Radio Amateur Bob Bruniga, WB4APR, SK

Bob was a well-known fixture in the Amateur Radio community. He's best known for his creation of the APRS, the Automatic Packet Reporting System. 

The following obit is from the ARRL.

 

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APRS Developer Bob Bruninga, WB4APR (SK)

The creator of the Automatic Packet Reporting System (APRS), Bob Bruninga, WB4APR, of Glen Burnie, Maryland, died on February 7. An ARRL Life Member, Bruninga was 73. According to his daughter, Bruninga succumbed to cancer and the effects of COVID-19. Bruninga had announced his cancer diagnosis in 2020. Over the years, he readily shared his broad knowledge of and experience with APRS, among other topics in the amateur radio and electronics fields.

While best known for APRS, Bruninga was also a retired US Naval Academy (USNA) senior research engineer who had an abiding interest in alternative power sources, such as solar power. In 2018, he authored Energy Choices for the Radio Amateur, published by ARRL, which explores developing changes in the area of power and energy, and examines the choices radio amateurs and others can make regarding home solar power, heat pumps, and hybrid and electric vehicles. Bruninga drove an all-electric car and had experimented with a variety of electric-powered vehicles over the years.

APRS originated in 1982, when Bruninga wrote his first data map program that plotted the positions of US Navy ships for the Apple II platform. A couple of years later, he developed what he called the Connectionless Emergency Traffic System (CETS) on the VIC-20 and C64 platforms for digital packet communications to support an endurance race. The program was ported to the IBM PC platform in 1988, and was renamed APRS in 1992. The recognized North American APRS frequency is 144.39 MHz, and APRS is globally linked via the internet. Bruninga founded the Appalachian Trail Golden Packet (ATPG) event, which fields APRS nodes from Stone Mountain in Georgia to Mount Katahdin in Maine each July.

ARRL Contributing Editor Ward Silver, N0AX, remembered Bruninga this way: "Bob kept pushing APRS beyond its origins as a position reporting system. He developed and helped implement numerous other uses of APRS in support of what has become the 'Ham Radio of Things,' with great potential for future amateur radio applications. Bob's far-reaching vision and imagination were as good as it gets."

Bruninga mentored USNA midshipmen in building and launching amateur radio satellites and CubeSats, beginning with PCsat in 2001. PCsat was the first satellite to directly report its precise position to users via its onboard GPS module. Subsequent USNA spacecraft included PSK31 capability (HF to UHF) and other innovations.

Amateur Radio on the International Space Station (ARISS) ARRL liaison Rosalie White, K1STO, recalled that Bruninga attended many ARISS-International meetings and contributed “enormously” to ARISS APRS activities, leading a team in developing protocols and software for rapid message exchange via a packet “robot.”

White said APRS remains a key staple in the new ARISS InterOperable Radio System (IORS) that’s now on board the ISS. She added that Bruninga offered input for future NASA Lunar and Gateway opportunities in which ARISS hopes to take part.

Last year, ARRL CEO David Minster, NA2AA, on behalf of ARRL, honored Bruninga with a brick in the ARRL Diamond Club Terrace at ARRL Headquarters. ARRL sent him a letter of appreciation along with a replica of the brick.

Bruninga held a bachelor’s degree in electrical engineering from Georgia Tech (Georgia Institute of Technology) and a master’s degree in electrical engineering from the Naval Postgraduate School. Bruninga was a 20-year US Navy veteran. Dayton Hamvention® honored him in 1998 with its Technical Excellence Award.

Bruninga authored and co-authored numerous academic papers over the years, and was frequently in demand as a speaker and presenter at amateur radio gatherings.

Survivors include his wife, Elise Albert; daughter, Bethanne Bruninga-Socolar, WE4APR, and son A.J. Bruninga, WA4APR. Arrangements are pending, although his daughter said that a celebratory memorial service will be held this summer in Annapolis, Maryland.

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 Rest In Peace, Bob. You did a lot for the Amateur Radio community.

Good Gravy.........It Works!

 I got back on the Heathkit IM-5258 which was on the back burner for over a week while waiting for parts. The parts arrived while I was doing the Timebase Project, so they sat for a while.

After replacing "The Lone Photocell" and adjusting it, I was staggered to see it within the tolerance range, and almost at the target value when I turned the analyzer back on. I spent about 15 minutes adjusting it, then put a dab of sealer on the wire leads so they wouldn't bounce around, and put the cap on it. I did the same with the four photocells in the other housing, and it took a couple of hours. If you bumped one while adjusting it's neighbor, you had to go back and at least check that it didn't get moved off of it's target value. Tedious, but required.

Final tally is all of them are within the allowable range, and they're all within 5% of the target value. Getting them any closer would be an exercise in futility, so I'm going with what they are. Once the photocells were adjusted properly, the rest of the alignment/calibration went by the book.

Here it is measuring the residual distortion of my little Heathkit SG-1272 audio generator:

 It's reading about .04%, within the published specs for the generator, but others have reported this generator as being better than that. Suspecting a Ground Loop, I disconnected the oscilloscope from the "Output" jack, which lets me measure any phase shift between input and output, which I don't care about.

And here it is with the 'scope disconnected:

 It's reading about .015%, a definite improvement.

And yes, with NO input, and the input jack terminated, it reads "0.0%", meaning the needle doesn't move off zero.

Are these readings believable? Well, it's on it's most sensitive range, and the meter is barely off the zero. The rated accuracy is listed as "5% of Full Scale", so that number of ".015%" is open to some interpretation. It's literally at the limits of this instrument, but it does show *something* is there. It also shows how careful you have to be making these measurements. Everything has to be shielded, you should be running on an isolation transformer, and a little experience and luck don't hurt, either.

SO.......was it worth it? In terms of Educational Value, absolutely. Repairing this piece of test equipment and the companion Intermodulation Analyzer has helped me understand the measurements they make by understanding how the measurements are made. Understanding how a measurement is made leads to insights about what the measurement represents.

In terms of "Bang for the Buck" and usability of this instrument? A big "MEH"....There are far better instruments to use in this day and age to make these measurements with. This one is a 1970's hobbyist-grade device, made with decent quality parts from a proven design, but it sure ain't no HP instrument! Things like the knobs, switches, and controls are consumer-grade and are a bit sloppy.

This thing fought me tooth-and-nail. The chassis was bent, a rack handle was bent, the plastic coupling for the tuning shaft was broken, one of the power supply regulators had failed, The Lone Photocell had gone out-of-tolerance, and it was (and is) a beat-up, filthy mess...

Sometimes I feel like this when I finish one of these:

BUT........ it keeps me out of bars at night.

Looks like I can finally get back to my Pioneer SX-980, which started this trip down the rabbit hole......

Workshop GPS 10MHz Timebase Wrap Up....

 Gee, now that I've got the HP Z3801A "SmartClock" up and running nicely, why don't I go ahead and use it as the 10MHz Master Oscillator for all my test equipment?

So I spent this afternoon doing that. Had to move some things and string a cable from the receiver over to the antenna sitting in the window, and then plug it all together.

Here's the antenna, doing a very nice rendition of "Poor, Poor, Pitiful Me" as it's at least 20" below ground, in an East facing window, with a metal window well. I'm picking up satellites from the other side of the house when their elevation is high enough. I'm guessing it's reflections it's picking up. "It Works", but will work as-intended once I get the antenna outside and up in the air.

This is the software I'm using. It's "Lady Heather's Disciplined Oscillator Control Program", emphasis mine. The program icon is a Dominatrix with a whip, as seen in the extreme lower left corner. It does everything I wanted to do, and more, and it's a free download compared to the other paid (and crappy) software I'd been using.

 So here it all sits, an "obsolete", surplus GPS Clock, with a cast-off, rescued old laptop I was given, providing an extremely accurate, stable, 10MHz reference signal to all my test gear.

"Old" Technology can be very useful when properly applied.....

And speaking of Old Technology, the photocells for the Heathkit THD Analyzer have finally arrived, so that turkey can go back on the bench.....

HP Z3801A GPS "SmartClock" Repair

 So there I was.....

With apologies to juvat over at The Chant....

As part of the electronics shop "upgrade", I dug out my old HP "SmartClock", which is a GPS-based time and frequency standard. I've had this little box for around 20 years, and it always worked flawlessly. I originally bought it to use as high-accuracy portable clock to synchronize my laptop clock for portable satellite operation, as well as give me an accurate LAT/LON position to enter into my satellite tracking program. Kinda killed two birds with one stone. It also has a VERY good 10MHz timebase in it, which I had plans to use, but never did. These were originally made for use at cellphone towers, where accurate time was used for billing and hand-off timing between towers.

The neat thing about the 10MHz timebase is that it's not only an HP "Double Oven" oscillator, but it's also "GPS Disciplined", meaning it gets locked to the extraordinarily accurate clocks in the GPS satellites, and provides a 10MHz signal that accurate to something like one part in 10e12. Crystal oscillators are about "as good as it gets" for short-term stability, but can, and usually do, drift over time. Part of the GPS signal is a one-pulse-per-second (aka "1pps") timing hack that's ONE SECOND, by God. Well, about as good as He lets us make for now.  How the GPSDO works is explained in the link above, so I won't go into it here.

Anywhoo.....When I plugged it in some years back, none of the lights came on, so I shelved it until I could a round tuit. Opened it up the other night, and started poking around to figure out why it wasn't powering up. The supply was good, but no blinky lights. Then I noticed this:

Well there's your problem....One of the Molex contacts came loose in the housing, and slid out of position when the housing was plugged into the board.

Easy-peasy fix. Pry the tiny locking tab out a bit, snap the contact back in the housing, and reconnect.

Fixed and ready to plug back in.

The next step was finding the old software I had, and then getting it to run on Windows 7, which is still a "Work In Progress". In the meantime, I was able to connect to the clock using a terminal program, and an RS232-to-USB adapter. Two issues with older GPS units is that if the clock has been turned off for ~90 days, and/or moved a few hundred miles, it won't have a proper list of satellites to look for when it's turned back on.

This one's been off for at least 4 years, and has moved 1100 miles since it was last used. In that case, you have to tell the device to run a "Sky Survey", and collect a current almanac from a satellite ASAP. So, connecting to the clock, I sent ":gpsystem:survey once", so it would grab the first satellite in view, and get an almanac. With a GPS antenna sitting in the basement window, it was able to do this, barely, and at least get itself locked to two satellites.

So it's just sitting there now collecting data, and begging me for a better antenna, which will have to wait for Spring when I can drill another hole through the foundation (poured concrete) and snake a new cable into the basement.

And I'm still waiting for the photocells I need to finish the THD Analyzer. USPS says they cleared Denver this morning, so hopefully I'll get them tomorrow.

Have a happy and blessed Sunday!

Minor Upgrade Project Completed!

 Finally got off my duff and put all of my test equipment on the same 10MHz timebase. Years ago (at least 10) one of my friends gave me a little Video Distribution Amplifier, and I toyed with this idea, but never had enough test equipment to make it worthwhile. Then I bought an HP Z3801A GPS Receiver, which was used at cellphone sites to keep things synchronized.

And again, the little VDA sat unused. Well, I got it out the other night to see if it even worked, and it did, but two of the output connectors had low signals on them. I cleaned the connectors and nothing changed, so I'm guessing that's why my friend gave it to me. Fortunately, since I have three instruments to lock together, I was able to use the "Loop Through" port to pass the reference signal through to one instrument, and had two good ports for my other two instruments.

Not much to see....a black box on a black (dusty!) file cabinet with black cables running to and fro...

 Since all the instruments have an internal timebase, the question becomes which one to pick as a Master Timebase? The RF generator has the optional HP "High Stability" timebase, so I picked that one. I connected it to my counter, and it read between 10,000,000Hz and 9,999,999Hz, so they agreed to one part in ten million, which is pretty good. I used the Loop Through connector to drive the 8904A Multifunction Waveform Synthesizer, and the other two outputs to drive the Spectrum Analyzer and the counter.

The internal timebase in the 8904A read 9,999,685, which meets specs, but it's several hundred Hertz low. The timebase in the spectrum analyzer measured 10,000,450Hz, which also meets specs, but is a bit high. Still, 450 parts out of  TEN MILLION amounts to fly specks, but it gives me the warm and fuzzies to have all the equipment locked to the best timebase in the house.

RF generator set to 10MHz and 0.0 dBm output.

 

Spectrum Analyzer displaying the RF generator output.

Pretty close, and to get them to "exactly" agree would require sending ALL the equipment in use to a reputable Calibration Lab, and paying a whole bunch of $$$.

I consider this to be acceptable accuracy for a home shop, and I'm aware of the ambiguities in my system. The signal generator was calibrated before it shipped, as was the waveform synthesizer. Basically the differences I'm seeing is the difference between "Meets Specs", and "Dead Nuts On".

One more little thing scratched off the list....

10" Of Snow? HAH! I Laugh At You!

 Got about 10" here, as seen on my "snow gauge".

And my son and I had it all cleared in about 30 minutes. Very dry, powdery snow like the skiers love, and the Ariens could almost blow it all the way across the street.

I'm quite pleased with how well the snowblower works, and it's pretty easy on gas, too. The last time we used it I started with a full tank, and when I refueled it after we were done, it took maybe a quart of gas. It steers very easily (YAY!) and I'm getting used to the controls and how to drive it.

The Calm Before The Storm

 Been having flurries since noon, but not much is sticking....for now. The shot below was taken at 1700 local, and at approx 1800 local we had about an inch. Expected overnight snowfall is anywhere from 6~10", with another 2~4" expected tomorrow.

So for now, we're just patiently waiting.....

Tonight's project in the workshop is to make four three-foot BNC jumper cables so I can connect all my test equipment to a single timebase generator. Three of my instruments just have the standard timebase oscillator in them, but my RF signal generator has the "High Stability" option. I'll take the output of that, run it to a little 10MHz distribution amplifier, and then to each of the other instruments. This way all the readings I make are referenced to a single timebase, ensuring their accuracy is improved.

SLW is feeling much better. Minor cough today, no fever, and no other symptoms of The Plague.

Uh-Oh.....SLW has "The Coof"....

 Well, the test kits she got at the Safeway indicates she has it, had it, or has been exposed to it. Now considering she's "Double Vaxxed" (no boosters), and has been around The Public much more than I have, she probably has a greater chance of having been exposed to it than I do.

Or will being vaxxed show you as "exposed" to the virus?

I tested negative with the other kit she brought home, even though two weeks ago I  had a nasty cold, which I thought may have been The Plague, but apparently wasn't.

Or at least the "Made In China" test kit says it wasn't.

Thought I'd read something about these test kits being about as accurate as a coin-toss, but seeing as there are several different kits, I'm sure YMMV. We just received one of the free kits from the State of Colorado, and she says she can get three more kits for free.

Be very interesting to re-test myself with one of these kits, and see what it says....

We're supposed to get 2~4" of snow Tuesday night, and another 2~4" on Wednesday, so I get to warm up the Ariens again and drive it around. Seeing as it laughed at the 6" we had earlier, it'll be interesting to see how it handles 8".......

RATS!! Now I'll Never Know.....

 Well, things are the workbench were going well with the Heathkit THD Analyzer, until the other night. I'd soldered two leads onto the circuit board pads that the photocell solders to, and this allowed me keep my Ohmmeter attached while I played with the position of the cell. This let me get a feel for how the cell picks up the light from the bulb, and how to position the cell. Having the shield cap off while playing likes this makes the resistance value of the cell go all over the place from room lighting, but at least I can see how moving the cell  up/down, right/left, in/out affects the reading, and could help me find the sweet spot where the cell should be.

The reading on the meter indicates 56,000 Ohms for this cell. The target is 28,000 to 32,000 Ohms, so it's wee bit off.

I moved the bulb as much as possible, and positioned the cell every which way to get a feel for it, and no matter how much I try, I cannot get it below 42,000 Ohms. The little foil reflectors I was paying with were required to even get it down that far. Now granted, I'm assuming this thing did work at one time, so what's changed?

I pulled the bulb out to examine it more closely, which revealed nothing. And then when I was putting the bulb back in, the "padded" tweezers I was using slipped, and TWANG!, the bulb goes sailing off to Where The Wild 10mm's Live......Buh-BYE!

The offending tool: 

Yes, some colorful language was used....

The replacement bulbs I'd ordered last week came in the day after, so all was not lost. These are small bulbs:

One thing I immediately noticed after I put the "replacement" bulb in place, is that the filament is about one-third the size of the OEM bulb:

And of course, it made no difference. I've checked all the voltages in the lamp driver circuit, and they're very close to what the schematic says they should be, indicating the the current flowing through the bulb is in the correct range, meaning the brightness of the bulb is probably correct. The other identical lamp driver circuit also has voltages that match the schematic, so it looks like things are working properly.

The other side with the four photocells adjusted just fine. The target resistance was not-too-difficult to get set, and adjusting them went about how I expected it should go. This leaves the one photocell as the last thing that's suspect. Looks like I'll have to go photocell shopping.....

Had about 6" of snow on Tuesday, and the Ariens took about 20 minutes from start to finish. It fired right up, and 6" of snow just disappeared. All I had to do was walk behind it and guide it, and I had to use a higher speed to keep the maw full, as it seemed to throw the snow better the more you stuffed into it. Too bad I didn't have it the last two winters!

A Bit Of Rearranging In The Electronics Shop

 Since I've been cranking away on projects, I decided to rearrange things on the bench a bit to make it easier to use my test equipment.

I went from this mess:

To this mess:

I've been using my oscilloscope a lot on these audio projects, and this new stack also lets me integrate a new acquisition into the mix.

The newest instrument is in the second level, on the right side. It's an HP 8904A Multifunction Synthesizer. This will be used as an external modulation source for my HP 8657B RF Signal Generator, specifically for generating the FM Stereo Multiplex Composite Waveform (whew! whatta mouthful!) so I can do a complete alignment on an FM Broadcast receiver.

The old Heathkit IG-37 that I have that basically got me back to the bench Big Time is meant to do this, but I'm not really happy with how well it works. It's a 1950's design, is really touchy to get properly aligned, and has a reputation for having a high distortion level. Thew new HP will generate a very clean, very stable waveform that will modulate the RF generator. This instrument can also produce Sine, Square, Ramp, and Triangle waveforms, and will allow you to mix them, sum them, or modulate each other. It's very close to being an "Arbitrary Waveform Generator", but not as complex.

The shop/lab/dungeon is still cluttered and messy, but I'm slowly making progress on getting it organized into a proper work area. That cardboard honeycomb core door has to go, as it doesn't give me enough workspace for equipment, tools, and Unit Under Repair. I'd like to get some countertops, and make U-Shaped workbench, but I still have to come up with a frame to hold the new work surface. 

Oh, well.....It Keeps Me Out Of Bars At Night!

Kludge or Clever?.....You Decide!

 SOOO....after I unsoldered the leads connected to the photocells, as directed to in the manual, I was able to get the photoresistors for the "Reactive" side of the bridge all set to the values listed, but the "Resistive" side of the bridge was still cranky. I went through and measured all the voltages in that section of the circuit, and they're all within tolerance per the schematic. I checked the resistors in the circuit, and they all measure within tolerance of their marked value. Everything looks "AOK", and I still can't get the photoresistor close enough to the bulb for the brightness of the bulb to lower it's value to within specs. I don't know if/how much the photresistors can drift with age, but "Bulb Aging" is a definite possibility. There's a series resistor (360 Ohms for each bulb), but  I'm hesitant to lower the value, which would make the bulb brighter, and most likely shorten it's life. Hmmmm...what to do?

I was able to track down the industry part number for the bulbs used, and they're an "1869D" bulb, still available. The range in price from Nine Dollars per bulb, to Ninety Cents per bulb, depending on vendor. I bought a couple of "10 packs" from the ninety cent guy, as it turns out they use these bulbs quite a bit in various audio oscillator circuits as part of the amplitude stabilization loop, and sure enough, the same bulbs are used in one of my Heathkit Sinewave Generators. Probably a good idea to have a few spares around here...

But in the meantime, what could I do, if anything, to make what's on-the-bench get back to where it's supposed to be?

The first thing I tried was a small piece of paper behind the bulb to position it as close as I could to the photocell (yeah, I got tired of typing the whole name), and saw some improvement.

But was it the position of the bulb, or the white paper? How's about if I try and make the most of the light the bulb produces?

I cut and bent a small piece of Aluminum foil, and wedged it in, and the value of the photocell dropped to almost in range:

So for now, it looks like by changing the size and shape of the new "reflector" in there, I should be able to get this last one adjusted to be in range. And yes, I'll tack the parts down so they don't move around and affect the adjustment.

SO, dear readers, it's up to YOU! Is this a "Kludge", a "Kluge", or a "Clever"?

As long as it works, I'll leave it "AS-IS".....