bond fide radio signals. The range ~200 kHz is narrower than I expected, but that may be due to the oscillator working at a much lower frequency than I had planned.

Either way, I'm a lot happier than I was this morning: the signal generator works and the receiver works, albeit on a very wrong frequency than I built for. Now, just what the hell did I get wrong in the oscillator circuitry? Time will tell...