Category Archives: Lab Work

Another year…

It’s been another crazy year. I have been mostly focused on my master’s degree so I haven’t been able to participate outside of the basics and taskings. With the club, I have been keeping up but just barely. The same goes for ARES. My responsibilities in the field organization continue to expand, which is good, I’m not complaining about the responsibilities I have taken on, I just haven’t had much time to enjoy them. By in large, they have been administrative taskings so I haven’t been doing much building which has taken a toll.

At the weekly breakfast, I mentioned that the hobby has been more work than fun for a while. I think that may have put a few on edge, but it is true. School is a constant and I don’t see that going away for at least another year, I will complete my second master’s in May next year. I want to pursue a Ph.D., but I will need a break after grad school. I have some public history work lined up and I am hoping I will be more participatory in radio soon.

To that end, I am poking at PicoBallooning with some of the hams in the club. I ordered up a bunch of parts and pieces to get started in this segment of the hobby. I already have a lot of skills in APRS, packet, and sensors, microcontrollers, and singboard computers so I’m not blinded by a huge learning curve, and my aviation experience doesn’t hurt either. I would like to see us develop an actual aeronautical telemetry program but we will have to see where things go.

I also want to pick up on some of the projects that got left in the dust before moving like the Beach 40 which has been on hold since November 2015! Some of my original goals for that project have shifted, and I’m not so intent on using only discreet components as I was when the project started. There will be a reevaluation and planning period before melting solder on that project but it is on my list to get back to.

Also on the list and of greater urgency is the BPQ Node documentation project. I have three nodes to build as part of the club infrastructure upgrades in the late spring/early summer, depending on how soon we will have access to the mountaintops, enclosure roofs, and towers. This one comes first, well, parallel with some of the balloon experiments.

Added to the shack tools this year is a 3D printer, an ELEGOO Neptune 2S. It has already put in considerable benefit to the radio hobby by helping me provide cases for the BPQ upgrade project and other similar projects. I am just getting my feet wet in the 3D printing hobby but so far it is a lot of fun. I have avoided CAD for circuits and 3D modeling for a long time, it’s time to go down that road.

ARES has been tasked to provide asset tracking for a couple of parades and a foot race this year. A handful of us in ARES are working on building low-cost, low, power APRS units with an eye towards expansion into WX and sensor telemetry, multitasking the equipment. This tied into the balloon hobby as well so we have a lot of crossover in participants. I also submitted a grant for CDCA for an off-the-shelf tracker solution for the parades that we can expand on based on our other experiments in telemetry.

Lots to do, but for now, it’s back to the books.

Happy Holidays

Happy Holidays from KK6GXG!

It’s been a long year. Some plans played out, others didn’t. In the end, the things that did play out were long time goals. Those that didn’t pan out where short term and are still in the mix for future completion.

On the plus side, I did manage to get a bunch of VE sessions into the schedule this year. 27 so far with one more next Saturday for a year total of 28 sessions. That makes a grand total of 46 since I started as a VE.

Another plus was finally building a crystal set. It’s one of those things lots of people build as kids and most builder hams have done them as well. I hadn’t until now. It worked out well and I could hear several stations. In the future, I plan on building different variations and working on fine tuning them.

2017 promises to be an interesting year filled with many new builds, completion of some projects, and a lot of operating.

In the meantime…

Happy Holidays to All

~Jon KK6GXG

 

Back to the radio

KK6GXG-MakingWavesTo keep domestic peace I have not been building on the Beach 40 non-stop as I might otherwise do and there is a side benefit… By taking some time away from the build I can clear out the cobwebs and refocus on the greater project to check my thinking and my work.

I still need to do testing on a few of the sections. However I have all but two sections assembled with only minor followups. I need to figure out the value of the common emitter voltage limiting resistor on the Audio Amp and I need to wined and connect the two bifilar toroids in the RF Amp.

T_R Switch
Not a literal schematic, just a rough idea

The last two sections to build are the Low Pass Filter and the T/R Switching sections. The bit that I have been burning cycles on is the T/R Switch. I want to do something that consumes the least power overall at-rest, something basic and bulletproof.

My current thinking on the T/R Switching is a pair of relays, one NO and one NC. RX on the NC and TX on the NO. This way everything is normally in the at-rest state and I only need to run one power lead from the TX momentary switch to both power leads on the relays. Since I don’t have the relays in stock I will need to go get a pair. Sounds like a trip to HSC. 🙂

Once I have the relays I will draw up a new schematic for this section and get it posted on the project page.

While not working on the Beach 40, I did do some radio stuff. I picked up some parts for stock from Jameco one day, a bag of varactor diodes, then two days later went back to pick up voltage regulators, a bag each of 5, 9, and 12 volts.

The XYL went with me to a local Radio Shack that is closing down. We picked up a bunch of zener diodes, a pair of bridge rectifiers, and some mechanical connections at 80% off. There wasn’t much left to pick through. I also found a pair of NO SPST relays which got me thinking more about the previously mentioned T/R switching circuit.

I also ordered a few bags of various op amp transistors that are frequently used in radio circuits. Purely a stock order, and I’m pleased to say the parts bins are slowly filling up and I am getting to the point I think I could actually build my next radio without going out and buying any parts. This is a good thing and I’m fairly certain my wife will agree.
Sneak Peak: I’m thinking about a Beach 20…

Also radio, not Beach 40, the beginnings of research on VFOs. I have been looking at a lot of material on VFOs without finding what I am looking for. I want something small physically, low power consumption, as close to all discrete components as possible, all readily available parts, stable, and a wide tuning range. A tall order I think.

20150603_105313
First pencil sketch, next into the lab book and beyond

A first design only slightly out of specifications is this one I worked up from a test circuit diagram from N6QWs VVC page and the NE/SA602 spec sheet. It will be my VXO-X01 build. 😉

An Experiments page has been set up to keep a log of these kinds of long-term projects. I haven’t created the page for the VFO research yet but that will be up shortly after I update the Beach 40 build page.

One other non-radio, well mostly, is the slow planned migration to Linux. I have been wanting to this for a long time but the last time I tried it wasn’t so well planned. This time I am running both Linux (Ubuntu) and Windows (8.0) side-by-side rather than one virtual. It will be a long protracted process this time but it should result in a much better transition.

That’s it for now. Trying to keep the smoke inside the parts where it belongs until next time,

73,
~Jon KK6GXG

New-To-Me Signal Generator

120 kc (kHz) to 200 mc (MHz)
120 kc (kHz) to 200 mc (MHz)

On Saturday I picked up a few things at the De Anza Electronics Flea Market. The most impressive acquisition would be the Lafayette Signal Generator for $20.

I have been needing one and I was dreading the prospect of having to build one and having a tough time without the right tools for calibrating it, so this was a great find and a steal of a value, though I didn’t know it for sure until today.

One thing I have learned about buying used electrical/electronic equipment, particularly in at a flea market, is that you have to take your time and open it up, get documentation, inspect and clean the equipment before attempting to use it, or plug it in for that matter.

20150414_075130 Sunday was opening day. I noticed right away that I would need to replace the power cord grommet as it was in two pieces. I didn’t actually get to anything else until today.

Today I inspected all of the wiring and components, looked for hot spots and anything that would indicate an over heat. Having found nothing of the sort I moved on to cleaning, which there was surprisingly little to do. I made sure the tubes were cleaned and had no fingerprints on them. Now that I have a piece of tube equipment I will need to get a tube tester. 😉

With the cleaning done it was time for the plug-in and smoke tests. No pops and and no smoke! I let everything warm up and burn in for a good twenty minutes before starting any tests.

Testing with the oscilloscope began with the AF (audio frequency) side of the generator. After the twenty minute warm up period the “approximately 400 cycles” audio tone as specified in the manual turned out to be stable at 388 cycles (Hertz). I can work with that.

“kc” is kilocycles. The term is essentially the same as the more familiar kilohertz along with “mc” megacycles being the same as megahertz. The change over in terminology occurred slowly from the mid 70s to the mid 80s. Many hams still use kc and mc. I use them interchangeably depending what I am referencing or who I’m talking with. This piece of equipment has frequency labeled on the dial as kc and mc.

20150417_152319Moving on… The generator did its first diagnostics job with a portable amplifier I have had for a very long time (the one on the right). I clipped on the amp to the audio out and it turn out the volume control on the amp is trashed from banging around in my tool bags for a couple of decades so I will need to replace the potentiometer in that this weekend.

I then moved over to the RF (radio frequency) side of the generator and clipped on the oscilloscope. The RF side is divided into 5 switchable bands. I checked each band by referencing the frequency on the dial with the frequency on the O-scope. All five bands checked out very closely to the dial. A little lead or lag here-and-there, but overall pretty close for this equipment and its age which I’m guessing is about as old as me (made in the mid/late 60s).

20150417_152206The frequency counter I purchased last year has been giving me problems. New equipment, cheap (figuratively and cost), and no manual. With the help of the new sig gen and the oscilloscope I managed to fix a couple of minor problems and figure out the modes on the counter in the process. Looks like the electronics bench is finally coming together.

Now that I can check the receivers I build I can also check the transmitters I plan on building. I can also check portions of the radios as the construction moves forward. I plan on building more of my own test equipment but it’s nice to have a reference point or two to calibrate off of.

I also did some diagnostics on the 40 meter direct conversion receiver project and updated the project page… some very interesting results, you should take a look. 🙂

A productive day I think.

73,
~Jon KK6GXG