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The Energy Onix Pulsar transmitter

Engineering Radio: The Oh Dear God Edition.

I have been tasked with fixing one of these glorious contraptions. Aside from the usual Energy Onix quirks; design changes not reflected in the schematic diagram and a company that no longer exists, it seems to fairly simply machine. Unfortunately, it has spent its life in less than ideal operating conditions.

Energy Onix Pulsar 1000 in the wild. Excuse the potato quality photo

Energy Onix Pulsar 1000 in the wild. Excuse the potato quality photo

Upon arrival, it was dead in the water.  Found copious mouse droppings, dirt and other detritus within and without of the transmitter.  Repaired the broken start/stop switches, fixed the RF drive detector, replaced the power supply capacitors and now at least the unit runs.  The problem now is the power control is unstable.  The unit comes up at full power when it first switched on, then it drops back to 40 watts, then after it warms up more goes to about 400 watts and the audio sounds distorted.  This all points towards some type of thermal issue with one of the power control op amps or other composite device.

After studying the not always accurate schematic diagrams, the source of the problem seems to be carrier level control circuit.  This is based around a Fairchild RC4200AN (U10 on the Audio/PDM driver board) which is an analog multiplier chip.   That chip sets the level of the PDM audio output which is fed into the PDM integrator circuit.  Of course, that chip is no longer manufactured.  I can order one from China on eBay and perhaps that will work out okay.  This all brings to mind the life cycle of solid state components.  One problem with the new technology; most solid state components have a short production life, especially things like multiplier chips.  Transmitters are generally expected to last 15-20 years in primary service.  Thus, transmitter manufactures need to use chips that will not become obsolete (good luck with that), or purchase and maintain a large stock of spare parts.

In the mean time, the chip is on its way from China.  Truth be told, this fellow would be better off with a new transmitter.

Decommissioning transmitters

I was at a transmitter site a few days ago scrapping a Continental 814-R1 transmitter and started thinking (always a dangerous thing) about how many of these units I have decommissioned over the years.  It turns out, quite a few:

Make/Model Year new* Year removed Station Disposition
GE BT25A 1948 1994 WPTR Donated/scrapped
Gates BC5P 1960 2004 WWLO Donated
Harris MW5A 1982 2000 WLNA Scrapped
Gates BC1T 1961 2001 WLNA Donated
Harris FM20H3 1972 2001 WYJB Scrapped
RCA BT1AR 1960 2001 WROW Donated
Harris BC1G 1972 2001 WDFL Abandoned
Harris FM20H3 1971 2005 WHUD Scrapped
BE FM30A 1988 2005 WHUD Cannibalized
Harris FM5G 1972 2008 WSPK Scrapped
Mc Martin BF3.5K 1976 2011 WCTW Scrapped
RCA BTF-10ES 1978 2011 WRKI Scrapped
Gates BC1T 1964 2011 WINE Scrapped
Continental 315F-R1 1985 2013 WVMT Donated
Collins 813F 1975 2014 WKXZ Scrapped
RCA BTA1AR 1965 2014 WCHN Scrapped
Collins 813F2 1978 2015 WKXZ Scrapped
Collins 830D-1A 1968 2014 WKXZ Scrapped
Harris FM20H3 1972 2013 WYJB Scrapped
Harris BC5HA 1973 2013 WROW Scrapped
Harris FM10H 1971 2013 WMHT-FM Scrapped
Harris FM2.5H3 1973 2015 WEXT Scrapped
Mc Martin BF3.5K 1972 2014 WSRK Scrapped
CCA FM5000G 1980 2015 WTBD Scrapped
RCA BTF1E 1972 2016 WZOZ Scrapped
QEI 695T3.5 1996 2015 WBPM Scrapped
QEI 695T5 1996 2015 WBPM Scrapped
Harris HT3.5 1997 2015 WUPE-FM Scrapped
Harris Z5CD 1997 2015 WXPK Cannibalized
Energy Onix SSA1000 2000 2015 WDHI Cannibalized
Harris MW1 1982 2016 WPUT Abandoned
Mc Martin BF1K 1982 2016 WSUL Scrapped
Mc Martin BF3.5K 1982 2016 WSUL Scrapped
Continental 814R1 1980 2016 WDBY Scrapped

*In some cases the “Year New” is a guess based on when the station went on the air.  Before you write me and say “But model XYZ transmitter wasn’t made until 19XX, I did not look at every name plate and write all the information down as I did this.

Like everything else, there is a process to this.

RCA BTA-10U AM transmitter

RCA BTA-10U AM transmitter

First of all, if the transmitter was made before 1978, the possibility of PCB capacitors and transformers exists. In the case of the GE BT25A, massive amounts of PCBs needed to be disposed of properly. According to current federal laws, ownership of PCBs and PCB contaminated items cannot be transferred. Thus, the transformer casings were cleaned out and taken to Buffalo to be buried in a PCB certified landfill.   Otherwise, most other transmitters, such as the RCA BTA-10, may have a few PCB capacitors in them and perhaps the modulation transformer.  Those items can be disposed of by calling an authorized environmental disposal company like Clean Harbors.

The rest of the transmitter is stripped of any useful parts.  Things like vacuum variable capacitors, rectifier stacks, blower motors (if they are in good condition), HV power supply contactors, unique tuning parts, whole control and metering boards, tube sockets, etc.

The remaining carcase is then disassembled and hauled off.  I got a guy that will do this for relatively little money.  He takes the transmitter back to his warehouse and cuts it up, sorts all of the various metals out, then takes it to the scrap yard.  This includes things like cutting all of the windings off of transformers and power supply chokes, sorting out the brass and copper tuning parts, etc.

Village seeks repayment from Energy Onix

This saddens me a little bit.  Apparently, the Village of Valatie, NY is seeking repayment of a $500K loan from Transmitter Manufacturer Energy Onix.  Since the passing of Bernie Wise, the company has basically folded.

The village may foreclose on the building if necessary, said Mayor Diane Argyle.

Located at 1306 River St., Energy-Onix was founded in 1987 by broadcast pioneer Bernard Wise, who is known for bringing the “grounded grid” to radio broadcasting. The company designed, manufactured and sold radio transmitters and tubes.

More from the Columbia-Greene Register Star.

Sadly, there goes support for many Energy Onix and CCA transmitter still in the field.  I know of several of those old CCA transmitters that are still cranking away, 40 or more years after they rolled out of the factory in Gloucester, NJ.   I have tried, several times, to call Energy Onix since Bernie passed last year and the phone goes unanswered.  I wonder if we could pick up the the field support and service for these units.  I wonder if there are any spare parts left at the old factory building?

 

 

Broadbanding an AM antenna

Many articles have been written on the topic and it is still a black art to some.  Making a Medium Frequency (MF) antenna that has enough bandwidth to pass 10 KHz audio can be challenging, to say the least.  The VSWR out to +/- 15 KHz carrier needs to be kept at a minimum and the power needs to be evenly distributed between the two sidebands.  This can become problematic with complex Directional Arrays or towers that are tall or short for their operating frequency.

When we were working on the WFAS-AM tower in White Plains, NY, it became apparent to me that something was not right.  The tower is skirted and now holds the antenna for W232AL, a 250 watt translator broadcasting the WPLJ HD-2 channel.  After installing the FM antenna, some tuning of the AM antenna was required and this is the graph of the resistance and reactance curves:

WFAS 1230 KHZ, ATU output resistance and reactance

WFAS 1230 KHZ, ATU output resistance and reactance

This looked very similar to the resistance and reactance curves before the FM antenna work was done.  Red line is resistance, the blue line is reactance.  I think it had been like this for a long time.  While it is not terrible, it is not that good either.  As alluded to in a previous post, some re-working of the ATU was needed.  After some trial and error, this is the circuit that we ended up with:

WFAS 1230 KHZ White Plains, NY ATU schematic

WFAS 1230 KHZ White Plains, NY ATU schematic

Not quite what I expected, however, it was designed with the parts on hand, excepting the vacuum variable output capacitor, which was donated by me.  That part was key in making the proper adjustments.

After my redesign and tune up of the ATU, this the resistance and reactance curves at the input terminal of the ATU:

WFAS 1230 KHz resistance and reactance after ATU modification

WFAS 1230 KHz resistance and reactance after ATU modification

The graphs have a slightly different format, but you get the idea.  The red line is resistance, the blue line is reactance and the green line is overall impedance.  The resistance is symmetrical about the carrier as is the reactance.  Truth be told, I think there is a little more that can be had here, but for now, there is no reason to go any further.  I made the initial measurements at the input of the ATU and confirmed them again at the output terminals of the transmitter.  When we turned the transmitter back on, I noticed that the modulation index had dropped by about 15 percent.  I think the reflected power was getting back into the RF sample and fooling the mod monitor.  I also noticed that the high end in particular sounded much nicer.

WFAS 1230 KHz, White Plains, NY ATU

WFAS 1230 KHz, White Plains, NY ATU

The ATU building is a little cramped and it is hard to get a good picture.  The vacuum variable capacitors were salvaged from a scrapped AM transmitter years ago.  The tower is 202 degrees tall, which is also a factor.  It will be interesting to see what seasonal changes there are with snow cover, mud, etc.

Overall, this was a fun project.

Transmitter repair

Sometimes it is obvious and relatively easy, other times not so much.  This summer we have had wave after wave of afternoon thunderstorms.  It is almost like living in Florida; almost, but not quite.  Anyway, with the storms occasionally comes some lightning damage.  At most of the transmitter sites we service, every step has been taken to ensure good grounding and adequate surge suppression.  This is especially true of sites that have been under our care for a few years.  Even so, occasionally, something gets through.  After all, those five hundred foot steel towers do attract lightning.

Broadcast Electronics AM5E output tuning section

Broadcast Electronics AM5E output tuning section

This is the output section of the BE AM5E transmitter at WROW.  The transmitter got pretty trashed; a bad PA module and power supply and this capacitor in the output section.  This particular transmitter is 14 years old and this is the first major repair work we’ve had to do it.

Broadcast Electronics AM5E output tuning capacitor

Broadcast Electronics AM5E output tuning capacitor

The capacitor was fairly easy to change out.  As a general precaution, both capacitors were changed.  There was a spare PA module and power supply on the shelf, thus the transmitter was returned to full power relatively quickly.

Broadcast Electronics AM5E output forward and reflected power meters

Broadcast Electronics AM5E output forward and reflected power meters

The rest of the antenna system and phasor were inspected for damage, a set of common point impedance measurements taken, which showed that no other damage was sustained.

Next, the 30 year old Harris SX2.5 A transmitter at WSBS.  This failure was slightly more exotic; the transmitter started randomly turning itself off.  The culprit in that case was this:

Harris SX2.5 remote control interface bypass capacitor

Harris SX2.5 remote control interface bypass capacitor

Literally, a two cent part.  The transmitter remote control uses opto-isolators.  The inputs to these opto-isolators are RF bypassed to ground on the back of the “customer interface board.”  After determining that the remote control was not malfunctioning, it was down to either a bad opto-isolator or something really silly like a bypass capacitor.  This capacitor was on the ground side of the remote off terminal.  It shows short on the capacitance meter and 4.1 K on the ohm meter, just enough to randomly turn the opto-isolator on and shut down the transmitter.  Being a Harris transmitter, removing and replacing the “customer interface board” was no easy matter.  Overall, it took about three hours to find and repair this problem.

Engineer Killer

That was the title of the email with this photo attached:

Disabled high voltage shorting bar, Collins 820D-2

Disabled high voltage shorting bar, Collins 820D-2 AM transmitter.  Courtesy Pete Partinio

Seems about right.

For many, many reasons, this is a bad thing to do.  First of all, that shorting bar is the last point of discharge for the high voltage power supply.  When all else fails, this is designed to route the 3,500 volt plate supply safely to ground.  Having a stray 3,500 volts floating around inside of a transmitter is never a good idea.  Fortunately, it was spotted and removed before anything bad happened.

Secondly, it looks like somebody used a 12 VDC cigarette lighter plug as an insulating device.  Wow, did they get lucky.  This could have started a fire.

As to exactly why it was there in the first place, I cannot rightly say.

And this is why only properly trained people should be working on transmitter, especially tube type transmitters.

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.

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.

A day in Pictures

The aftermath:

Long beach

Long beach, this used to be an isthums, now it is a sand bar

A set of old stairs

A set of old stairs on the beach where the cottages used to be located.

Surf

Surf

100 lb propane tanks

Found the reason why the generator is not running

Propane tanks adrift

Propane tanks adrift from storm surge. There was a strong propane smell around these tanks, I secured all the valves.

WICC propane tank pad

Where the propane tanks should be

debris washed ashore during storm surge

Debris washed ashore during storm surge around north tower, including a section of dock

Second high tide after Hurricane Sandy, noon on Tuesday

Second high tide after Hurricane Sandy, noon on Tuesday, flooding ground system

three phase power line down

Three phase power line down due to wind

Three phase power line down

More wind damaged power lines

Telco wires taken down by trees

Telco wires taken down by trees

Generator room water level, as seen on the side of the battery

Generator room water level, as seen on the side of the battery

More work here tomorrow.

Update: Took longer than anticipated, but the station is back on the air with generator power as of 8:15 am, Thursday (11/1).  Commercial power restoration is not expected until Monday or Tuesday at the earliest.

Update: Commercial power restored on Thursday, 11/8 for a total outage of 10 days.  One good thing about incidents like this, I now have a fresh set of contacts for all the important people connected to servicing this site.

Fire! Fire! Fire!

Class Charlie fire in the transmitter room electrical panel.  Away fire party from repair locker forward.  Set condition ZEBRA throughout the ship, this is not a drill.

Or something like that.  If you were driving around Albany, NY this afternoon and noticed WDCD-FM was off the air, this is the reason why.

WDCD AM/FM main distribution panel

WDCD AM/FM 480 volt 3 phase AC main distribution panel

A little after noon time, the 480 volt main distribution panel at WDCD AM/FM caught fire, taking the FM station off the air.

WDCD conference room clock, time of power outage noted

WDCD conference room clock, time of power outage noted

According to this clock, it happened at 12:19 pm, when there was a loud bang and the lights in the studio flickered several times, followed by the building fire alarm going off.  Thankfully, a quick response by the station staff and the Town of Colonie fire department limited the damage to the interior of the distribution panel.  Other than the dry chemical fire extinguisher residue all over the place, the building is none the worse for wear.

WDCD distribution panel burned parts

WDCD distribution panel burned parts

The 480 Volt three phase electrical distribution panel was installed in 1947 when the original building was constructed.  The power company cut the power to the building and an electrician was able to re-route the distribution for the dry step down transformers that power the studios and equipment racks.  The original 480 volt service was installed due to the 50 KW AM transmitter for WPTR (WDCD-AM).   Currently, WDCD-AM is silent, pending programming decisions by the owner, Crawford Broadcasting.

WDCD burned electrical distribution panel parts

WDCD burned electrical distribution panel parts

So, we spent the late afternoon vacuuming the NextGen computers and UPS out, wiping down the equipment and making sure to clean out the power supplies and other nooks and crannies.  Then, we powered everything back up, one at a time and to our pleasant surprise, all came back up without error.  Total off air time for the FM station was about 6 hours.

Axiom


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

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!