About 3 AM this morning, my brain said: Hey Pete, how about doing this. The suggestion was to take the 40M Hybrid Wireless and make that into the 20M version. The brain also suggested "Plug In" networks so that I could operate on either 40 or 20 Meters without resorting to a band switch.
Plan View of the 40M Wireless
The above photo is the 40M Wireless sans any Final Output stage. Yes, a real mess that would have to be totally recreated for a new singular 20M version. For starters, this version works, and we have a good sense of the physical space required and a layout that could fit in our 12X12 space. But could this work on 20M is the question.
It was an easy test to ascertain the feasibility of such a project change and the short path was to program one of the spare ESP32 boards for 20M and dig into the junk box for a 20M Band Pass Filter Board. Boom... it worked as I copied stations on 20M and so that is a good idea worth pursuing.
This approach gets me a finished radio in a shorter time span, and we can focus on keeping much of the original 40M build, while also cleaning up this mess. In the process of doing this test I also learned a hidden (to me) feature to the JF3HZB code.
Most of the Arduino code I have previously used when it comes to the Si5351 has a line in the code to set the correction factor for the Si5351. I looked in the Si53515 correction code set for the ESP32 and somehow could never find the lines of Si5351 code. This was an annoying nit as I was not 40Hz low but 2 kHz low, for which the SDR police would have my neck.
When I set up the 20M test code I noted that the BFO was off and now we were 5 kHz low. That caused me to look at the lines of code and that is when I realized there are two lines of code that need a numerical value for offset correction and the second was the carrier frequency. In the original GitHub download these were the same frequency.
Then I said let's fix the BFO frequency and a few trial runs fixed that issue. But we were not on the correct frequency on the dial. A few more runs of adjusting the frequency correction factor and that was now fixed. I even tested the code across the band, and it was correct.
I am guessing here but suspect that the JF3HZB Si5351 correction is being done in another manner by using a specific modified BFO frequency and a separate numeric dial correction factor. All roads lead to Rome!
The 20M Code
I am glad my brain awoke me as now the task is not a mountain to climb but a large hill. A follow-on test is to build the Transmit 20M BPF and add in a 20M LPF. These two small changes would give me a 20M transceiver and that will seal the deal for this approach.
Gavin Newsome sent me an email to sign a letter he has drafted regarding some sort of political action in California. I would not sign such a letter, and it has nothing to do with whether it has my support.
But in today's political environment that signature will become a part of a list of names to be investigated by the IRS and DHS as a part of Make America (you know). Any opposition to what is his name agenda brands you as anti-American. Shades of Joe McCarthy. We are indeed here at that point in the USA and freedom of speech is gone! Reduce your digital footprint.
Them that know can make things go.
73's
Pete N6QW