CC-Series, Cool Stuff, Operating, VRX-1

This Is What Radio Is All About

KE7GKM QSO
KE7GKM QSO

Over the last few days, Jennifer has been off work, so I’ve been able to spend more time in the shack working on Project X. I only recently made my first QSO with the prototype rig (I think propagation was unfavorable for me when I was trying late in the evenings), so I’ve been leaving the radio hooked up to my bench AF amp and monitoring 7030 kHz during the day.

Late this afternoon, I heard a very strong station calling CQ just a bit up from 7030. I bumped the VFO up a bit and found that it was KE7GKM calling at a nice, comfortable speed for me (my CW is rusty after quite a few months off the air). While I called him back, the thought occurred to me that the call sounded familiar, but I couldn’t remember how. After getting the QSO basics out of the way, I remembered why. Bob said that he was using a VRX-1 and homebrew QRP transmitter combo! Then it hit me that Bob had just e-mailed me about a week ago to ask me a few questions regarding the VRX-1.

I don’t get on the air as much as I should (seems like I’m melting solder way more than pounding brass), but when I get a chance, it means so much to me to have a contact with someone who has built one of my radio designs. It’s even more special when I get that make that QSO with a homebrewed radio on my own end as well. If I remember correctly, this is only the second time that I’ve done such a thing.

Bob told me that he is trying to get to 100 QSOs with his VRX-1/HB TX combo, and that I was QSO #80 (if I remember correctly, my notes aren’t great). I wish Bob all the best of luck in his endeavor. It certainly looks like he doesn’t have much more to do in order to meet his goal.

It’s hard to beat an experience like this in capturing the essence of amateur radio for me. It is my hope that more amateurs will homebrew their own gear so that they can get that same thrill.

CC-Series, Design, Homebrewing

Creating PCBs with “PCB Fab-in-a-Box”

G3UUR Crystal Checker
G3UUR Crystal Checker

I decided to make my initial Project X prototype PCBs at home using the old tried-and-true method of toner transfer (via Pulsar Professional paper and foil). Since I’m a novice at PCB layout, I didn’t feel comfortable paying the money for a few proto PCBs from a board house, then finding out that I did something wrong and flushing that money down the drain. Instead of buying Pulsar’s starter kit, I just purchased a pack of the transfer paper and a roll of the green foil. I also got the required GBC laminator from Amazon instead of paying significantly more for it from Pulsar.

Last night, it was time to give the process a whirl, so I decided to make a PCB of the G3UUR crystal checker circuit that was printed in the Fall 2010 QRP Quarterly (an excellent article, by the way). The instructions seemed clear enough, but I had about five failures before I finally figured out how to make the process work correctly. I was just about ready to chuck the whole thing in the trash bin, but I managed to keep my wits and persevere through it. For those who might be new to the process, let me help you to avoid some of the problems that I had:

  • Give yourself at least 0.5 inches of copper clad clearance on each margin of the final board edge in order to give the laminator good purchase on the board and transfer paper. Putting the toner traces too close to the edge will result in those edges failing to adhere to the board. There’s just not enough heat and pressure to do the job properly at the edge.
  • When passing the copper clad plus transfer paper through the GBC laminator, I found that it worked better with four passes. Pass the board once, turn it 90°, pass it again, etc., until all four edges have been the leading edge through the laminator.
  • I didn’t see this mentioned in the instructions, but after you apply the foil on top of the toner traces, you must let everything cool down to room temperature before attempting to peel the foil off the board. Failing to do so will rip most of your toner off of the board!

Once I got the bugs worked out, I was quite happy with the end result. I also decided to try out a new etching method. Instead of using ferric chloride, I used the hydrogen peroxide/hydrochloric acid recipe that I’ve seen touted on the Internet. Let me just say that it worked out beautifully and is waaaaay cheaper than buying ferric chloride. It only took about 3 minutes to etch my small board in a Ziploc baggie. No need to mess with expensive equipment or chemicals!

The etched board turned out very well. There are a few places with very close traces, as you can see in the photo above. These etched out perfectly, no problems at all. You might notice some bad copper on the bounding rectangle on my board, but that was because of the close clearance between that trace and the board edges. I know how to avoid that in the future.

Tonight, I got the board all soldered together and it worked perfectly on first power-up! That’s always an extremely satisfying feeling. Now that I’ve got a handle on the process, I feel comfortable using it on the Project X prototype. Stay tuned for more progress on the new radio!

G3UUR Crystal Checker - Bottom
G3UUR Crystal Checker - Bottom
G3UUR Crystal Checker - Top
G3UUR Crystal Checker - Top
Uncategorized

Late November Project X Status Update

My normally scheduled time to work on the business has been cut a bit short in the last few weeks due to the various little problems in life that crop up. On top of that, I’ve been fighting one nagging problem that’s been vexing me for the last few weeks. Progress had ground to an excruciatingly slow pace and I was getting more than a bit frustrated.
The good news is that I think I finally have that nasty bug squashed and I’m back on the road to progress. The basic keyer code is pretty much done and the transmit sequencing code is also just about nailed down. Once that’s done, the last things to implement in hardware/firmware will be the frequency counter and the voltage sensor. Once that’s complete, then I can finally get some PCBs made!

CC-Series, Random Musings

In Case Anyone Cares

Here is the “Project X” proto:

Project X Prototype

It’s kinda big with thru-hole components, but the current plan is to use SMT in production. Does that sound like a good idea, or does the mere mention of surface mount turn you off?

Update

Due to “popular demand”, I’ve decided to release a bit of information on this rig. This isn’t a guarantee of final specifications, but the end product should be pretty close to this.

The rig above is a 40 meter CW superhet. Cascode JFET circuitry is used extensively throughout the radio. I’m aiming for this to be a trail-friendly radio. I don’t have any hard specs yet, but here are some general observations:

  • RX current draw is now around 30 mA, but I’d like to squeeze it down further if I can
  • TX is Class E, so TX current draw should be pretty good as well
  • Nominal TX output power is 2 W
  • MDS should be around -130 dBm (500 Hz BW)
  • VFO tuning range approximately 40-50 kHz
  • VFO stability is very good (~2 MHz VFO frequency)
  • ATmega88 microcontroller for built-in keyer, mute, frequency counter, battery status, etc.
  • Other planned bands are 80 m, 30 m, and 20 m. Would like to tweak design for upper bands as well for a future date

Hopefully that will whet your appetite a bit. Let me know in the comments any features that you would find useful that would be appropriate for a radio of this class.