50W QRP Amplifier – PCB Layout Video

This past weekend, I started on the process of laying out the 50W QRP Amplifier project as a PCB. Small PCBs can be remarkably inexpensive these days – $10-$15 for 5 pieces of say 4″x4″, shipped in 2-3 weeks. I’m treating this amplifier project as a chance to experiment with different, similar FETs to learn about critical power MOSFET properties, and also as an opportunity to brush up my layout skills that I haven’t used in awhile.

As the first step of PCB design, I captured the schematic of the amplifier as built in AutoDesk Eagle. I did this on a livestream on YouTube, the first time I’ve tried such a thing. It was great fun! Kenneth W6KWF stopped by to lend advice – he deals with prototype PCBs as part of his day job, though he has team members to do most of the actual layouts when needed. We’ve had a great deal of fun over the years, including building a cloud chamber for seeing charged ions in high school.

Here’s the full (2h45m!) livestream in all its glory! There’s a recap and full-circuit overview at 2h41m for those who want to see the final circuit.

Hear you on the air!

73

This post is cross-posted to my more general-purpose nerdery blog, jeff.glass/blog.

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BITX40 Module & ARRL SSB Sweepstakes 2016

A few weeks ago, I participated in the ARRL Fall Sweepstakes SSB Contest, and succeeded in making my first voice contacts from home. It’s incredible what you can do with 5 Watts and a simple antenna!

Over the course of about an hour on Saturday night and another hour after work on Sunday, I made fourteen total contacts all across the US, including Colorado, Illinois, Kentucky, Manitoba Canada, Maryland/DC, Michigan, Minnesota, New Jersey, New York, Ohio, Ontario Canada, Texas, and Virginia. Several stations clearly had to reach way down into the muck to pull me out of the noise, which was very much appreciated.

Part of the exchange for the SSB Sweepstakes is a “precedence,” which is based on your power level, among other things. I was handing out “Q’s,” which denotes a QRP power level of 5W or less. A couple stations, after a minute or more of trying to pull me out of the noise and finally getting it, “OH, QRP, that explains it…”

I worked the entirety of  my contest activity through a new rig in my shack, one of the new BIX40 modules out of India. Afshar Farhan, originator of the BITX Transceiver, has recently rallied together some resources to start producing a “kit” version of that radio for the 40m band. I say kit only lightly, since the main board (which is mostly SMD components) comes fully assembled and tested, and you merely need to solder on the provided external controls (tuning and volume pots, speaker/headphone connectors, etc.) It only took about 20 minutes from unboxing the package to having everything installed. But there was an issue lurking on the horizon…


I’ll save that story for another post though. Hear you on the air!