The inglorious task of AM antenna array maintenance

AM radio stations are rough customers. They frequently operate on the margins, both in terms of ratings and revenue. Their transmitter plants are complex and very often have been on a reduced maintenance schedule for years, sometimes decades.  Those of us that understand the operation of AM transmitter plants and all their quirky behaviours are getting older.  I myself, feel less inclined to drop everything and run off to the AM transmitter site when things go awry.  Seldom are such efforts rewarded, much less acknowledged.  Station owners are also finding that their previous demands are unrealistic.  For example, time was that any work that takes the station off the air had to be done after midnight.  These days, I can tell you, I will not be working at your radio station after midnight.  You can find somebody else to do that work.

Thus, today, we took this particular AM station off the air from Noon until 3 pm to diagnose and repair a problem with the four tower daytime array.  Once again, this involved a shift in common point impedance and a drastic change in one tower’s current ratios.

Antenna Tuning Unit, mice have made a mess
Antenna Tuning Unit, mice have made a mess

In all fairness to the current owner, this ATU reflects years of neglect. At some point, mice made a home in here and created a mess. The ATU smells of mouse shit, piss and mothballs.  It is full of mouse droppings, grass seeds and fur.  All of the ATUs in this array are in similar condition.

Paper wasp, inside ATU
Paper wasp, inside ATU

It was warm enough that the wasps were active, if not a little bit lethargic.

Broken stand off insulators in ATU
Broken stand off insulators in ATU

This coil is being held up by the tubing that connects it to other components. When the ATU was built, no nylon or cork bushings were used between the insulators and the wall of the ATU they were mounted on. Heat cycling eventually did all of the insulators in.

Catwalk to the other towers
Catwalk to the other towers

Catwalks to the other towers. At least the swamp grass has been cut this year, it is only four feet tall instead of ten.

Tower base
Tower base

The tower bases are all elevated above the theoretical maximum water level. The ATUs are also up on stands with platforms build for maintenance access.

ATU Work "platform"
ATU Work “platform”

I cannot even blame the current owner, who has spend considerable money to make repairs and upgrades to this site. It is very difficult and very expensive to catch up with deferred maintenance. Sadly, most AM stations we encounter have similar or worse problems.

I think it is too late to save many of these AM stations.  The technical issues, lack of revenue, perceived poor quality, lack of good programming are all taking their toll.  At this point, the hole is so deep there is no hope of ever getting out.  The FCC’s faux interest in “revitalization” followed by two years of stony indifference seems to be a final, cruel joke.

It is kind of tragic, in a way

Working on another AM directional station (WGDJ) which was damaged by lightning recently. In this case, the antenna array controller ceased working and one of the towers in the daytime pattern was out tolerance. Before we stared working, I told the owner to have all the vegetation cut down around the towers. This is what we ended up with:

WGDJ catwalk, East Greenbush, NY
WGDJ catwalk, East Greenbush, NY

I can’t really fault them for this, but it does make work more difficult.  That strip of tall green grass; that is the catwalk. The grass itself is called Phragmites, which is tall, tough, reedy stuff that can scratch and cut person unaware. The array is in a low swampy area next to the Hudson River in East Greenbush, NY. Stepping off of the catwalk, one can sometimes find solid ground, or find ones feet six inches under water.

WGDJ tower one ATU cleanout
WGDJ tower one ATU clean out

This is Mike cleaning out the mice and bees nests out of the tower #1 ATU. Notice the can of bee spray in his back pocket.  This was after he was stung in the forehead.

Mouse nest, WGDJ daytime ATU coil
Mouse nest, WGDJ tower #5 daytime ATU coil

This mouse nest, at the attendant dead body in it, was responsible for a -10 degree phase shift in the daytime pattern for that tower. I hate cleaning this stuff out, it is a dirty, nasty job but necessary nonetheless. While doing this work, I wore gloves and a dust mask. The entrance hole where the AC power and control cables come into the bottom of the ATU was plugged up with some steel wool.  There is still a bad capacitor in this ATU for the daytime array, that damage was likely caused by lightning.

At the end of the day, we repaired the antenna array/phasor controller; bad AC transformer and rectifier bridge and several bad logic steering diodes for tower 4 and 5, cleaned out all the vermin nests and isolated the remaining problem with the daytime antenna system.  Parts should be in next week to finalize repairs.

All in all, not a bad day’s worth of work.

WKNY, Kingston, NY

This is another one of those, ahem, AM success stories. WKNY is on 1490 KHz, 1,000 Watts day and night from a transmitter site that is located very close to it’s target audience of Kingston. It signed on on December 16, 1939 broadcasting 100 watts on 1500 KHZ according to the Broadcasting Yearbook 1940 edition.

WKNY transmitter site location
WKNY transmitter site location

The transmitter location is the key to this station’s good signal over Kingston. Even though it is a class C AM station, when driving around the Kingston city limits there is no electrical interference or night time co-channel interference.  The reason for this is because most of the city limits are within 2.5 to 3 miles (4 to 4.8 km) from the tower.

WKNY transmitter building and tower
WKNY transmitter building and tower

This is the original transmitter building and tower.  Like many old AM transmitter sites, this one is located in a low, swampy area.  The tower is electrically tall for 1490 KHz, at 92 meters (305 feet)  it is 163 electrical degrees. Something else that may contribute to the station’s performance.

WKNY tower base
WKNY tower base
WKNY tower
WKNY tower

WKNY tower, typical design of a uniform cross section guyed tower from the late 1930’s to late 1950’s.

WKNY transmitter
WKNY transmitter

WKNY transmitter. Another Nautel ND-1 series transmitter. Nothing every breaks or goes wrong.

Air studio, WKNY Kingston, NY
Air studio, WKNY Kingston, NY

The air studio has an AudioArts R-60 console. For an inexpensive audio console, these things sure seem to last for a long time. I think this one was put in in 1997.

Talk Studio, WKNY KIngston, NY
Talk Studio, WKNY KIngston, NY

A small talk studio is used to originate local programming of interest. This morning, I was listening to “Speak Out With Jody McTague,” a local interest program which was discussing the impacts being felt in the Kingston area due to the “Affordable Health Care Act.”

WKNY production studio
WKNY production studio

The production studio has a rather old Harris rotary pot console from the 1980’s.

Of course, all of this equipment makes radio transmission possible, but what makes radio itself is the local people working at the station and bringing relevant information to the area.  I know a lot of very smart people are working on the “solution” to the AM problem.  It really has to do with the programming.

Happiness is: An AM directional array at licensed values

Last week I did some repair work at WDDY in Albany NY. It seems the sample line on one of the towers was melted in half by a lightning strike. This station uses sample loops up on the tower for their directional antenna monitoring system.

WDDY antena array, Albany, NY
WDDY antena array, Albany, NY

As it happened, the sample line in question was on the reference tower, which makes everything else meaningless.  Before the meltdown, there were several years worth of maintenance logs which showed the previous values for current ratio and phase relationship.

With the transmitter turned off and locked out, I removed the damaged section of line from the base of the tower to the RF choke coil in the tuning house.  Where the sample line came off of the base of the tower, there was a UHF type connector which had been improperly applied.  Using spare parts, I fixed that connector, then spliced the line into place.  Upon power up, the transmitter and antenna readings returned to there previous values, which were slightly out of tolerance.

Thus, some phasor tuning was needed.  There are not too many people left that can properly tune an AM phasor.  All of the control interact with each other; moving the power or phase to one tower will likely effect all of the other towers and possibly the reflected power on the transmitter.  This phasor was made in the 1970’s by Multronics with what looks like all RCA parts.  Multronics, I think, was John Mullaney who is more known for the folded unipole antenna.  In anycase, after a good few hours of careful hand cranking and a run out to the reference tower to move a coil tap, here are the results:

WDDY tower one, reference
WDDY tower one, reference
WDDY tower two
WDDY tower two
WDDY tower three
WDDY tower three
WDDY forward/reflected power
WDDY forward/reflected power

Not bad for a day’s work.