Engineering Radio

My former employer thinks he knows better than anyone what to do in every given situation.  ”Mister,” as he is “affectionately” known, has a legendary cheap streak.  When I worked for the company, every year there would be a debate on whether we should plow and maintain the road to a certain transmitter site.  Mind you, this is not just any transmitter site, but the transmitter site of the number one billing station of the entire group of 35 stations.  It is located in the wealthy suburban setting of market Number One and bills more than most of their other markets combined.

Naturally, when I was there, I put up a stiff fight to make sure the road got patched and plowed.  Oh they would scream and nash their teeth about how unfair it was, and can’t we do this or do that, etc.  This went on every year for the entire ten years I worked for the company.  For my part, I just ignored it.  Back in October of last year, when I was first starting to see the handwriting on the wall, there was this clandestine meeting with the other residents on the road which I was not invited to.  You see, the lower half of the road has houses on it.  Mister thought that the residents of the road should chip in for the road plowing.  When they refused (because they were already plowing the lower part of the road themselves) he said we would absolutely, positively ,100% not be plowing the road this winter.

I departed the company in January.  Since then, the upper part of the road was not touched.  Then came last week’s blizzard.  Prior to the blizzard, the generator fuel tank was 9/10 full.  The power went out on Wednesday during the first storm.  I called the General Manager for the radio station on Friday and told him that the generator would need fuel soon and asked if the road had been plowed.  He said they were working on it and it should be done on Saturday.  I told him that we needed a fuel truck up there ASAP otherwise they would be going off the air.  He said he was on it.

Sunday morning at 6:30 am, the generator ran out of fuel.  Naturally, my phone rings.  I begin calling around all the fuel oil companies in the area to see if I can get a Sunday delivery.  I finally arrange something and we also get a 4WD pickup with a 100 gallon day tank to meet us there.  When I arrive at the site at 9:30 am, a backhoe was just starting to clear the upper part of the road.  The snow is knee deep and there is a layer of ice under it.  It took until about 1:30pm to get the road cleared enough to get the 4WD pickup, with tire chains near the generator to transfer fuel.  Then, because the fuel pump sucked air, we had to bleed the injectors, reset the faults, etc.  We finally got the generator started around 2:00pm.

So, let us compare costs:

Plowing the road cost about $800.00-$900.00 per storm.  This year, there were five to six storms where the road needed to be plowed. Total $4,500.00

Last Sunday, the station was down for about 7 hours.  I’d say that station likely bills $150.00 per unit on a Sunday morning, 10 units an hour so they lost $10,500.00 by being off the air.  Then there is the backhoe needed to clear the road.  A backhoe was needed because there was so much snow on the road that a regular snow plow could not move it, especially plowing up hill.  That cost $1,500.00.  Then there is my overtime and the guy with the 4WD pickup, another $1,440.00.  Total cost to plow the road and get the station back on the air, somewhere in the neighborhood of $13,440.00.

So, yeah, Mister is really saving money.  How’s that working out for you, a$$hat?

In case you have wondered it yourself:

4CX3500A

This is an EIMAC 4CX3500A which came out of a Harris HT5 transmitter. As you can see it the ceramic cracked in half. When I arrived at the transmitter site, the unit was on, full plate voltage, no plate current, no overload lights. I figured it might be something with the tube, so I tried to pull it out, but only the top half came. One of those “Ah ha” moments.

Fortunately, there was a working spare at the transmitter site and we got back on the air relatively quickly.  That, in and of itself is amazing considering the building that this transmitter lived in.  One of those abandond former studio sites with the transmitter jammed into a back room somewhere.  To get to it, one has to dodge pigons, beware of rats and wade through piles of garbage.

It is a little bit hard to tell in this photograph, but there are to “cages” which are the Screen and Grid.  The post in the center is the filament/cathode and the top detached part is the plate/anode.  In an FM transmitter, the exciter is coupled to the grid, the screen accelerates electrons toward the plate and therefore controls the power, the plate collects the electrons and is coupled to the output stages and the antenna.  Good stuff.

Another picture from my collection, this one is the back side of a power supply module from a Broadcast Electronics AM6A transmitter:

Bang!

It happened during power up from 1 KW to 5 KW and it was quite loud, as I was standing right next to the transmitter.  The exploded part is a 0.1 uf capacitor that looks like an add on.  In fact, some of the other power supplies don’t have it.  It also took out the 20 amp slow blow fuse.

I like the exploded look of the board, kind of like on The Road Runner, when Wyle E. Coyote looks into a box and something explodes.

This is the only problem I have had with this particular transmitter.

Another example from my blown up shit collection, pictures archive:

Burned out harmonic filter, BE FM-30T transmitter

The harmonic filter from a Broadcast Electronics FM-30T.  This actually started in the bullet connector to the 3 inch hardline on the output side of the filter.

Burned out 3 inch hard line section

Again, I did not install this myself, someone else did.  Cutting 3 inch hard line is pretty straight forward.  When using a field flange, the outer and inner conductors are cut flush.  Both conductors should be de-burred and filed smooth.  It only takes a little thing to start an arc with 30 KW of FM power, so once again, attention to detail is key to avoiding these things.

Fortunately, BE sent along replacement parts for the harmonic filter and the line section was replaced.

This is from my burned out shit collection, pictures section:

Broadcast Electronics AM5E power supply

It is a power supply from a Broadcast Electronics AM5E transmitter.  Here is another view:

Broadcast Electronics AM5E power supply mating connector

As you can see, there was a small fire started in the mating connector for the transmitter wiring harness.  I did not install this unit so I have no way to know for sure what happened, but I suspect that the mating connector was not pushed all the way in during installation.  In this business, really in all engineering fields, it is the little details that will catch up with you.

I know that one of the stations I used to work at had a fire at their electrical service panel at the FM transmitter site, after they installed a new transmitter.  This happened after I departed for greener pastures.  In any case, it is very important to torque the connections on any service disconnect or circuit breaker to the panel manufacture’s specifications.  I also check the lugs every so often with a Fluke 62 mini IR temperature meter. Any loose connections will show up as hot spots, which can be fixed before the fire breaks out.

All current carrying electrical connections should be double checked for solid connections before the transmitter is turned on, then check periodically thereafter for heat buildup and or heat damage.

I read through the news coverage of the vandalism at the KRKO transmitter site.  Apparently there is some group of idiots people running around insisting that radio towers are bad for the environment and people’s health.  These are the same ones who have torched SUV’s and burned high end housing developments down.  Naturally, no pollution is released into the environment during these acts, else they would be hypocrites.

They make these claims with no merit or scientific basis, instead relying on base fears to make people go crazy, either temporarily or permanent like.  It is actually a pretty good motivator as both political parties and all sorts of fringe truthier, birthier, and others have discovered.  If enough people insist that it is true, than it must be so.

Unfortunately there is always some idiot around who thinks it is his or her duty to take action, to protect the rest of us from some terrible fate.

In the meantime, some security cameras at the transmitter site might be a good investment.  Chances are, these Earth Liberators that sneak around with bolt cutters and hack saws will likely think twice if there is any chance of themselves going to jail.

By the way, those KRKO towers looked like self supporters which would have been very difficult to get down.  Did they rent that excavator, or was that some construction equipment left unattended?

This is a picture of an exploded battery on a 45 KW backup generator:

850 CCA battery exploded during generator startup

This happened during a thunderstorm.  The smoking crew was out on the back porch, during a thunderstorm (you have to have your priorities I suppose) and witnessed the entire incident.  What was told to me was lightning stuck the generator.  I find that improbable, since there are many metal objects scattered around the area that are much taller.  What likely happened was lightning stuck something close by, causing the power to drop out momentarily.  This caused the generator to turn over.  The battery was likely low in electrolite, so there was an internal arc and the thing exploded in short order.

These events happend in rapid sucession, giving the illusion that lightning struck the generator.

I removed the old battery and hosed the inside of the generator out with copious amounts of water.  There is nothing that can be done about the spilled electrolite, since it was likely washed into the storm sewer during the storm.  After replacement of the battery, I tested the generator and all is well.

One of our stations relies on a T-1 (DS-1) to relay audio from the studio to the transmitter site (STL).  This station started as a piece of paper, no format, no staff, no real estate, no studio equipment.  There was a transmitter and an antenna installed on a leased tower site.

That being said, corners were forcibly cut.  Instead of installing a microwave STL system, a T-1 was ordered because we had a T-1 multiplexor.  Fast forward several years… The station is now successful, making a decent amount of money and having a popular format.

The station has two T-1 circuits on different cables with an automatic switcher.   Yesterday afternoon, the inevitable happened, both T-1s went out, along with most of the other TELCO circuits in the surrounding area.  A construction crew cut two 3600 pair cables a mile down the road.  The TELCO is racing to restore the service to all of the tenants on that tower by rigging a temporary aerial cable.

Now the mad scramble ensues with conflicting requirements from the wacky program director.  Screw it, I grabbed one of the AudioVault express machines and took it to the transmitter site.  They are back on the air with a radio station in a box playing music until the T-1 gets fixed.

This site has had numerous problems since we have owned it.  In the 5 years since we launched the format, there have been six T-1 outages longer than 24 hours.  For back up, we have tried an ISDN line, a 3G wireless card in a computer, and a second T-1 circuit.  None of these have proved reliable as most circuit outages involved a cable cut, and multiple circuits were effected.

The real solution is a microwave STL, either a conventional 950 mHz system, or a 2.4 or 5.8 gHz last mile system.  Either would work better than what we have now.  Station ownership, they don’t want to hear it.

Update: This took until Friday, September 4th to repair, for a total outage of 9 days, 2 hours and 26 minutes.  During that time, the station remained on the air with the AudioVault server at the transmitter site and the program director updating it twice per day with voice tracks and commercials.

For about 4 years, I lived in a house next to a four hundred foot radio tower.  Although I never actually saw lightning strike the tower, I heard it several times.  Like everything else, after a while, you get used to it.

This is a video of lightning hitting the WSIX STL tower in Nashville, TN. The camera work is a little unsteady, the strike occurs around the 1:36 mark:

Yep, that is what it is like.

File under: Why we check the tower lights every day (or have an automated tower light reporting system):

56 years ago, on September 16, 1953 American Airlines flight 723 flew between the center and northeast towers of the WPTR antenna system while attempting to land at Albany County Airport.  The plane crashed about 3/10 mile away near NY route 5 (Central Avenue) killing all 28 persons on board.  To date, this is the worst aviation accident in the Albany, NY area.

Several years ago while cleaning out different AM transmitter site, I found a bunch of files about this accident in the trash bin.  It seems that some engineer had moved a file cabinet during the great consolidation of the 1990’s to the wrong transmitter site.  In any case, I rescued the file and for your reading pleasure, have scanned the following documents:

Original telegram to FCC in Washington DC regarding tower/aircraft colision

Retel WPTR north and center towers struck three hundred foot level 0930 morning 16 September by American Airlines Convair.  Damage inspected afternoon 16 September by representative Zane Construction and afternoon 17 September by engineer Ideco tower used in array.  Both report slight damage to center tower requiring straightening above 300 foot level.  North tower has two legs bent result of wing passing through tower 18 inches above top guys at bolt intersection.  Tower above bent and twisted but all right unless subject to high east wind.  Impact sheered north beacon clevises and shattered glass.  Replacement ordered and beacon restoration expected early next week.  Measurements of directional pattern afternoon 16 September show pattern unchanged and mulls, base currents and loop currents within tolerances except center loop current which reads ten percent low.  Indications are center pickup loop has been jarred and pattern unaffected.  FCC representative Turnbull who arrived noon Wednesday concurred.  No time lost.   Operating at full power

George Wetmore, Assistant Genl Mgr, Radio Station WPTR

This is the statement of the transmitter engineer on duty at the time of the crash.

Statement from the Engineer on duty at the transmitter site

I, Robert S. Henry engineer for Patroon Broadcasting Co. would like to make this statement concerning the collision of an American Airlines Plane with our transmitting towers.

On Wednesday morning September 16, 1953 I was on duty alone at the WPTR transmitter when at approximately 9:30 A.M. a low flying plane was heard overhead. The carrier trip circuit which protects the transmitting apparatus from sudden overloads at the antenna almost instantly actuated and a low sound of explosion followed about 3 seconds later. I ran to the back door of the transmitter in time to see what proved later to be aluminum sheets fluttering down through the fog. I estimate the ceiling at the time to have been approximately 75 feet and not sharply defined. The centre (sic) tower of our three tower array swayed violently for approximately for approximately (sic) 1 minute. At the time I knew a plane had hit the tower but it was above the ceiling and invisable to me. I called W. R. David and George Wetmore and the incident was reported to the Albany airport.

Back in these days, the studios were located at the Hendrick Hudson Hotel in Troy, the transmitter site was manned by a licensed transmitter engineer when ever the station was on the air.

What is amazing is that the IDECO towers remained standing after being struck by Convair 240, a pretty good sized aircraft.

Convair CV-240

Official report by the International Civil Aviation Organization:

American Airlines’ Flight 723 was a scheduled flight between Boston, and Chicago, with intermediate stops among which were Hartford (BDL), and Albany (ALB). The CV-240 arrived at Bradley Field at 06:57. Weather at the next stop, Albany, at this time was below the company’s landing minimums, but was forecast to improve to within limits by the time the flight arrived there. Departure from Bradley Field was made at 07:14. Because of poor visibility at Albany, several aircraft were in a holding pattern. The special Albany weather report issued at 07:50 indicated thin obscurement, ceiling estimated 4,000, overcast, fog, visibility 3/4 miles. Two aircraft left the holding pattern, attempted to land, but both executed a missed approach procedure. A third airplane landed at 08:16 following an instrument approach to runway 19. Immediately following this landing, Flight 723 was cleared to make an instrument approach to runway 19. Three minutes later the flight advised the tower that its approach was being abandoned because the aircraft’s flaps could not be lowered.
At 08:30 Albany Tower reported:”All aircraft holding Albany. It now appears to be pretty good for a contact approach from the west. It looks much better than to the north.” Flight 723 was then cleared for a contact approach to runway 10. On finals for runway 10, the Convair descended too low. The right wing of the aircraft struck the center tower of three radio towers at a point 308 feet above the ground. The left wing then struck the east tower. Seven feet of the outer panel of the right wing including the right aileron and control mechanism from the center hinge outboard together with 15 feet of the left outer wing panel and aileron separated from the aircraft at this time. Following the collision with the towers, ground impact occurred a distance of 1,590 feet beyond the tower last struck. First ground contact was made simultaneously by the nose and the left wing with the aircraft partially inverted.
The weather reported at the time of the accident was thin scattered clouds at, 500 feet, ceiling estimated 4500 feet, broken clouds, visibility 1-1/2 miles, fog.

PROBABLE CAUSE: “During the execution of a contact approach, and while manoeuvring for alignment with the runway to be used, descent was made to an altitude below obstructions partially obscured by fog in a local area of restricted visibility.”

The above reports notes that the aircraft traveled 1590 feet and struck the ground partially inverted.  I do not know what the flaps up landing speed of a Convair CV-240 is but the cruising speed is 280 MPH.  It would be safe to say the aircraft was traveling in the 120 to 130 MPH range or about 220 feet per second.  At that speed, it was likely airborne for about 7 seconds after it hit the tower.  Enough time to look out the window, realize what was happening and say “Oh, Shit!”

IDECO towers WDCD antenna system, northeast tower is farthest

IDECO stood for the Internation Derrick Company, they build cranes, derricks and bridges as well as radio towers. Apparently they made pretty good stuff because those same towers are still standing today.

Not that checking the tower lights would have averted disaster in this case, it appears to be pilot error compounded by bad weather that caused this incident.  But there have been more recent aircraft/radio tower accidents, some of which have involved possible faulty tower lights.  I wouldn’t want that on my conscience.