The Twelve

twelve_romanNo, I’m not referring to the horror novel by Justin Cronin, nor do I mean the twelve days of Christmas, the twelve disciples, or the Reginald Rose film “Twelve Angry Men.” I’m not talking about the Twelve Steps of Alcoholics Anonymous, Darryl F. Zanuck’s “Twelve O’Clock High,” Shakespeare’s “Twelfth Night,” or Robert Aldrich’s “Dirty Dozen.” What I have in mind may be related obliquely to the twelve signs of the Zodiac because those represent the twelve months.

My “The Twelve” will be a year-long campaign to build a ham rig–a receiver, a transmitter, or a transceiver–each month beginning November (my birth month) 2020. I prefer not to think of this undertaking as particularly “ambitious,” “aspiring,” or “hopeful.” Perhaps “industrious” might be apt, inasmuch as I have long believed that humans are more industrious than they are intelligent.

My purposes here are manifold. One is to so fill the life of my mind with enough planning, designing, and “noodling,” that sloth, ennui, and disgust over the state of national affairs can find no roosting place. Another is to climb above the plateau I’ve rested on for some years now in order to turbocharge my knowledge and experience in the design and construction of RF electronics. In the process, I expect to become fluent in the use of the KiCad suite of design tools, Spice and other simulation packages, and the full use of my Rigol oscilloscope and other test gear. I also expect to resurrect some skills in metal work, PCB fabrication, and silk screening, to name a few atrophied faculties.

As I’ve already mentioned, some will be receivers, some transceivers, and at least one will be a stand-alone transmitter. Some will be CW, others SSB, and one will be a good ol’ AM phone. Some will be Manhattan-style construction, some will be built on home-designed and etched PC boards, some with all through-hole parts, and some with SMD components when needed. One of the receivers will be a regen, probably Charles Kitchin’s high-performance design. For reasons I can’t explain, I’ve also been hankering to build a super VXO something or other–probably for CW and maybe for a band that has a short CW segment such as 12 or 17 meters. One of the rigs will be entirely discrete components, including voltage regulation. One of the rigs will use as many ICs as possible, including regulation, audio, IF amps, PLL, etc. And lastly, one rig will use vacuum tubes as the active components.

I’ll be building one of the Twelve for 60 meters SSB. To ease what will be, by then, my overtaxed design burdens, I might just make it a BitX60, with an Si5351-based VFO/BFO, Hayward-Kopski TIA (termination-insensitive amps) IF amplifiers, and with recalculated values for the 5.5 MHz low-pass and band-pass filters. I might just use this rig to experiment with using the Si5351 and a second rotary encoder to allow for adjusting the phase of the BFO to better match that of the suppressed carrier of an incoming SSB signal. This may improve the fidelity and clarity of voice reproduction.

I’ll include a third encoder to allow for on-the-fly BFO frequency adjustments as well. Why not use a single encoder for the VFO, the BFO, and the BFO phase and just use a menu or the encoder button to step through the functions? The answer is: because I don’t want to, and I don’t need to, either. I hate multi-function controls like that. I can tolerate them when front-panel space must be conserved (as with a small field rig), but this BitX60 will stay in my shack and there will enough space for a few more knobs (for crying out loud!). I put rotary encoders on the I2C bus anyway, so I’m not “wasting” Arduino pins, either.

In November 2021, I’ll bring this break-neck and bust-ass campaign to a close with a real stretch: a QRP two-meter SSB transceiver. I’ve long been fascinated by VHF SSB, and I have in mind to use this rig mostly for mountain topping with many-element yagis. Except for some high-end all-band/all-mode commercial rigs, there’s very little out there for two-meter “weak signal” (VHF-speak for QRP) SSB. Rather than generate the USB at HF and then upconvert, I will attempt to make a phasing exciter native to two-meters and add a five-watt power amp. In addition to SSB, the rig will also operate in true CW mode (not MCW). If I’m reasonably successful with this, others might improve on what I do and build their own.

Sometime in the next few days, I’ll finalize the list of twelve rigs to build. Then will begin the intense research, design, and noodling as I bring together the information and intelligence to make all this happen. I’m not so optimistic to think I can come up with all the design details and logistics of each month’s build within that same month, so I’ll be weaving some of that in with each-month’s construction. They’ll be opportunity for doing so when I set the rig I’m working on aside (in lieu of drop-kicking it off my back deck) when I get stuck or stymied on some phase of the construction.

Of course I’ll post updates here about the steps along the way. Each post in the series will have “The Twelve” in the title. I’m also resurrecting the DIY RF YouTube channel and I’ll show some mileposts along the way. QSL?