Summer Etherkit Update
A news smorgasbord
It’s hard to believe that we’re well into July already. Things have been going well with my new job so far. In fact, I’ve been working at it a bit more than I expected at first. Which isn’t a bad thing, except it takes away from the time I have for Etherkit and Project Yamhill. It has been relatively quiet soon, but I have been working on a fair number of things in the background and it should become more apparent very soon.
Project Yamhill PCB Tranche #2
The biggest news by far is that I finally was able to submit my large PCB order for manufacturing. It was put off a lot longer than I was hoping for, because I kept finding small changes that I needed to make. However, I didn’t want to fall into the trap of analysis paralysis, so I had to commit to getting it pushed to manufacturing in order to not completely lose momentum.
As you can see, I’ve got a lot of stuff to test when I get the boards here in a few weeks. This will keep me busy the remaining summer months. I’ll probably work on the Front Panel PCB first, since that’s the one with the most (and most critical changes). I’m fairly confident the rest of the boards will be fine.
You may also notice a familiar face in that shopping cart…
The Return of the Si53551A Breakout Board?
I’ve had a good number of PCBs professionally manufactured now, and I’m fairly comfortable with the process. However, one thing I’ve never done is to have professional PCB SMT assembly. It recently occurred to me that with the advent of all of the integration of KiCad with my current preferred board house (JLCPCB), that it probably wouldn’t be that difficult for me to learn how to create the outputs so that I can submit a simple PCB for assembly.
A perfect choice for this type of experiment would be my venerable Si5351A Breakout Board. It’s been a few years since I’ve been able to offer it for sale. When I was selling it, I was spending a ridiculous amount of time hand-picking the SMT components at home. I don’t ever want to do that again for a product that I sell, so if I want to get back into this game, I’m going to have to learn how this process works.
I decided to do a new board spin in order to tweak things a little to make for a streamlined product pipeline. Instead of having multiple different reference clocks available (crystal or TCXO), I redesigned it so that it will only take a TCXO. Since that’s what most people ordered when I had them for sale, it makes the most sense.
When I get the manufactured boards back from China, I intend to set up my old testing line for the board and run the prototypes through the process. If they pass the checks, there’s a good chance I’m going to start offering them for sale, so if that interests you, stay tuned for more details.
MAX268x Experimental Direct Conversion Receiver
As I previously mentioned, I’ve been doing a bit more qualitative testing of the MAX2681 mixer IC as the product detector in a simple direct conversion receiver. The block diagram for this receiver is very simple:
Ant -> DTC -> MAX2681 -> NE5532 AF Amp -> Phones
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Si5351A OscBelow is a video shot earlier this evening, 11 July 2024 at around 6 PM local time, of me scanning the 20 meter band with this receiver. Please excuse the audio clipping in a few spots in this video. There’s no AGC in this simple receiver, for all of the good and bad that brings. Also, the noise level is kind of high thanks to my boys’ LED strip lighting in their room, but you can still hear a decent amount of fidelity. Listen as I tune from the bottom of the 20 meter CW band, up past the very loud FT8 frequencies, over some RTTY, up to a few sideband conversations, and then back down to the CW portion of the band again.
I think this will work as a substitute for the SA612. I plan to try to make some kind of simple transceiver in the same class as a Rockmite, hopefully as an eventual product to sell. I also would like to try to make a simple superhet with it once the simple DC transceiver is well into development. I think this will be fun to work with!
MAX268x Mixer Module
Speaking of the MAX2681, I also created a Project Yamhill module for it. The circuit fits quite well within the 50 mm x 50 mm footprint of the standard module. The only thing I’d like to note about this module is that the input is narrow-band, with a tuned L-network on the RF input pin. So as it stands, this module will only be good for one band at a time. I may try to come up with a wideband matching solution, but that may take a bit more work and effort from me to find a good way to match the highly capacitive input across a wide range of HF frequencies.
What’s Next
While I’m waiting for all of my boards to be manufactured and shipped here, I’m going to be shifting gears a bit back into firmware/software mode. I’m going to make a good crack at refactoring the EtherKeyer Mini firmware for size so that I can get a few more features in there. In practice this means that I’ll probably also be refactoring the Etherkit Arduino Morse library as well, since that’s what I used for message playback. I really want to be able to start beta testing (and then selling) both EtherKeyer Mini and Party Line 80 very soon now. I’m eager to get those projects in a state where I can move on to getting Project Yamhill in a state where I can have others start building it and working with it.
After this, you’ll be seeing a lot more about Project Yamhill hardware, and then hopefully a bit more about some MAX268x radio projects.