{"id":45547,"date":"2020-09-26T07:22:55","date_gmt":"2020-09-26T11:22:55","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=45547"},"modified":"2020-09-26T07:23:25","modified_gmt":"2020-09-26T11:23:25","slug":"gary-debock-experiments-with-fsl-antenna-nulling-to-eliminate-a-pest-station","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2020\/09\/gary-debock-experiments-with-fsl-antenna-nulling-to-eliminate-a-pest-station\/","title":{"rendered":"Gary DeBock experiments with FSL antenna nulling to eliminate a “pest” station"},"content":{"rendered":"

Many thanks to SWLing Post contributor and Ultralight DX enthusiast, Gary DeBock, for sharing the following guest post:<\/em><\/strong><\/p>\n

\"\"<\/a>Nulling a local pest with dual FSL Loops<\/h1>\n

by Gary DeBock<\/p>\n

After many dual FSL antenna experiments I’ve finally determined how to effectively cancel out QRM from a local pest that is off to the side (ideally 90 degrees different, but practical from 50 degrees to 90 degrees different) from a weak DX station, although I’m not quite sure of the theory behind this discovery.<\/p>\n

This experiment was an attempt to cancel out QRM from a local pest, 950-KJR in Seattle, WA (35 miles\/ 56 km to the north) and chase 950-KKSE in Parker, CO (1005 miles\/ 1617 km to the southeast) during the early morning hours. The receiver was a basic (non-SSB) C.Crane Skywave<\/a>, and two identical 5 inch ferrite rod FSL antennas were used. Please refer to the photo (above) to follow this description.<\/p>\n

Step 1)<\/strong> Null out the pest station with the portable radio’s loopstick (away from the FSL antennas). Set the radio down in this nulled position, so that the pest station is as weak as possible, while ensuring that there is space to set up the FSL antennas to the back and side (see photo).<\/p>\n

Step 2)<\/strong> Take the “Reception FSL” and use it to peak the pest station’s frequency, setting it up parallel to the portable radio as shown, at the position providing the maximum inductive coupling gain. This will temporarily boost up the pest station, which previously was nulled.<\/p>\n

Step 3)<\/strong> Take the “Nulling FSL” and pretune the frequency to that of the pest station. You can do this either by adjusting the variable cap plates to match those of the “Reception FSL,” or by temporarily peaking the pest station’s signal in a position in front of the portable radio. After setting this frequency, set the “Nulling FSL” off to the side of the portable radio as shown, with the spacing identical to the spacing between the radio and the “Reception FSL.”<\/p>\n

Step 4)<\/strong> Slowly and carefully tune the “Nulling FSL” until you hear the pest station’s signal take a sharp drop. This setting will be very sharp, but once you find this position you will have nulled out the pest very effectively, and if another station is on the frequency, it may suddenly become dominant, even if it is far away (like 950-KKSE in Denver).<\/p>\n

Some MP3’s from this morning’s experiments:<\/p>\n

950-KJR in nulled position with the portable only<\/p>\nhttps:\/\/swling.com\/blog\/wp-content\/uploads\/2020\/09\/950-KJR-nulled-by-portable-092320.mp3<\/a><\/audio>\n

950-KKSE generally dominant over the local pest KJR when the “Nulling FSL” is peaked<\/p>\nhttps:\/\/swling.com\/blog\/wp-content\/uploads\/2020\/09\/950-KKSE-KJR-092320.mp3<\/a><\/audio>\n

\n

Fascinating, Gary! I don’t understand the dynamics of why this works, but it’s amazing that it does so effectively. I can think of two MW frequencies in particular where I could put a system like this to the test.\u00a0<\/strong><\/em><\/p>\n

Thank you for sharing!<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Many thanks to SWLing Post contributor and Ultralight DX enthusiast, Gary DeBock, for sharing the following guest post: Nulling a local pest with dual FSL Loops by Gary DeBock After many dual FSL antenna experiments I’ve finally determined how to effectively cancel out QRM from a local pest that is off to the side (ideally […]<\/p>\n","protected":false},"author":15,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[3607,433,3,26,3727],"tags":[1031,5767,6018,4661,3732,5820,5648],"class_list":["post-45547","post","type-post","status-publish","format-standard","hentry","category-antennas","category-mediumwave","category-news","category-radios","category-ultralight-dx","tag-dxing","tag-fsl-antenna","tag-fsl-phasing","tag-gary-debock","tag-gary-debock-ultralight-radio","tag-mediumwave-dxing","tag-ultralight-dx"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-bQD","jetpack-related-posts":[{"id":23072,"url":"https:\/\/swling.com\/blog\/2016\/12\/video-gary-debocks-baby-fsl-antenna\/","url_meta":{"origin":45547,"position":0},"title":"Video: Gary DeBock’s “Baby FSL” antenna","author":"Thomas","date":"December 30, 2016","format":false,"excerpt":"Many thanks to SWLing Post contributor,\u00a0Gary DeBock (N7EKX), who shares this video and notes the following on YouTube: This is the new 3.5 inch (89mm) \"Baby FSL\" antenna, designed to provide a powerful DXing gain boost for Ultralight radios (or any other portables) despite its very small size. It has\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/12\/BabyFSL.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/12\/BabyFSL.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/12\/BabyFSL.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":38261,"url":"https:\/\/swling.com\/blog\/2019\/06\/video-demonstration-of-gary-debocks-3-baby-fsl-antenna\/","url_meta":{"origin":45547,"position":1},"title":"Video Demonstration of Gary DeBock’s 3″ Baby FSL Antenna","author":"Thomas","date":"June 20, 2019","format":false,"excerpt":"Many thanks to SWLing Post contributor, Gary DeBock, who shares a video of his latest Ferrite Sleeve Loop (FSL) antenna: the 3\" Baby FSL. Gary Notes: The new design 3 Inch (76mm) Baby FSL antenna is the smallest, most compact and lightweight of the \"airport friendly\" FSL's developed here recently,\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/06\/Baby-FSL-Antenna-components-e1561029185374.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/06\/Baby-FSL-Antenna-components-e1561029185374.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/06\/Baby-FSL-Antenna-components-e1561029185374.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/06\/Baby-FSL-Antenna-components-e1561029185374.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":17892,"url":"https:\/\/swling.com\/blog\/2016\/03\/guest-post-jerrys-mediumwave-dxing-powerhouse-mini-fsl-antenna\/","url_meta":{"origin":45547,"position":2},"title":"Guest Post: Jerry’s Mediumwave DXing Powerhouse Mini FSL Antenna","author":"Thomas","date":"March 23, 2016","format":false,"excerpt":"Many thanks to SWLing Post contributor,\u00a0Jerry Popiel, for the following guest post: A MW DXing Powerhouse Mini FSL Antenna by\u00a0Jerry Popiel In late February 2016 I completed construction of a modified version of Gary DeBock's excellent 3 inch Mini FSL design (click here to view). This new antenna is nothing\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"PowerhouseFSLAntenna-1","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/PowerhouseFSLAntenna-1.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":24570,"url":"https:\/\/swling.com\/blog\/2017\/03\/daytime-dx-gary-compares-terk-advantage-with-homebrew-fsl-loop\/","url_meta":{"origin":45547,"position":3},"title":"Daytime DX: Gary compares Terk Advantage with homebrew FSL Loop","author":"Thomas","date":"March 9, 2017","format":false,"excerpt":"Many thanks to SWLing Post contributor, Gary DeBock, who shares the following: Daytime DX Shootout-- a new-design 4.7 inch FSL antenna ($62 construction cost) goes up against the Terk Advantage AM commercial loop ($58 on eBay) in the daytime DX reception of 650-CISL (10 kW at 160 miles, in Vancouver,\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/03\/Terk-FSL-Antenna-ShootOut-Gary-DeBock.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/03\/Terk-FSL-Antenna-ShootOut-Gary-DeBock.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/03\/Terk-FSL-Antenna-ShootOut-Gary-DeBock.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/03\/Terk-FSL-Antenna-ShootOut-Gary-DeBock.jpg?resize=700%2C400 2x"},"classes":[]},{"id":31799,"url":"https:\/\/swling.com\/blog\/2018\/04\/gary-debock-shares-most-distant-catch-from-cook-island-dxpedition\/","url_meta":{"origin":45547,"position":4},"title":"Gary DeBock shares most distant catch from Cook Island DXpedition","author":"Thomas","date":"April 28, 2018","format":false,"excerpt":"Many thanks to SWLing Post contributor, Gary DeBock, who shares the following note about his recent\u00a0Cook Island DXpedition: The farthest DX received during the Cook Island DXpedition (on Aitutaki island) was 657-All India Radio in Kolkata, India, at 8,072 miles (12,991 km). Recorded by accident during a sunrise check of\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/04\/Map-DX.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/04\/Map-DX.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/04\/Map-DX.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/04\/Map-DX.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":25235,"url":"https:\/\/swling.com\/blog\/2017\/04\/gary-debocks-ultralight-radio-dxpedition-in-hawaii\/","url_meta":{"origin":45547,"position":5},"title":"Gary DeBock’s Ultralight Radio DXpedition in Hawaii","author":"Thomas","date":"April 16, 2017","format":false,"excerpt":"Many thanks to SWLing Post contributor, Gary DeBock, who shares the following notes and recordings from an Ultralight DXpedition in Kona, Hawaii: The Kona, Hawaii Ultralight Radio DXpedition was conducted from a sixth floor oceanfront motel room in the Royal Kona Resort Motel from April 9-12 (during an anniversary trip\u2026","rel":"","context":"In "AM"","block_context":{"text":"AM","link":"https:\/\/swling.com\/blog\/category\/am\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/04\/Gary-DeBock-Kona-Hawaii-DXpedition-1024x523.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/04\/Gary-DeBock-Kona-Hawaii-DXpedition-1024x523.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/04\/Gary-DeBock-Kona-Hawaii-DXpedition-1024x523.jpg?resize=525%2C300 1.5x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/45547","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/comments?post=45547"}],"version-history":[{"count":0,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/45547\/revisions"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=45547"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=45547"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=45547"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}