I have received a few comments and off line inquiries about my well being and the status of the Engineering Radio blog in general. First, let me say; thank you for your concern. There are many things going on right now, both professionally and personally. Some of those things are good and some are bad. In other words; typical life stuff.
First, from the professional side: The company (?) I work for has undergone some internal changes. We are, in general, very busy and I myself have at least five or six irons in the fire when it comes to projects. These include things like two complete studio projects, a couple of transmitter site rebuilds, some STL installation work, a couple of new IP data links, etc. On top of this there are, of course, maintenance issues and emergency calls, irate general managers, frugal owners, old equipment, and so on. We have had a pretty good cold snap over the last weekend (-10 to -15F), which has lead to numerous failures; pipes freezing, diesel fuel gelling, UPSs quitting, etc. <s>All in, it has been so much fun I cannot believe I actually get paid do to this </s>. If you have worked in the business for a while, none of this should surprise you.
When I get time, I will put together some posts on the above projects, as some of them are quite interesting or at least somewhat entertaining.
Secondly, from the personal side: Youth hockey season is here and I have been carting my son around to practices and various hockey games in upstate NY and western Massachusetts. Last weekend, his team played in the Empire State Winter Games in Lake Placid, New York.
End of game hand shake, USA rink, Lake Placid, NY
For any fan of Hockey, a trip to the Herb Brooks Arena can be a semi-religious experience.
In addition to this, another common radio engineering problem has occurred; marital discord. So much so that alternate living arrangements have been considered.
Thus, my time and very often my mood has been constrained. Hopefully, after youth Hockey season ends in next month, I will at least have more time to do some quality posting. Your patience is appreciated.
Political Warning! Turn away now if you wish to remain blissfuly ignorent.
На сей раз Путин прав.
Who do you think you’re foolin’ with?
For those of you who don’t govoroo pa Rooski (speak in Russian), it says: Na sey raz Putin prav.
What, specifically, is he right about? Syria: Who caused it, the resulting humanitarian crisis, the refugees in Europe, and so on. Also, the question: What is the difference between a moderate rebel and an immoderate one? Well… Starting with the 2003 invasion of Iraq, the US involvement in the region has been either grossly incompetent or blatantly evil or perhaps a combination of the two. Remember the humanitarian bombs in Libya? The opening salvo of 138 tomahawk missiles ($1.2M each)? To be sure, Muammar Gaddafi was no saint, but compared to the people who are running Libya now, he was Ma Teresa.
The US has spent approximately $500M training these “moderate rebels,” but according to the CENTCOM commander, number only “four or five.” They are just pissing away money and our kids are going to have to pay it back. When will somebody stand up and ask: What the hell is going on around here?
By the way; Путин не мой герой, which makes it even sadder still.
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.
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 was 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, a LM 317 voltage regulator which is fixed with a 62 ohm resistor.
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 LED’s 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 work bench 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.
Scoreboard LED voltage drop
Scoreboard individual LED testing good
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 troubleshooting and repairing vs. $600.00 plus perhaps an hour to replace the boards.
After replacing a burned out FM antenna for one of our clients, the question became; what do we do with the old antenna? There were several options:
- Throw it behind the transmitter building and let weeds and poison ivy grow over it
- Take it to the scrap yard to get what ever money we could for it
- Give it away to somebody
- Turn it into a fountain
I have scrapped these old antennas before, they are made mostly of hard yellow brass, which does not net too much at the scrap yard. In fact, by the time I finished removing the Radomes and separating the metal, I had more time into the job than it was worth for both myself and the client. Therefore, I present to you the ERI LPX lawn fountain:
ERI LPX2E Rototiller FM antenna used as a fountain
Upon completion, my wife and daughter, who are natural born skeptics, even had kind words to say. It seemed like a simple project at first; enlarge the dry well for the basement sump pumps and install some type of mounting base for the old antenna. It turned into a little more than that.
Mounting base for ERI antenna fountain
It took several hours of backbreaking labor, a concrete form and a few bags of ready mix concrete to create the mounting base. Several wheelbarrow loads of gravel, some rocks from the old wall in the woods and a pond pump from the hardware store round out the installation.
ERI LPX2E Rototiller FM antenna fountain
I am not sure what else to say.
Hockey is about the only sport I care about these days. The Olympic hockey rivalry between US and Russia has been epic ever since the Lake Placid games in 1980. Why then, does NBC not broadcast the game live? In order to see the game live, one has to subscribe to NBCsn, which is in the premium tier on my cable system. No, they would rather force people to pay lots of money because they can. Such if life in the land of Monopoly.
Well, for every problem, there is a solution. Mine involved a VPN connection to somebody else’s network. I watched the game, but the commentary was in Russian. I didn’t understand most of it, however, as to the results of the game; I got the general feeling that the Russians were not amused:
Not time (for/to) smile
It seems the referees made a few controversial calls, including denying a Russian goal because the US net was out of place. I wonder how that will be mentioned on the repackaged replay.
There were other streaming options as well, one just needs to hunt around to find things.
In the information age, it seems the establishment’s control of the narrative is slipping away. I view this as a positive development.
Not related to radio, but interesting nonetheless. Mozilla, the designer of the Firefox web browser has come up with a cool way to see tracking data for any HTTP sessions. It is an add-on called Lightbeam. I tried a little experiment, after installing lightbeam, I surfed around a little bit then looked at the results. A screenshot of the graphical output is below:
Mozilla Lightbeam graphical output
The round circles are the sites that I visited. The triangles are third party sites connected to the visited site. During the real Lightbeam session, a mouse over the icon will show the name or url. It is an interesting exercise. Visiting 27 web sites nets a total of 172 third party sites or approximately 6 third party sites per visited site. Commercial news sites like CNN and NBC seem to have the most connections to third party sites. In this case, it appears to be mostly innocuous advertizing. Even so, it is an enlightening experiment.
4CX250B ceramic vacuum tube
It’s a cute little thing. These were often used for driver tubes in FM broadcast transmitters. With the naming conventions of ceramic tubes, we can tell quite a bit about the unit without even looking at the data sheet.
- The first number is indicates the number of grids in the tube, 3 makes it a triode, 4 tetrote and 5 pentode.
- The C means it is a ceramic tube
- The X indicates it is air cooled, a V is vapor cooled, W is water cooled, M is multiphase
- The 250 is the plate dissipation is watts
- B is the design revision.
Thus a 4CV100,000 is a vapor cooled tube capable of dissipating 100,000 watts, something one might find in a high powered MF or HF transmitter.
Other bits of critical information about tubes would be maximum plate voltage, maximum screen voltage, maximum grid voltage, maximum screen dissipation, maximum grid dissipation and filament voltage. Something to keep in mind when tuning a transmitter.
This particular tube is installed in the driver section of a Continental 816R2 transmitter.
Continental 816R2 driver section
I have noticed that these tubes have a much shorter life than there predecessors. Back ten or twenty years ago, they usually lasted 12-14 months. The latest set lasted only 8 months and both units failed catastrophically. That points to one of two things; either something in the transmitter has changed or something in the way the tubes are manufactured has changed. Once the new tubes were installed, I checked all of the parameters against previous maintenance logs. I also checked things like air flow, dirt and other possible culprits.
I could find no changes in the transmitter. The only thing I can think of is the fact that the tubes are installed horizontally, which causes the elements to warp and eventually break or short.
Continental 816R2 transmitter, WFLY, Troy, NY
I am thinking we may try to convert the driver section of this transmitter to a solid state unit. The transmitter itself is 24 years old, but is still works and sounds great. I’d hate to get rid of it because of its driver section.
Yesterday, January 18, 2012, I blacked out engineeringradio.us for the day in protest of the internet censorship bill working its way through congress colloquially known as SOPA or PIPA. There were some 17,000 or more others that did the same.
SOPA PIPA protest screen shot
If the internet is indeed the new media, destined to replace the old media, then having in place draconian restrictions that allow the government to block websites and content with no due process for the website owner is censorship, plain and simple. Imagine a country where the government can come in and shut down any newspaper, TV station or Radio station, give no reason other than some weak statement about copy write laws. See also: China, North Korea, Cuba, Soviet Russia, etc.
It is important to check the corporate power in this country. It is widely reported that Congress has a 9% approval rating. It is also hard to imagine their approval rating is actually that high. While signing petitions and writing senators and congressman may provide some relief, the shortest path to ending this is to boycott the corporate sponsors of the legislation. Hitting companies bottom line will speak louder than any internet protest, petition, letter writing campaign, etc. Thus, if so inclined, here is a list of producer companies that like the idea of internet censorship.
Right after Tropical Storm Irene, it was noted that the STL signal strength at the WHUD transmitter site was low. Normally it was 300+ µV, now reading around 100 µV, which is a problem. Upon further investigation, it was revealed that the STL transmitter on the intermediate hop had higher than normal reflected power.
Time to call the tower crew.
The STL transmit antenna for WHUD’s STL (WPOU464) hop is a Scala Paraflector (PR-950), mounted at the 280 foot level on this tower:
Scala PR-950 on a guyed tower
The fact that it happened after a major storm and the transmitter was showing higher than normal reflected power indicates a problem with either the antenna or the jumper between the 7/8″ Cablewave coax and the N connector on the antenna. A measurement with a spectrum analyzer shows very high return loss:
WHUD STL antenna return loss
This shows distance to fault 413 feet, with a return loss of -7.4 dB. That distance is either near or at the antenna and -7.4 dB indicates a lot of reflected power. We had the tower climber take apart the jumper connections and terminate the jumper with a known good 50 ohm load. The return loss did not change. We then had him swap out jumpers and reconnect to the antenna. That did the trick:
WHUD STL antenna with new jumper
Much better, most of the power is now being radiated by the antenna, the VSWR is 1.02:1. The impedance bump at 51 feet is a sharp bend in the coax where it is attached to an ice bridge. Reconnecting the transmission line to the transmitter and turning it on confirms that all is normal again. The problem with the jumper was found in one of the connectors, it was full of water.
Water contaminated Andrew flexwell connector
I cut away the boot, water had entered the connector from the back because waterproofing and tape was not applied all the way to the coax. This was installed in 1998 when the station moved from Peekskill to their current location in the town of Fishkill. The fact that it happened now in the nice weather when Mt. Beacon is still accessible and not in the middle of winter means the radio gods are smiling on us.
There is a propensity among radio engineers to save old equipment. Sometimes I look at something and think, “Man, that cost a lot of money ten or twenty years ago.” Truth be told, much of what is saved will never be used again. This equipment should be scraped or donated to someone who might find it useful. One thing that is most appreciated by Amateur Radio (AKA Ham) operators are old 1 KW tube type AM transmitters. Ham operators love these things, and with good reason.
A fair amount of repair work, some cleaning and a bit of reworking will turn what might have been a useless dust collector into a 160 or 80 meter AM rig and with a good story to boot.
Personally, I’d rather see a Gates BC1T or RCA BTA1R off to a new home than off to the scrap yard. To that end, today we unloaded the BC1T at WLNA to a willing ham. This particular transmitter had last run in 2001 or so and was used as a spare parts supply for other BC1T transmitters owned by the same company. There was no way it would ever work again and truth be told, it really wasn’t needed any longer anyway. Since the Harris MW5B was replaced as the main transmitter by a BE AM6A, the backup transmitter was never used.
Gates BC1T transmitter
John Aegerter, a frequent commenter on this blog, drove all the way from Madison, Wisconsin to pick it up. Prior to pick up, I removed all of the tubes, transformers, crystals and glass envelope time delay relays. I packed up the glass objects in a box.
Gates BC1T tubes, transformers and spares
There were several spare tubes and parts which are no longer needed. These went with the rig, along with what ever manuals I could find.
Gates BC1T loaded into pickup truck
The transmitter was then loaded into the back of a Dodge Ram 2500 pickup truck and tarped for it’s trip back to Wisconsin.