The subject of today's posting was mentioned in yesterday's blog and now you can see it 1st hand. I converted the 60M five channel radio to 40M. Here is the Proof of Life.
40M Channelized Radio
Just think with this sketch a channelized commercial radio could be modified so it is both Channel and VFO operated. There are such radios now on eBay. (Some are reasonably priced.).
The eBay radio listings are from Canadian Marconi and from Hallicrafters.
There are other possibilities like modifying a 23 channel SSB CB transceiver using this channelization approach and that could result in a very nice (and cheap) 10M rig.
There are some hidden gems in this design. Take for instance the BPF as it was a 40M BPF tuned down to 60M by the addition of two fixed caps and retuning 5 trimmers.
Back to 40 Meters involved desoldering the two caps and a trimmer retuning. About 2 minutes of work as it was designed that way initially using LT Spice. Moving it to 20 M involves desoldering two more fixed caps and a retuning of the trimmers.
Tribal Knowledge at work here and a look at the Appendix of SSDRA. Hayward often used the same inductor for his BPF's and just moved the cap values. Your Nano VNA will not tell you that directly and EMRFD does not have that Appendix. Looking at the chart in SSDRA is most helpful at the initial design stage.
I still have the LPF that needs a rework and then we can check into the Jefferson Noontime Net on 7204 kHz running QRP. Truth be known the net control is in Fresno and uses the Half Moon Bay SDR receiver site. Fresno is closer to me than the SDR site -- so in effect the rig has to cover a greater distance to be heard.
[There was mention of a 12-position switch covering more channels, but implementation involves an engineering trade-off. You would need 7 more pins (or a pin expander) to use the 12 versus 5 as many of the Nano Pins support the color TFT. Going to an LCD would free up pins or using a Mega 2560 has the additional pins needed.
A 12-channel switch arranged for 8 channels could be easily done with the existing Nano. In case you are wondering the code uses an Array and the switch position essentially calls up values in the array which is loaded into the Si5351.]
Them that know can make things go!
73's
Pete N6QW