A modular Class E AM transmitter, built in small batches in the Hudson Valley. One base unit, one deck per band, and a final that switches rather than burns.
The Embassy base carries the supply, the modulator, the audio chain and the controller. Each Envoy deck carries one band and nothing else — its own Class E network, its own auto-tune, its own meters. Add bands over time; up to four decks run from one base.
A Class E final switches the device hard on and hard off, so it spends almost no time dissipating. Ninety percent of what you pay for leaves on the antenna. The other ten goes to the angels.
Every deck is designed to present the same 3.6 ohm DC load, so a single 250 kHz closed-loop modulator in the base serves all of them. Change bands and the audio chain never notices.
Each deck carries relay-switched capacitor banks and its own controller. It finds its network across the band and across real inductor tolerance, then tells the base it is ready.
Boards arrive factory-assembled where it matters — the fine-pitch SMD work is done. You fit the power parts, wind the toroids, make the harnesses, and sign the plate on the back.
A quiet pun on the amplifier class. The base dispatches; the decks are what it dispatches.
Nothing is for sale yet, and we would rather say exactly where the work stands than pretend otherwise. The stages are the ones a distillery uses, because they turn out to describe building a transmitter just as well.
The recipe. Topology, band plan, power level and the parts that decide everything downstream.
CompleteSimulation and schematic capture. Class E networks solved per band; modulator, audio chain and supply modelled and checked.
In progressFirst boards on the bench. Low wines: it works, badly, and tells you everything that is wrong with it.
AheadHeads, hearts and tails. Board revisions, and the discipline to keep only the hearts.
AheadA pilot run. The first kits go to a handful of builders who are willing to find the problems.
AheadOn-air hours. Firmware matures, faults surface, and the manual gets honest.
AheadNumbered kits, tested end to end and signed at the bench. Batch and unit number on the plate.
AheadThese are targets from the current design, not measurements from a finished machine. They will be replaced with measured numbers when there is a machine to measure.
| Output | 100 W carrier with +125 % positive peaks — about 500 W PEP. A selectable 80 W mode runs +150 %. |
|---|---|
| Bands | 160 m, 75/80 m and 40 m at launch; 20 m to follow. One deck per band, up to four decks per base. |
| Audio | 20 Hz to 10 kHz. Transmitted bandwidth adjustable from 5 to 10 kHz each side of carrier. Under 1 % THD at 95 % modulation. |
| Spurious | Harmonics better than −55 dBc. |
| Mains | 100–240 V AC, 50/60 Hz, auto-ranging, power factor corrected. No exposed mains wiring for the builder. |
| Station | T/R relay, receive antenna jack, receiver mute, PTT, and a link bus that daisy-chains the decks. |
| Format | 3U 19-inch rack chassis. Round 2.1-inch meter faces. Black wrinkle finish, etched brass plates. |
| Supplied as | Kits. The fine-pitch SMD work is done at the factory; you fit the power parts, wind the toroids, build the harnesses and sign the plate. |
Ninety percent to the antenna.
Ten to the angels.
Progress notes will go out when there is something worth reporting. The list is not open yet — the first boards have to come back first.