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VOA Site B, Greenville, NC

I took a brief vacation last week along the coast of North Carolina. It was relaxing and fun to be sure. I was also aware of and slightly curious about the Voice Of America shortwave site, a slight distance inland in Grimesland, NC.  Thus, I made arrangements visit the facility on my way home.  Chief Engineer, Macon Dail, was gracious enough to give us the guided tour.  The facility is an engineering marvel.  The scale and complexity is enormous.  The entire facility is scrupulously maintained.  Many of the transmitters and other equipment have been upgraded to make them more functional.   I tried to take meaningful pictures, but in many cases, they simply do not to justice.

Edward R Murrow Transmitting Facility, (VOA Greenville Site B) Grimesland, North Carolina

Officially known as the Edward R Murrow Transmitting Station of the International Broadcasting Bureau, VOA Site B was constructed in 1961.  Six of the eight shortwave transmitters are original to the construction of the building.  The other two (BBC SK55 and AEG S4005) were added in 1986.  All of the dipole curtain arrays, rhombics, transmission line and the antenna switching matrix are also original.  A few brief statistics about this site:

  • Land area is 2,715 acres (1099 hectare).
  • Over twenty six miles (forty two kilometers) of 300 ohm open transmission line rated at 500 KW.
  • Sixteen dipole curtain arrays, average antenna gain 17 dBi.
  • Twenty rhombic antennas, antenna gain 15 dBi.
  • Two of the dipole curtain arrays can slew azimuth and take off angle.
  • Three Continental Electronics 420A 500 KW Doherty modulated transmitters.
  • Three General Electric 4BT250A1 250 KW high level plate modulated transmitters.
  • One Brown Boveri Company (BBC) SK55C3 500 KW PSM transmitter.
  • One AEG Telefunken S4005 500 KW PDM transmitter.
  • Antenna switch matrix connects any of the eight transmitters to any of the thirty six antennas

While we were there, both of the newer transmitters were on the air, running at 250 KW.  The GE transmitters are used as needed and the Continentals are rarely used due to age, difficulty to tune, change frequencies and gross power inefficiency.

The station staff has, out of necessity, fabricated some very cool upgrades to the transmitters and facility.  The first of which is the alarm annunciator, which is based on a Star Trek (Original Series) sound scheme.  Once or twice I heard the bridge general alarm go off, followed by a female voice stating the problem: “GB8, OFF AIR.”

Chief Engineer’s office.  NCC-1701; no bloody A, no bloody B, no bloody C, and no bloody D

The GE 250 KW transmitters have been retrofitted with a computer controlled auto tune system for frequency changes.  The antenna switch matrix controller has been replaced by a PLC based system.  As the transmitters are so old, many of the transmitter specific parts need to be machined or fabricated locally.  The rest of the transmitter parts are stocked in a large parts storage room, all of which is meticulously labeled and tracked.  The floors are waxed and spotless, there is no dust on the horizontal surfaces, the work shop is clean, tools are put away, grass and weeds are cut, etc.  All of these little details did not go unnoticed and indicate great pride by the staff in the facility itself.

The heart of the facility is the control room which consists of four rows of equipment racks and a central operating position elevated above floor level.  Arranged around that are the eight shortwave transmitters in two long transmitter galleries.

VOA Site B control room

From this point, the operator can view all of the transmitters in the two transmitter galleries.

Operating position

Around the control operator are arranged a series of computer monitors showing various station function status.

Transmitter modulation and status indicators

Antenna Matrix status and control

VOA transmitter control and status (center)

Audio monitoring router

The equipment is installed into the equipment racks by type; one rack contains the frequency generators for each transmitter, the next contains first stage power amplifiers, the next contains audio processors and modulation monitors, etc.

Equipment racks and Shift Supervisor’s  office

Transmitter frequency generators

Audio processors, modulation monitors and patch panels

Backup audio feeds

The audio comes from the VOA studios in Washington DC via satellite. There are Comrex Access links as a backup and the Gentner EFT-1000s are used as a backup to the backup.  Prior to 1995, an eight hop microwave system covering the 300 mile (483 KM) distance was used.

GE 4BT250A transmitter with computer controlled tuning system installed

The station staff has created a computer controlled tuning system for the GE transmitters. Each transmitter can change frequency several times a day, during each frequency change, all of the transmitter stages need to be retuned. When done by hand, this can take several minutes to accomplish. The computer system uses follow pots and micro controllers to set the tuning elements to specific values. They can be touched up by hand if needed. A frequency change can usually be done in less than one minute.

GE 4BT250A transmitter

Your humble author and CE Macon Dail discussing the auto tune system

GE 4BT250A auto tune modification

GE 4BT250A IPA tube and input tuning.

The 2nd IPA and PA input tuning work the same way. The copper sleeve slides up and down over the coil to change resonant frequency. The vapor cooled tube sits inside the tub at the top, anode facing down. These tuning sections are a mechanical nightmare according to Macon. One of the reasons why VOA site A was closed down was due to the frequent frequency changes at that site causing excessive wear and tear on the old GE transmitters. This particular transmitter was being repaired; the staff was rebuilding a tuning network bypass capacitor assembly

GE 4BT250A transformer vault

The GE transmitter transformers still contain PCB’s. The plate transformers are in the back, basically pole transformers, one for each phase. Primary voltages is 4,180 volts, secondary rectified voltages are 12 KVDC (PA plate supply)  and 15 KVDC (modulator plate supply).

Hallway and maintenance access to back of GE transmitters

AEG Telefunken S4005 500 KW transmitter on the air

While we were there, the newer transmitters were in operation transmitting Spanish language programming to the Cuba on 13,605 KHz and 11,930 KHz.  Currently, the Greenville site is broadcasting mostly Spanish language programming with some English, French and Bambara language programming for Africa.

A fact that does not escape the notice of the staff.

VOA transmitter gallery, showing transmitters GB8 through GB4

Continental Electronics 420A 500 KW Shortwave transmitter control and metering panel

The three Continental 420A transmitters (GB-1, GB-2 and GB-3) are essentially a pair of 250 KW amplifiers combined. As these are Doherty power amplifiers, frequency changes are very difficult to effect. These transmitters spend most of their time in backup service.

Electrical distribution panel

The antenna matrix building is very impressive. Routing eight 250 or 500 KW transmitters to 36 different antennas takes a bit of doing. Mechanizing that set up is no mean feat. The pictures I took of the antenna matrix building do not show the size and complexity of the system.

Transmission line between transmitter building and antenna matrix building

For that, we need a satellite photo:

VOA Site B antenna matrix building

Basically, the transmitter building is in the lower left hand side of the picture. The transmission line go over to the antenna matrix building (looks like rectangular duct work), then run all the way to the back of the building. Each antenna transmission line come into the building and runs to the other side. Pneumatic arms then couple the transmitter line to the antenna line. This is all controlled by a custom made PLC and controlled by the operator from the main operating desk.

Custom made antenna matrix control system

300 ohm open transmission lines

300 ohm open transmission lines

Some of these lines are very long but have low loss due to the air dielectric. The most used antennas are the dipole curtain arrays.

Dipole curtain arrays

These consist of a series of broadband dipole antennas arranged side by side and stacked three or four high. behind those antennas is a reflector screen. There are two curtain arrays that are slewable. The dipole antennas phase relationship to each other can be changed to adjust the take off angle and azimuth, thus giving optimum coverage to the targeted area.

Close up curtain array

In this picture, the dipole antennas are to the right. Behind them is the reflector screen, behind that is the antenna feed system. Each antenna feed goes through the reflector screen to the center of the dipole antenna.

Each array requires four towers to support it.

Curtain dipole array supporting towers

Curtain dipole array supporting towers

Remote Antenna Switch.  Allows two antennas to use one transmission line.

The entire antenna field is viewable from an observation platform on the main building

Observation room

Entrance gate and slewable curtains in background

Curtain arrays

The entire facility is very impressive. The truth is, I could have spent several more hours there, but I know that people have jobs to do and I felt that I had taken up enough time. We often forget in this country that not everyone in the world has access to the internet. Shortwave broadcasting has a long reach and is not subject to government controlled firewalls or other forms of electronic censorship. Currently, the Greenville site is broadcasting mostly Spanish language programming with some English language programming for Africa. There are many areas in the world that are in political tension right now, some startlingly close to home. Places like Brazil, Argentina and Venezuela have been in the news lately. I do not see a time when these long reach broadcasting services will not be needed. Becoming a welcome source of good information for those affected people is good for brand USA. It would be money well spent to invest in a couple of new Continental 419H (still made in the USA) DRM capable transmitters for this facility. While the old GE and Continental units are great, the time may come when they are really needed but unavailable due to being down for repair.

Special thanks to Macon Dail for his time, knowledge and patience.

Night of nights, 2015

Every year, the Maritime Radio Historical Society celebrates the closing of the last commercial Morse code radio station, which happened at 0001 UTC, July 13, 1999.  They do this by re-manning the watch for a few hours in honor of all those who so diligently listened for distress signals on 500 KHz and other frequencies continuously for over 90 years.  Your humble author was one of those, who in the late 1980’s and early 1990’s strained to hear, through the static crashes and OTHR, the simple, yet effective combination of SOS sent in Morse code.

Fortunately, after the closure of KPH, the National Parks Service took over the land and preserved the buildings and antenna fields intact.  Today, a dedicated group of volunteers maintain these facilities as a working museum.  This is the earliest history of radio technology and from this, sprang Amateur Radio, then Broadcast Radio services.

So, if you have the opportunity on July 12 (Sunday, starting at 8 pm, EDT), tune around to some of the frequencies listed below and see how ship to shore communications was handled:

KPH KFS KSM WLO KLB NMC NMW Ship transmit
426 426 488 472 448 425, 454, 468,480,512
500 500 500 500 500 500
2055.5
4247 4343 4184
6477.5 6383 6276
8642 8438.3 8658 8582.5 8574 8368
12808.5 12695.5 12993 12992 12552
17016.8 17026 16914 16968.5 17220.5 16736
22477 22280.5

These are duplex frequencies, meaning; the ship transmits on one frequency and listens on to the shore station on another and vice versa.

Those medium frequencies do not carry that far during daylight, however the high frequencies should be heard across the world.

In addition to that, there are youtube videos to watch:

There are more videos on youtube, if one is so inclined.

Those old RCA transmitter look like they are in excellent condition. Somebody has spent a lot of time restoring those units.

Hopefully, one of these years, I will get a chance to head out to San Fransisco during the middle of July and see this in person. It would be nice for my children to see what their old man used to do in what seems like a different lifetime.

Something fun

So, I spent wasted several hours on this SDR website over the holiday weekend:

University of Twente SDR website

University of Twente SDR website

This is a web based SDR hosted by the University of Twente in Enschede, Netherlands. I enjoyed listening to the European medium wave and shortwave stations available.  Something that is always fun to checkout: UVB-76 on 4625 KHz.

Have fun!

PS: A special thanks to all those who have donated to the cause via the donate button on the upper right side bar.  I had enough money to buy a FUNcube dongle SDR.  I think I have all the other necessary hardware to launch one of these sites myself.  If or when that happens, I will post a link here.

Those Shortwave Sites

How is our Alaska doing?

How is our Alaska doing?

It is a joke in circulating in Russia at the moment.  Kind of funny when you think about it.

In light of the developing situation in Eastern Europe, it may be wise to retain some of those HF broadcasting (AKA Shortwave) sites.  It may be too late for Canada, however, the US government still has a few high powered HF sites that they may want to hold onto for a while.  There are several ways that shortwave broadcasting can be beneficial.

  • Like all radio broadcasting, quality content is needed to attract listeners. Most of what is available on shortwave is religious or transparent government propaganda. There are exceptions to this, but they are rare. Introduce quality programming, and shortwave listenership will increase.
  • DRM 30 (Digital Radio Mondial) is still in its experimental phase.  It has been demonstrated to work reasonably well on HF.  Several digital data formats are successfully being used on HF; HFDL, ALE, STANAG 5066, PACTOR and others.  DRM 30 has an advantage that H.264 video can also be transmitted.
  • The VOA has been experimenting with images transmitted via MFSK, AKA the “VOA Radiogram.”
  • HF is always susceptible to changing propagation.  However, it can be reliable enough, especially when frequency diversity is employed, to overcome these issues when no other method of communication is available.
  • DRM and MFSK can be decoded using a simple shortwave radio and a computer sound card.  A DRM CODEC is required, but those are readily available for download.
  • Analog shortwave broadcasting using AM is still viable.  AM has the advantage of being extremely simple to receive and demodulate.  Simple receiver kits can be built and run on 9 volt a battery.
  • While the Soviet Union had an extensive jamming network, those sites have long since been non-functional.  Most countries have discontinued the practice of jamming with the exception of China, North Korea, Cuba and perhaps some countries in the middle east (the usual suspects).

Sample of DRM reception via shortwave:

If the internet is censored or somehow becomes unavailable in that part of the world,  shortwave may be the only method to convey an alternate point of view.

Hopefully, things will settle down and return to at least a civil discourse.  However, it never hurts to have a plan.

Horby and Solvesborgs transmitter site

This is a video of Radio Sweden’s shortwave and medium wave transmitter sites:

Håkan Widenstedt at Hörby and Sölvesborgs Transmitter sites from HamSphere on Vimeo.

This was filmed in 2006. In 2010, Radio Sweden ceased broadcasting on medium and shortwave, thus I believe these sites have Horby (HF) has been dismantled.  Medium wave installation Solvesborg is visible starting at 15:30. Two tower directional array 180 degree towers with 600 KW carrier power. Quite impressive.

There is an effort to at save the Solvesborg site, perhaps as a museum.

Transmitters were in Skane, Sweden:


View Larger Map

h/t Shortwave Central

Voice of Russia to cut shortwave

Another government shortwave broadcaster calls it quits.  The Voice of Russia (Голос России, Golos Rossii) will cut its shortwave service as of January 1st, 2014. Originally known as Radio Moscow, it has been on the air continuously since 1922. It will be sad to see yet another shortwave station pull the plug.

Radio Moscow stamp, courtesy of Wikimedia

Radio Moscow stamp, courtesy of Wikimedia

I can remember Radio Moscow being one the first shortwave stations I tuned across on my Uncle’s Zenith Transoceanic shortwave radio.  It was fascinating to me to hear the news from the far away and all too scary Soviet Union.  After a short bit of interval music and a series of beeps counting down to the top of the hour, a man with a deep, sonorous voice came on and said “Zis is Moscow…” It was very dramatic.

The economics of HF broadcasting are daunting to say the least.  Minimum power levels in the US are 50,000 watts into a highly directional, high gain antenna.  Most stations use greater than 50 KW transmitters, which will very quickly use gobs of electricity, becoming an expensive operation.  Other expense include maintenance on transmitters, buildings, land and antennas.  With little or no opportunity to commercialize, it becomes difficult to justify a shortwave operation.  Sadly, those are the state of affairs in HF broadcasting today.

WYFR shortwave signing off

Family Radio’s WYFR shortwave service will be ending on June 30, 2013.

WYFR 50 years

WYFR 50 years

Shortwave transmitting is very expensive, and no doubt, competing IP distribution technology and diminishing returns on such investment must play a factor in this decision.  Family radio has been struggling ever since the world did not end as predicted in 2011.

I believe that site has fourteen 100KW HF transmitters and eighteen antennas of various type.  There is a complete photo album here: https://picasaweb.google.com/115519153277489147905/WYFR?noredirect=1#5149450014785168130 courtesy of Kent.

Kind of sad to see them go, I don’t know what their plans are after June 30.

Suppression of ideas

I found this video called Empire of Noise about broadcast radio jamming. It seems to be about ten years old and is a post cold war documentary about the jamming of radio signals by the USSR, Warsaw Pact counties and China.  It is an interesting look into the extent and expense that governments will go to to suppress counter thought and ideas.

The video is quite long, and there are stretches of jamming noise that can be annoying, but perhaps that is the point.  It is worth the time if interested in history and radio broadcasting.  You know what they say about history; those that do not understand history are destined to repeat it.

A few of the highlights:

  • The former Soviet Union had the most extensive jamming network of anyone on Earth.  There were groundwave jamming centers in eighty one Soviet cities which consisted of approximately 10-15 transmitters each in the 5 KW covering the medium and shortwave frequencies.
  • Each groundwave jamming station consisted of a transmitter site and a receiver/control site.  The receiver site possessed lists of frequencies to monitor, when objectionable material was heard, the jamming transmitters were turned on.
  • There was a skywave jamming network consisting of 13 jamming stations with 10 or more 100-200 KW transmitter in each.  There were some transmitters in the 1,000 KW power range.  These were located in Krasnodar, Lvov, Nikolaev, Yerevan, Alma-Ata, Grigoriopol, Sovieck, Novosibrisk, Tashkent, Khanbarovsk, Servdlosk and Moscow (some of these names may have changed).  These operated in a similar fashion to the groundwave jammers.
  • After sign off of government stations, Soviet jammers sent a blanketing signal on the IF frequency (most likely 455 KHz) of receivers to effectively block them from receiving any station while USSR government stations were off the air.
  • Baltic states had 11 jamming stations with approximately 140 transmitters
  • Ukraine had approximately 300 Jamming transmitter.
  • Warsaw Pact countries had extensive medium frequency jamming networks.
  • It is estimated it takes about 20 times the transmitted power to jam any one signal.

The entire jamming network was hugely expensive to equip and operate, costing several tens of millions of dollars per year.

It is interesting that the US position in all of this was:

Everyone has the right to seek, receive and impart information through any media and regardless of frontiers.   Jamming of radio broadcasts is condemned as the denial of the right of persons to be fully informed concerning news, opinions and ideas.

Sounds perfectly reasonable.  The free exchange of ideas and information over the internet is something that should be guarded carefully and should not be restricted or censored.  Perhaps somebody should inform congress.

Restoration work on an RCA transmitter

I read through this article about the ongoing restoration work of an RCA SSB T-3 transmitter and found it interesting.  The RCA T-3 transmitter is a 20 KW SSB/ISB HF (2-28 MHz) unit designed for point to point telephony service.  Because SSB requires class A or AB low distortion amplifiers, this is a large unit, even for its age and power levels.

From the looks of the before pictures, this transmitter was in sorry shape.

Here is a brief video of transmitter start up:

These units were designed to be switched on and run at 100% duty cycle from most of their operating lives. That is some heavy iron there.  This particular unit was made in 1959. More here and video part 2:

Anyway, before geosynchronous satellites, HF point to point transmitters were used to make long distance phone call connections and send data and pictures back and forth over long distances. Out in Hicksville, Long Island, Press Wireless ran a data and fax system that used HF for long haul data transmission.  Much of the WWII reporting from Europe and the Pacific Theaters was carried over this system.

Text would be printed out on a mechanical teletype machine at something like 60 words per minute, which was considered fast for the time:

Tuning across the band, one can often hear Radio Teletype (RTTY or RATT) which uses a 5 bit baudot code, 170 Hz shift with 2125 HZ representing a Mark or 1 bit and 2295 Hz representing a Space or 0 bit, which is bit different from the Bell 103 modem specifications. This is what it sounds like at 75 Baud:

So slow you can almost copy that by hand.

The RCA H (SSB T-3) unit above was independent side band (ISB), which means that either side band or both could be modulated independently of the other, thus two channels of information could be transmitted.  SSB bandwidth is about 2.7 KHz, which is good for telephone grade audio or low speed data.

I sort of wish I was living in California again, I’d lend a hand.

HF broadcasting station maintenance

This video shows some of the maintenance required for a HF (AKA Shortwave) broadcast station. It starts with transmission line tensioning, some shots of a curtain array then goes on to show the inside of a transmitter building. Transmitters shown are Harris HF-100 (a 1980’s model tube type PDM design) and Continental 418, but I didn’t see the letter number. They are likely tube modulated units.

These are from the international service of Australia Broadcasting Corporation (ABC), or Radio Australia International.

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

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