July 2014
M T W T F S S
« Jun    
 123456
78910111213
14151617181920
21222324252627
28293031  

Archives

Categories

Cleaning up

We removed this old Harris BC5HA transmitter recently:

Harris BC5HA, WROW Albany, NY

Harris BC5HA, WROW Albany, NY

It was installed new in 1974, when the station moved to this site from another one a few miles up the road. It functioned as a main transmitter until the BE AM5E was installed in late 2001. The BE transmitter, other than a power supply issue, has been a solid, reliable unit. Truth be told, the last time the BC5HA ran was in 2006. After that, the unit refused to run, a bad modulation transformer was suspected. It was deemed not worth it to repair, thus, out the door it goes. We ended up giving it to a local contractor who scrapped the metal in lieu of payment for his labor.  The only thing he could not take was the aforementioned modulation transformer, which is full of PCB’s.  That will have to be hauled away by a licensed disposal company.

Broadcast Electronics AM5E, WROW Albany, NY

Broadcast Electronics AM5E, WROW Albany, NY

We may be getting a second hand Nautel transmitter from another station as a backup transmitter.  If that comes to fruition, then a couple of racks can be added to the end of the Phasor/transmitter/transmitter row and the wiring for the remote control and STL can be simplified and neatened up.

GE BT-25 Mystery transmitter site

Update: Thank you, Jim.  The mystery site is KFIG (formerly KFRE) in Fresno, CA.  This is what the transmitter building looks like from the outside today:

KFIG transmitter, circa 2011

KFIG transmitter, circa 2011

In the previously mentioned the rescued file cabinet and along with the WFLY transmitter site construction information, I also found these interesting photographs:

Mystery AM transmitter site

Mystery AM transmitter site, plate 9296

I do not know what transmitter site this is. From the photo, it has a two tower (guyed) directional antenna. It looks to me to be somewhere out west. The transmitter is a General Electric BTA-25 or BT-25, same as the former WPTR and WCKY transmitter. I know this back hallway well:

Mystery AM transmitter site, back hallway of GE BT-25.  Plate 9300

Mystery AM transmitter site, back hallway of GE BT-25. Plate 9300

This is the transformer vault:

Mystery AM transmitter site, transformer vault.  Plate 9297

Mystery AM transmitter site, transformer vault. Plate 9297

Modulation transformer and three pot plate transformer:

BT-25 modulation transformer.  Plate 9299

Mystery AM transmitter site, GE BT-25 modulation transformer. Plate 9299

I would say that these may be promotional photos, because of the spotlessly clean installation and the plate numbers on each print.  Unfortunately, there are no pictures of the front of the transmitter, including the operator console.

Does anybody know where this is?

Bucket Trucks and Landing Craft

Hopefully that title is descriptive enough:

ATT bucket trucks, , mobilized via landing craft to Pleasure Beach

ATT bucket trucks, , mobilized via landing craft to Pleasure Beach

We loaded a couple of ATT bucket trucks on a landing craft and waged an assault on Pleasure Beach.  This is to finalize the repair work from Hurricane Sandy last year.  The other factor is the construction taking place on the Island.  The City of Bridgeport is constructing a park, which involves extensive repairs and renovations to the buildings.  Construction vehicles driving under the old lines have ripped them down several times, thus repairing the lines on the new utility poles was necessary.

ATT truck offloading

ATT truck offloading

ATT truck offloading

ATT truck offloading

ATT is the LEC for the Bridgeport area, something they don’t do in most other parts of the country, from what I am told.

Landing Craft Challenger

Landing Craft Challenger

It took approximately four hours to complete this work and reload the trucks back on the landing craft.  The boat itself looks like a slightly modified LCM (Landing Craft, Mechanized), which were produced from 1943 onward.  This is an LCM-8.

WICC towers

WICC towers

WICC towers almost in line, I was about one second too late with this shot. This would be “down the bore” of the daytime pattern into downtown Bridgeport.

WICC towers

WICC towers

Another shot of the WICC towers. These were designed to hold up a horizontal T top wire antenna strung between the two of them.  At some point in the early thirties, somebody realized that the tower itself could be excited as a vertical radiator and the antenna configuration was changed. Up until the mid 1970′s there was a horizontal wire which supported third wire element hanging between the two towers, making it a three tower directional array.  This was removed and it was then that the current phasor and two tower DA-2 system was installed.

All in a day’s work.

WROW

WROW 590 KHz, Albany, NY is another one of those successful AM stations.  They have a music format, which I would characterize as a blend between nostalgia and oldies.  They do well in the Albany book and most importantly; make money.  The Wikipedia entry is a little dated, as they have had a music format for over four years now.  The low dial position helps, as I can get the station up near the Canadian border and most of the way down to Poughkeepsie during the daytime pattern operation, which is better than across town WGY, 50,000 watts non-directional.

Here are a few pictures of the transmitter site:

Broadcast Electronics AM5E, WROW, Albany, NY

Broadcast Electronics AM5E, WROW, Albany, NY

WROW main transmitter

WROW transmitter room

WROW transmitter room

WROW transmitter room; main and backup transmitters, phasor, equipment rack, etc.

RCA BTA1AR former backup transmitter

RCA BTA1AR former backup transmitter

The former backup transmitter for WROW-AM. This was moved from the original transmitter site, located a few mile north of the current transmitter site in Glenmont, NY. The current transmitter site was constructed in 1974.

Onan diesel generator

Onan diesel generator

Backup power

WROW antenna array, three tower DA-2

WROW antenna array, three tower DA-2

WROW antenna array. The station transmits with 5,000 watts daytime and 760 watts night time. The towers are slightly tall at 105 electrical degrees. It is hard to do tall towers at the low end of the dial because the towers get very tall. These are 149 meters (488 feet) tall.

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.

As requested: The old WSBS studio building

Alan asked that if I should ever find a picture of the old WSBS studio building to publish it.  Here it is:

WSBS old studio building

WSBS old studio building

I found this above the coffee machine in the lobby, nicely matted and framed.  I didn’t want to ruin the framing job, so I took a picture of the picture under glass and cropped it, thus the quality could be better.

I believe this is the original tower from 1959.  The current tower stands on a taller concrete pedestal and is further away from the road.  I think the roadway was widened and raised at some point, thus the new building sits higher in relationship to the tower base.  In any case, it little bit of radio history.

The Nautel XR6 AM transmitter

I’ve been away working in Burlington, VT (WVMT, 620 KHz, Burlington)  for the last coupla, installing this nifty Nautel transmitter:

Nautel XL6 transmitter, WVMT Burlington, VT

Nautel XR6 transmitter, WVMT Burlington, VT

I like the Nautel units, both AM and FM;  they are well designed, well built, rugged transmitters.  I have lost track of how many of these units we service in the field, partly because they are becoming pretty much standard equipment at all of our installations.

Continental 315R-1 AM transmitter, WVMT, Burlington, VT

Continental 315R-1 AM transmitter, WVMT, Burlington, VT

The transmitter it is replacing is a Continental 315R-1, which is based on the Collins Power Rock design.  It is a PWM transmitter with a 15,000 volt power supply.  In their day, these were not terrible transmitters, however, like their Harris MW-5/10/50 PDM brethren, frequent thorough cleaning is required to keep the dirt/dust from arcing over.  Unfortunately, it is becoming more and more difficult to obtain parts for these units. This transmitter was installed in October of 1983, thus, almost thirty years of service is quite enough.  This unit we did not cut up and scrap, rather, it is sitting by the back door, waiting for any takers.

Continental 315R1 modulator/RF sections

Continental 315R-1 modulator/RF sections

The interior of the Continental 315-R1 transmitter.  Modulator section is on the left, RF section is on the right.

The good news is, WVMT is another one of those “successful AM station” stories.  You know, the kind of station that has local programming, local sports, news, community presence and most importantly, makes money.  For all those diligently studying the “AM Problem” for the up and coming NAB conference this April, here is a clue: It’s the programming…

Nautel XR6 transmitter, wvmt Burlington, VT

Nautel XR6 transmitter, WVMT Burlington, VT

This is the Nautel XR-6 on the air.  Positive peaks, anyone?

AM modulation monitor

AM modulation monitor

We turned that down a little bit.  Also, the station does not run AM stereo, the AM stereo mod monitor is simply a usable relic of a bygone era.

WVMT is noted as the first radio station licensed to the state of Vermont, signing on on May 10, 1922.  It has a three tower directional array located down in the swamp.  For some idea of perspective, it is 1,150 feet (350 meters) from the transmitter building to the center tower, the towers are 411 feet (125 meters) tall spaced 405 feet (123 meters) apart.

WVMT three tower directional antenna array, Burlington, VT

WVMT three tower directional antenna array, Burlington, VT

WVMT antenna system from back of transmitter/studio building.  That is a long walk over rough terrain in the middle of the night or anytime really, but especially in the middle of the night.

Series surge suppressor

Radio facilities, particularly mountain top transmitter sites, are prone to power transients. The causes can be varied, but most often, lightning is the culprit.  Long power transmission lines to the site are vulnerable to direct strikes and EMF induced spikes from nearby strikes.  Other issues, such as switching transients, load fluctuations, and malfunctioning equipment can lead “clear weather” outages.  Of course, the best way to deal with such things is prevention.

Power line surge suppressors have been around for quite some time.  They usually take the form of a MOV (Metal Oxide Varistor) connected between the hot leg and neutral or ground.  There are a few differences in designs, however.  Typically, most facilities employ a parallel surge suppressor.  That normally take to form of an enclosure hung next to the main power panel with a group of MOV modules in it.  The MOVs are feed from a circuit breaker in the panel.  Like this:

LEA parallel surge suppressor

LEA parallel or shunt surge suppressor

This is an LEA three phase 208 volt shunt surge suppression unit, which has MOVs between all phases to ground and each other.  That is connected in parallel to the electrical service with the circuit breaker disconnect.  These function well enough, provided there is a good bit of series inductance before the unit and also, preferably after.  The series inductance can come from many sources, including long secondary leads from the utility company transformer or electrical conductors enclosed in metal conduit, particularly rigid (verses EMT, or FMC) metal conduit.  The inductance adds a bit of resistance to the transient voltages, which come in higher than 50 or 60 Hz AC waveform.

A better method of transient protection is the Series Surge Suppressor.  These units are installed in line with the incoming service and include an inductor to add the required series resistance coupled with MOVs and capacitors.  Most series surge suppressor also filter out harmonics and RF by design, something desirable particularly at a transmitter site.  Series surge suppressors look like this:

LEA DYNA systems series surge protector

LEA DYNA systems series surge protector

This is a LEA three phase 240 volt unit.  As in the other example, all phases have MOVs to neutral and each other.   There are MOVs and capacitors on the line and load side of this unit (line side is the bottom of the inductor).  A basic schematic looks like this:

Series surge suppressor basic schematic

Series surge suppressor basic schematic

A few things to note; MOVs have a short circuit failure mode and must be fused to protect the incoming line from shorts to ground.  MOVs also deteriorate with age, the more they fire, the lower the breakdown voltage becomes.  Eventually, the will begin to conduct current at all times and heat up, thus they should also be thermally fused.  MOVs that are not properly protected from over current or over temperature conditions have the alarming capacity to explode and/or catch on fire.  From experience, this is something to be avoided.  Matched MOVs can be paralleled to increase current handling capacity.

The inductor is in the 100 µH range, which adds almost no inductive reactance at 60 Hz.  However, it becomes more resistive as the frequency goes up.  Most transients, especially lightning, happen at many times the 60 Hz fundamental frequency used in power distribution (50 Hz elsewhere unless airborne, then it may be 400 Hz).

Capacitors are in the 1-10 mF range and rated for 1 KV or greater as a safety factor.  The net effect of adding capacitance is to create a low pass filter.  Hypothetically speaking, of course, playing around with the capacitance values may net a better lowpass filter.  For example, at 100 uH and 5 mF, the cutoff frequency is 225 Hz, or below the fourth harmonic.  Care must be taken not to affect or distort the 60 Hz wave form or all sorts of bad things will happen, especially to switching power supplies.

These units also need have a bypass method installed.  If one of the MOV modules needs to be replaced, power to the unit has to be secured.  This can be done by connecting it to the AC mains before any generator transfer switch.  That way, the main power can be secured and the site can run on generator power while the maintenance on the surge suppression unit is taking place.

Donate


Axiom


Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

Free counters!