{"id":9374,"date":"2017-04-30T18:48:03","date_gmt":"2017-04-30T22:48:03","guid":{"rendered":"http:\/\/www.engineeringradio.us\/blog\/?p=9374"},"modified":"2023-03-19T10:41:59","modified_gmt":"2023-03-19T14:41:59","slug":"voa-site-b-greenville-nc","status":"publish","type":"post","link":"https:\/\/www.engineeringradio.us\/blog\/2017\/04\/voa-site-b-greenville-nc\/","title":{"rendered":"VOA Site B, Greenville, NC"},"content":{"rendered":"<p>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.\u00a0 Thus, I made arrangements to visit the facility on my way home.\u00a0 Chief Engineer, Macon Dail, was gracious enough to give us the guided tour.\u00a0 The facility is an engineering marvel.\u00a0 The scale and complexity are enormous.\u00a0 The entire facility is scrupulously maintained.\u00a0 Many of the transmitters and other equipment have been upgraded to make them more functional. \u00a0 I tried to take meaningful pictures, but in many cases, they simply do not do justice.<\/p>\n<figure id=\"attachment_9381\" aria-describedby=\"caption-attachment-9381\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9381\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_site_B.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9381\" class=\"wp-caption-text\">Edward R Murrow Transmitting Facility, (VOA Greenville Site B) Grimesland, North Carolina<\/figcaption><\/figure>\n<p>Officially known as the <a href=\"https:\/\/en.wikipedia.org\/wiki\/International_Broadcasting_Bureau_Greenville_Transmitting_Station\" target=\"_blank\" rel=\"noopener noreferrer\">Edward R Murrow Transmitting Station<\/a> of the International Broadcasting Bureau, VOA Site B was constructed in 1961.\u00a0 Six of the eight shortwave transmitters are original to the construction of the building.\u00a0 The other two (BBC SK55 and AEG S4005) were added in 1986.\u00a0 All of the dipole curtain arrays, rhombics, transmission line, and antenna switching matrices are also original.\u00a0 A few brief statistics about this site:<\/p>\n<ul>\n<li>Land area is 2,715 acres (1099 hectares).<\/li>\n<li>Over twenty-six miles (forty-two kilometers) of 300-ohm open transmission line rated at 500 KW.<\/li>\n<li>Sixteen <a href=\"https:\/\/en.wikipedia.org\/wiki\/Curtain_array\" target=\"_blank\" rel=\"noopener noreferrer\">dipole curtain arrays<\/a>, average antenna gain 17 dBi.<\/li>\n<li>Twenty <a href=\"https:\/\/en.wikipedia.org\/wiki\/Rhombic_antenna\" target=\"_blank\" rel=\"noopener noreferrer\">rhombic antennas<\/a>, antenna gain 15 dBi.<\/li>\n<li>Two of the dipole curtain arrays can slew azimuth and take off angle.<\/li>\n<li>Three Continental Electronics 420A 500 KW <a href=\"https:\/\/en.wikipedia.org\/wiki\/Doherty_amplifier\" target=\"_blank\" rel=\"noopener noreferrer\">Doherty<\/a> modulated transmitters.<\/li>\n<li>Three General Electric 4BT250A1 250 KW high-level plate modulated transmitters.<\/li>\n<li>One Brown Boveri Company (BBC) SK55C3 500 KW PSM transmitter.<\/li>\n<li>One AEG Telefunken S4005 500 KW PDM transmitter.<\/li>\n<li>The antenna switch matrix connects any of the eight transmitters to any of the thirty-six antennas<\/li>\n<\/ul>\n<p>While we were there, both of the newer transmitters were on the air, running at 250 KW.\u00a0 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.<\/p>\n<p>The station staff has, out of necessity, fabricated some very cool upgrades to the transmitters and facility.\u00a0 The first of which is the alarm annunciator, which is based on a Star Trek (Original Series) sound scheme.\u00a0 Once or twice I heard the bridge general alarm go off, followed by a female voice stating the problem: &#8220;GB8, OFF AIR.&#8221;<\/p>\n<figure id=\"attachment_9405\" aria-describedby=\"caption-attachment-9405\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9405\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office-650x488.jpg\" alt=\"\" width=\"650\" height=\"488\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office-650x488.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office-150x113.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office-300x225.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office-768x576.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office-400x300.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-office.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9405\" class=\"wp-caption-text\">Chief Engineer&#8217;s office.\u00a0 NCC-1701; no bloody A, no bloody B, no bloody C, and no bloody D<\/figcaption><\/figure>\n<p>The GE 250 KW transmitters have been retrofitted with a computer-controlled auto-tune system for frequency changes.\u00a0 The antenna switch matrix controller has been replaced by a PLC-based system.\u00a0 As the transmitters are so old, many of the transmitter-specific parts need to be machined or fabricated locally.\u00a0 The rest of the transmitter parts are stocked in a large parts storage room, all of which are meticulously labeled and tracked.\u00a0 The floors are waxed and spotless, there is no dust on the horizontal surfaces, the workshop is clean, tools are put away, grass and weeds are cut, etc.\u00a0 All of these little details did not go unnoticed and indicated great pride by the staff in the facility itself.<\/p>\n<p>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.\u00a0 Arranged around that are the eight shortwave transmitters in two long transmitter galleries.<\/p>\n<figure id=\"attachment_9383\" aria-describedby=\"caption-attachment-9383\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9383\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-control-room.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9383\" class=\"wp-caption-text\">VOA Site B control room<\/figcaption><\/figure>\n<p>From this point, the operator can view all of the transmitters in the two transmitter galleries.<\/p>\n<figure id=\"attachment_9422\" aria-describedby=\"caption-attachment-9422\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9422\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops-650x488.jpg\" alt=\"\" width=\"650\" height=\"488\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops-650x488.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops-150x113.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops-300x225.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops-768x576.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops-400x300.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ops.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9422\" class=\"wp-caption-text\">Operating position<\/figcaption><\/figure>\n<p>Around the control operator are arranged a series of computer monitors showing various station function status.<\/p>\n<figure id=\"attachment_9384\" aria-describedby=\"caption-attachment-9384\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9384\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_modulation.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9384\" class=\"wp-caption-text\">Transmitter modulation and status indicators<\/figcaption><\/figure>\n<figure id=\"attachment_9385\" aria-describedby=\"caption-attachment-9385\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9385\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA_ant_status.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9385\" class=\"wp-caption-text\">Antenna Matrix status and control<\/figcaption><\/figure>\n<figure id=\"attachment_9386\" aria-describedby=\"caption-attachment-9386\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9386\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-control.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9386\" class=\"wp-caption-text\">VOA transmitter control and status (center)<\/figcaption><\/figure>\n<figure id=\"attachment_9387\" aria-describedby=\"caption-attachment-9387\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9387\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-monitor.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9387\" class=\"wp-caption-text\">Audio monitoring router<\/figcaption><\/figure>\n<p>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.<\/p>\n<figure id=\"attachment_9388\" aria-describedby=\"caption-attachment-9388\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9388\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-equipment-racks.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9388\" class=\"wp-caption-text\">Equipment racks and Shift Supervisor&#8217;s\u00a0 office<\/figcaption><\/figure>\n<figure id=\"attachment_9389\" aria-describedby=\"caption-attachment-9389\" style=\"width: 400px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9389\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-frequency-gen-400x600.jpg\" alt=\"\" width=\"400\" height=\"600\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-frequency-gen-400x600.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-frequency-gen-100x150.jpg 100w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-frequency-gen-200x300.jpg 200w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-frequency-gen-768x1152.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-frequency-gen.jpg 1000w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-9389\" class=\"wp-caption-text\">Transmitter frequency generators<\/figcaption><\/figure>\n<figure id=\"attachment_9390\" aria-describedby=\"caption-attachment-9390\" style=\"width: 400px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9390\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-rack-400x600.jpg\" alt=\"\" width=\"400\" height=\"600\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-rack-400x600.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-rack-100x150.jpg 100w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-rack-200x300.jpg 200w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-rack-768x1152.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-audio-rack.jpg 1000w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-9390\" class=\"wp-caption-text\">Audio processors, modulation monitors and patch panels<\/figcaption><\/figure>\n<figure id=\"attachment_9391\" aria-describedby=\"caption-attachment-9391\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9391\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-backup-audio.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9391\" class=\"wp-caption-text\">Backup audio feeds<\/figcaption><\/figure>\n<p>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.\u00a0 Prior to 1995, an eight-hop microwave system covering the 300-mile (483 KM) distance was used.<\/p>\n<figure id=\"attachment_9392\" aria-describedby=\"caption-attachment-9392\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9392\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GE-4BT250A.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9392\" class=\"wp-caption-text\">GE 4BT250A transmitter with computer-controlled tuning system installed<\/figcaption><\/figure>\n<p>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 microcontrollers 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.<\/p>\n<figure id=\"attachment_9393\" aria-describedby=\"caption-attachment-9393\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9393\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1-650x488.jpg\" alt=\"\" width=\"650\" height=\"488\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1-650x488.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1-150x113.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1-300x225.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1-768x576.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1-400x300.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A1.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9393\" class=\"wp-caption-text\">GE 4BT250A transmitter<\/figcaption><\/figure>\n<figure id=\"attachment_9394\" aria-describedby=\"caption-attachment-9394\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9394\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2-650x488.jpg\" alt=\"\" width=\"650\" height=\"488\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2-650x488.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2-150x113.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2-300x225.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2-768x576.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2-400x300.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A2.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9394\" class=\"wp-caption-text\">Your humble author and CE Macon Dail discussing the auto-tune system<\/figcaption><\/figure>\n<figure id=\"attachment_9395\" aria-describedby=\"caption-attachment-9395\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9395\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A3.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9395\" class=\"wp-caption-text\">GE 4BT250A auto-tune modification<\/figcaption><\/figure>\n<figure id=\"attachment_9396\" aria-describedby=\"caption-attachment-9396\" style=\"width: 400px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9396\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A4-400x600.jpg\" alt=\"\" width=\"400\" height=\"600\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A4-400x600.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A4-100x150.jpg 100w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A4-200x300.jpg 200w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A4-768x1152.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-4BT250A4.jpg 1000w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-9396\" class=\"wp-caption-text\">GE 4BT250A IPA tube and input tuning.<\/figcaption><\/figure>\n<p>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<\/p>\n<figure id=\"attachment_9398\" aria-describedby=\"caption-attachment-9398\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9398\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-BT250A5.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9398\" class=\"wp-caption-text\">GE 4BT250A transformer vault<\/figcaption><\/figure>\n<p>The GE transmitter transformers still contain PCBs. The plate transformers are in the back, basically pole transformers, one for each phase. Primary voltages are 4,180 volts, and secondary rectified voltages are 12 KVDC (PA plate supply) \u00a0and 15 KVDC (modulator plate supply).<\/p>\n<figure id=\"attachment_9399\" aria-describedby=\"caption-attachment-9399\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9399\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-behind-GE.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9399\" class=\"wp-caption-text\">Hallway and maintenance access to back of GE transmitters<\/figcaption><\/figure>\n<figure id=\"attachment_9400\" aria-describedby=\"caption-attachment-9400\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9400\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-AEG_S4005.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9400\" class=\"wp-caption-text\">AEG Telefunken S4005 500 KW transmitter on the air<\/figcaption><\/figure>\n<p>While we were there, the newer transmitters were in operation transmitting Spanish language programming to Cuba on 13,605 KHz and 11,930 KHz.\u00a0 Currently, the Greenville site is broadcasting mostly Spanish language programming with some English, French, and Bambara language programming for Africa.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-large wp-image-9424\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS-650x488.jpg\" alt=\"\" width=\"650\" height=\"488\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS-650x488.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS-150x113.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS-300x225.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS-768x576.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS-400x300.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-GS.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><\/p>\n<p>A fact that does not escape the notice of the staff.<\/p>\n<figure id=\"attachment_9401\" aria-describedby=\"caption-attachment-9401\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9401\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-transmitters-8-3.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9401\" class=\"wp-caption-text\">VOA transmitter gallery, showing transmitters GB8 through GB4<\/figcaption><\/figure>\n<figure id=\"attachment_9403\" aria-describedby=\"caption-attachment-9403\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9403\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-420A.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9403\" class=\"wp-caption-text\">Continental Electronics 420A 500 KW Shortwave transmitter control and metering panel<\/figcaption><\/figure>\n<p>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.<\/p>\n<figure id=\"attachment_9404\" aria-describedby=\"caption-attachment-9404\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9404\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-electrical-distribution.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9404\" class=\"wp-caption-text\">Electrical distribution panel<\/figcaption><\/figure>\n<p>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 setup is no mean feat. The pictures I took of the antenna matrix building do not show the size and complexity of the system.<\/p>\n<figure id=\"attachment_9408\" aria-describedby=\"caption-attachment-9408\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9408\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-trans-line.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9408\" class=\"wp-caption-text\">Transmission line between transmitter building and antenna matrix building<\/figcaption><\/figure>\n<p>For that, we need a satellite photo:<\/p>\n<figure id=\"attachment_9407\" aria-describedby=\"caption-attachment-9407\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9407\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix-650x405.jpg\" alt=\"\" width=\"650\" height=\"405\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix-650x405.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix-150x94.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix-300x187.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix-768x479.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix-400x249.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-ant-matrix.jpg 991w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9407\" class=\"wp-caption-text\">VOA Site B antenna matrix building<\/figcaption><\/figure>\n<p>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 ductwork), then runs all the way to the back of the building. Each antenna transmission line comes 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.<\/p>\n<figure id=\"attachment_9410\" aria-describedby=\"caption-attachment-9410\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9410\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-antenna-control.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9410\" class=\"wp-caption-text\">Custom-made antenna matrix control system<\/figcaption><\/figure>\n<figure id=\"attachment_9411\" aria-describedby=\"caption-attachment-9411\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9411\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-tx-lines.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9411\" class=\"wp-caption-text\">300-ohm open transmission lines<\/figcaption><\/figure>\n<figure id=\"attachment_9412\" aria-describedby=\"caption-attachment-9412\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9412\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-open-TX-lines-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-open-TX-lines-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-open-TX-lines.jpg 1200w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-open-TX-lines-765x510.jpg 765w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-open-TX-lines-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-open-TX-lines-768x512.jpg 768w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9412\" class=\"wp-caption-text\">300 ohm open transmission lines<\/figcaption><\/figure>\n<p>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.<\/p>\n<figure id=\"attachment_9413\" aria-describedby=\"caption-attachment-9413\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9413\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9413\" class=\"wp-caption-text\">Dipole curtain arrays<\/figcaption><\/figure>\n<p>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 antenna&#8217;s phase relationship to each other can be changed to adjust the takeoff angle and azimuth, thus giving optimum coverage to the targeted area.<\/p>\n<figure id=\"attachment_9414\" aria-describedby=\"caption-attachment-9414\" style=\"width: 400px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9414\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-detail-400x600.jpg\" alt=\"\" width=\"400\" height=\"600\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-detail-400x600.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-detail-100x150.jpg 100w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-detail-200x300.jpg 200w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-detail-768x1152.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-detail.jpg 1200w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-9414\" class=\"wp-caption-text\">Close up curtain array<\/figcaption><\/figure>\n<p>In this picture, the dipole antennas are to the right. Behind them is the reflector screen, and behind that is the antenna feed system. Each antenna feed goes through the reflector screen to the center of the dipole antenna.<\/p>\n<p>Each array requires four towers to support it.<\/p>\n<figure id=\"attachment_9415\" aria-describedby=\"caption-attachment-9415\" style=\"width: 400px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9415\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-supporting-towers-400x600.jpg\" alt=\"\" width=\"400\" height=\"600\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-supporting-towers-400x600.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-supporting-towers-100x150.jpg 100w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-supporting-towers-200x300.jpg 200w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-supporting-towers-768x1152.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-supporting-towers.jpg 1000w\" sizes=\"auto, (max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-9415\" class=\"wp-caption-text\">Curtain dipole array supporting towers<\/figcaption><\/figure>\n<figure id=\"attachment_9416\" aria-describedby=\"caption-attachment-9416\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9416\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-towers.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9416\" class=\"wp-caption-text\">Curtain dipole array supporting towers<\/figcaption><\/figure>\n<figure id=\"attachment_9418\" aria-describedby=\"caption-attachment-9418\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9418\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-atu.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9418\" class=\"wp-caption-text\">Remote Antenna Switch.\u00a0 Allows two antennas to use one transmission line.<\/figcaption><\/figure>\n<p>The entire antenna field is viewable from an observation platform on the main building<\/p>\n<figure id=\"attachment_9419\" aria-describedby=\"caption-attachment-9419\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9419\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-obs-platform.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9419\" class=\"wp-caption-text\">Observation room<\/figcaption><\/figure>\n<figure id=\"attachment_9420\" aria-describedby=\"caption-attachment-9420\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9420\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-gate.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9420\" class=\"wp-caption-text\">Entrance gate and slewable curtains in the background<\/figcaption><\/figure>\n<figure id=\"attachment_9421\" aria-describedby=\"caption-attachment-9421\" style=\"width: 650px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-9421\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-curtain-arrays1.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><figcaption id=\"caption-attachment-9421\" class=\"wp-caption-text\">Curtain arrays<\/figcaption><\/figure>\n<p>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.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-large wp-image-9426\" src=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-650x433.jpg\" alt=\"\" width=\"650\" height=\"433\" srcset=\"https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-650x433.jpg 650w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-150x100.jpg 150w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-300x200.jpg 300w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-768x512.jpg 768w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE-400x267.jpg 400w, https:\/\/www.engineeringradio.us\/blog\/wp-content\/uploads\/2017\/04\/VOA-CE.jpg 1200w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><\/p>\n<p>Special thanks to Macon Dail for his time, knowledge, and patience.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>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.\u00a0 Thus, I made arrangements to visit the facility on my way home.\u00a0 &hellip; <a href=\"https:\/\/www.engineeringradio.us\/blog\/2017\/04\/voa-site-b-greenville-nc\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">VOA Site B, Greenville, NC<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[32,231,50,283],"class_list":["post-9374","post","type-post","status-publish","format-standard","hentry","category-tech-stuff","tag-am-transmitters","tag-hf","tag-shortwave","tag-voa"],"_links":{"self":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/9374","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/comments?post=9374"}],"version-history":[{"count":21,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/9374\/revisions"}],"predecessor-version":[{"id":11100,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/posts\/9374\/revisions\/11100"}],"wp:attachment":[{"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/media?parent=9374"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/categories?post=9374"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.engineeringradio.us\/blog\/wp-json\/wp\/v2\/tags?post=9374"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}