January AI6YM Project Updates

This isn’t a newsletter, but I’m going to send out a brief update on current projects once a month by the 10th. Okay, it’s a newsletter.

The updates will be brief, and many will become full blog posts later. Do me a favor – keep me accountable on updates. If you don’t get something by the 10th drop me a note, I’m probably hunched over a soldering iron with no clue what day it is.

Announcing the T41 Mini

tl;dr – The T41, but smaller. Full specs will be published soon. The first units will be available at FDIM & Hamvention. Kits only $399 with fully assembled radios available too.

It’s no secret I love the T41. Fully open source, modular, all-band, all-mode transceiver with a 192kHz spectrum display? I love everything about that sentence.

There’s two things I don’t love.

• The price tag. I sold my kits at a VERY low margin, the manufacturing costs on this thing are NUTS.
• The “trunk portable” design. I just don’t have the option to operate HF at home. My rigs have to be portable.

So I’ve been quietly working on a smaller, lighter, and CHEAPER T41. It needed to keep the spectrum display, big screen, powerful processor, and of course the fantastic RF performance. I was willing to sacrifice a bit on modularity, supporting every band in one radio isn’t a strict requirement either.

The current base station design makes lots of choices that make it bigger and more expensive. Everything is a trade off. Bigger easier to solder components, core functions split over many boards, full backwards compatibility to every T41 based radio ever built. There’s nothing wrong with those design choices but they all add size, weight, and cost.

The T41 Mini isn’t backwards compatible, the surface mount components aren’t meant for hand soldering (do you really want to hand solder hundreds of SMDs?), and the design has been condensed to a smaller number of boards. It’s still modular and upgradable but a bit less so than the base station version.

I’ll lay out the details in a longer blog post soon. Suffice it to say it’s smaller, cheaper, but with the same great performance.

PicoFox Update

tl;dr – PicoFox r3 shipping soon. It’s a big improvement over r2 thanks to great feedback from this community!

Manufacturing is done, I’m waiting on delivery of enclosures before final assembly can begin. Orders are open now with shipments expected by the end of January. Look for ads in QST and other publications – and let me know what you think of them (I have ZERO marketing experience).

Since I made, and sold, 50 units of the r2 design I’ve received a LOT of feedback. That feedback went in to r3. Bigger battery, better charging circuit, more output power, adjustable output power, beautiful molded enclosure. r2 was good. r3 is GREAT.

Not everything went to plan with the r3. I may have gambled a bit and went to production without validating the final circuit. 500 boards were assembled with a power transistor and an LED backward. 500 boards were manually reworked. Improvement is not perfection.

Spurious emissions are improved from r2 but there’s still spurs created by the si5351’s dithering. At full output power those spurs are below the 10uW limit (47 CFR 97.307(e)) but they’re not 40dB down so power can’t be amplified without further improvements.

A 1-2W amplifier upgrade is planned, the spurs complicate that a bit since I’ll need to filter them out on the upgrade board. Oh well, it won’t be easy but it’s sure to be an interesting challenge. Stay tuned for an announcement on that upgrade board. I designed r3 specifically to allow future upgrades.

More details to come, I’m trying to keep it brief here.

FoxSniffer Announcement & Update

tl;dr – The FoxSniffer is a handheld RDF receiver that can determine the direction to a transmitter miles away or standing on top of it. Shipments expected to start March 1st. Full specs and pre-orders are open.

I had hoped to make this announcement a LONG time ago but it turns out that building a VHF/UHF receiver from scratch is sort of difficult.

My early design had a couple of flaws. LO leakage into the detector being the biggest issue. That was easy to fix but it was masking image rejection problems. Pushing the si5351 to UHF was also a bit more challenging. My first prototype worked well enough but unit to unit variance meant a good number of devices would not function up to 450MHz.

I’ve fixed these issues by adding more filtering, more mixing stages, and carving out a dead spot in the receive band. Originally I planned continuous receive from 100 to 450MHz. Instead I’ll cover 100-225MHz and 275-450MHz. That covers air band and all the relevant amateur bands while greatly simplifying the circuit design.

It was brought to my attention that folks also wanted the option to use the device as a receiver, not just a signal strength meter / direction finder. The new hardware design makes that possible but software for it may not be ready until after the first shipments.

Current FoxSniffer information.