Peter, DK7IH, designed and built this Micro-20 SSB Transceiver. I believe it is about 220 cubic centimeters. One of my original shirt pocket 20M SSB transceivers was 16 cubic inches (2X2X4). But if you do the math that is 250 cubic centimeters so bigger than DK7IH's Gem.
When you look at DK7IH's documentation, you quickly get a sense of a Sardine can chock full of Sardines. Bravo Peter!
In a tip of the cap to DK7IH, Paul VK3HN, has created a design based in part on Peter's work and can be seen here. Bravo Paul!
Thus, another diminutive (pocketsize) SSB & CW Homebrew Transceiver perfect for lugging up a very small hill and yelling CQ SOTA. Thanks to the Internet we have homebrewers separated by maybe 10,000 miles sharing information and ideas.
Their work, as I can attest, was more than a single weekend effort with Manhattan squares and pine boards. Their small size creates a whole plethora of problems ranging from unwanted circuit feedback, to heat effects and finding those really small components.
But most importantly, Peter and Paul looked beyond the existing rig templates and came up with a topology that not only works very well but is really compact. The embodiment of the "Best of All Worlds". Again, from my personal experience a very tough nut to crack. These two hams are true world class homebrewers. Check out their work and pick up a few ideas to include in your projects.
In a shameless plug for my work, the smaller 16 cubic inch shirt pocket SSB transceiver has grown to 24 cubic inches to include the nifty Color TFT display and additional upgrades with a receiver RF amplifier and full band coverage.
TYGNYBNT. Don't eat your pet!
73's
Pete N6QW