Uncategorized – Engineering Radio

The Green Bank Telescope (GBT)

One of the nice things about taking a small vacation is that I get to do some of the things that I like to do. We went on a brief road trip to eastern West Virginia recently and that area is beautiful almost beyond description. We spent several days staying at various state parks, enjoying the hiking and history of the area.

Then there is this:

The backside of the Green Bank Telescope (GBT)

That huge thing poking up from a fairly remote valley is the Robert C. Byrd Green Bank Telescope. According to their website, it is an off-center fed steerable dish with a 100-meter diameter collecting area. The surface accuracy provides excellent sensitivity within the 290 MHz to 118 GHz operating frequency range. It has a 61-meter (200-foot) feed arm, making the entire structure 148 meters (485 feet) tall.

The dish reflector area is a 100 x 110 meter (330 x 362 foot) section of a 208-meter (682 foot) diameter symmetric paraboloid. The surface area consists of 2209 solid aluminum panels, each with its own actuator to adjust the surface and compensate for gravity, which distorts the paraboloid differently depending on the elevation angle. Maximum distortion occurs in the full horizontal (bird bath) and the maximum vertical elevations. The surface accuracy is better than 50 micrometers, allowing for efficient operation into the 118 GHz region. The total collection area is 9,300 square meters or 2.3 acres. As they say, “We could detect a cellphone in airplane mode on Saturn.”

In other words, it is large.

Your author, chatting with Mike from Troy NY about motorcycle camping

The Green Bank Observatory is located in the Nation Radio Quiet Zone which stratles the WV/VA border. The area within a 10-mile diameter of the GBT is closely monitored and regulated. Even WiFi at the nearby Green Bank public library is not available. All of the computer networks in the facility are cabled Ethernet. There are no broadcast stations and cell towers are very restricted.

One bonus for going on vacation in the National Radio Quiet Zone; no phone calls, text messages, or annoying email alerts while out enjoying the natural beauty of the area. A vacation without interruption is truly relaxing.

The Green Bank Observatory has several other radio telescopes on site researching several areas. The original Reber Radio Telescope (named after its builder, Grote Reber) is displayed by the visitors center. The Reber Telescope is considered the first radio telescope purposefully constructed and it dates from 1937.

If you are interested in science, technical stuff, or just like to go stare at giant receive dishes, I highly recommend a visit.

Consulting work

I have been doing some non-broadcast-related consulting work lately. It is actually sort of fun and pays well. One thing that I have become involved in is solar installations, or more precisely data communications from solar installations.

It seems that a critical part of any solar installation is the production numbers. Owners/investors like to see a return on investment. They like to know that their system is working properly. Getting hard data on electricity production is an important part of the customer service aspect for a solar installation company. Being able to remotely monitor the system and be alerted of any faults or failures helps keep those production numbers where they should be.

Solar installation on a large fuel storage tank:

87.5 KW Thin film solar panels installed on a fuel storage tank

It turns out that those fuel storage tank facilities use a lot of electricity. Not just for the fuel transfer pumps, some of their product is heavy oil; #4, #6, Resid or bunker oil is very thick (or viscous). Tanks, pipes, and pumps for those distillates must be heated to certain temperatures in order to move them. That is all done with electric resistance heating.

There is a very good book about oil and how it is extracted, transported, refined, and used called Oil 101 by Morgan Downey. It is an eye-opening read, to be sure.

Looking at the tops of those tanks; there is a lot of unused areas. It is a novel idea to use that area to generate power for the tank farm. The thin film solar panels come in rolls. They have an adhesive backing and are peel-and-stick. The nice part about this type of installation; the steel tanks help keep the panels slightly cooler, which boosts their production on hot summer days.

Three phase solar inverters installed on fuel storage tank

In this installation, each inverter reports to a website that logs all of the output data, as well as area temperature and percentage of sunlight. This system helps the installation company and tank owner know if there are any problems with the array. In order for that to work, the LAN needs to be set up and a communication device used to connect to the public network.

All in all, that was a fun project.

By the way, if anyone needs a solar system installed, I know a company that can do it.

The Gibson Bass Guitar

Back in the days of my early adulthood, I found myself in various situations that were neither familiar nor followed any known script. Thankfully, I seemed to manage those things without getting suckered too badly and/or causing too much trouble for myself or others. Thus, when I was living in a barracks building and one of the other guys asked me to loan him $100.00 until payday, I deferred. Lending money to anyone is fraught with danger and in 1983 or 1984, $100.00 was worth quite a bit more than it is today, especially for a junior enlisted guy like I was at the time. A few hours later, the same fellow approached with a different arrangement; I would lend him $100.00 and he in turn would give me his Bass Guitar to hold onto until he paid me back. I looked at the rather nice Gibson Grabber bass complete with road case and said okay.

Now, this guy took that $100.00 and for some reason that was never clear, stole his roommate’s car that night and went UA. He was arrested a few days later some distance away near the border to another state. He never returned to me my $100.00 and I never returned to him his guitar.

1978 Gibson Grabber Bass Guitar with original hard road case

Over the ensuing years, I have picked this instrument up and fooled around with it from time to time. I even learned how to plunk along with some easier songs like Louie Louie. It was never serious and for the last twenty or so years, it sat unused in the back of a closet. A few days ago, while cleaning up, I noticed the road case sitting there. A little bit of research reveals that it was made in 1978 at the Gibson Guitar factory in Kalamazoo, MI. As it is in good condition with the original case, appears to be worth a bit of money.

I took some time and cleaned it up. One of the pots was a little scratchy, so I cleaned it with a bit of Deoxit. I took the bridge apart and cleaned it, removed the pickguard and pickups, and cleaned those thoroughly.

Being the curious type, I started fooling around with it again. I then found a few Youtube videos on how to play bass. I watched those along with some other learning tools. I began to practice scales. This turns out to be kind of fun. I do remember how to read music, although I would need to brush up on this skill somewhat if I want to become an actual bass player. I purchased a small Fender Amp, a scale chart, and a clip-on tuner and we are off to the races. I wonder how the electric bass translates to a stand-up bass. I could forgo the Rock ‘n Roll experience completely, but if I get good enough, I’d really like to play in a Jazz band. A boy can dream…

The Sportable 3306LED02 Baseball Scoreboard

This post has nothing to do with radio engineering but is full of geeky goodness, nonetheless. My son is playing Little League again this year. This is his first year in the majors division, and I have to say, I have been thoroughly enjoying watching his games. There is, of course, one minor glitch in the matrix; the scoreboard, which occasionally looks like this:

Little League Scoreboard, missing LED segments.

Now, that is more of an annoyance than anything else. I know what inning it is and what the score is. Truth be told, most of the time the scoreboard is being run by one of the parents (read: a mom) and they can become distracted at times. Very often, the ball/strike/out count is not correct, which in turn causes the home plate umpire to angrily stare up and the scorekeeper’s window.

Anyway…

As I was saying, more of an annoyance…

Regardless, I thought to myself; jeez, I fix things, perhaps I should have a go at that sign. So I spoke to one of the Little League board members who were more than grateful for any assistance I could render.

Thus, one afternoon, after work, I got the ladder out and started poking around to see what I could learn. These signs are relatively simple. Each digit on the sign has one circuit board. Each circuit board has seven segments. Each segment has fourteen LEDs in series. There is a Toshiba ULN2803APG, which is a 16-pin darlington driver, and an LM 317 voltage regulator which is fixed with a 62-ohm resistor.

Scoreboard single digit circuit board — Scoreboard single-digit circuit board

Approximate schematic scoreboard circuit board segment

After poking around with the DVM for a while, I determined that the bad segments were due to open LEDs. I measured the working LEDs and determined that each LED was dropping about 1.7 volts. I took a board home with me and rummaged around in the parts bin until I found some orange 5MM LEDs that matched the voltage drop of the ones on the board. I confirmed my ladder-top troubleshooting findings on the workbench using the DVM in diode mode. I also noticed that the Fluke DVM had enough current to light the LED, thus making troubleshooting much easier. There were three bad circuit boards with various segments out.

A few minutes with the soldering iron and presto:

Sign repaired. I little further research and I found that an Everlight MV8104 LED (Mouser part number 638-MV8104) is a near-perfect replacement. Literally, a 23.3 cent (US) part.

In all fairness to the company that makes the scoreboard, this unit was new in 2003 or 2004. It has spent at least 11 years outside in upstate NY, which is not a tender climate. They will replace the digit circuit boards for 175.00 each, plus $25.00 shipping. My repair work used 9 LEDs ($2.10) plus about two hours of troubleshooting and repairing vs. $600.00 plus perhaps an hour to replace the boards.