{"id":30743,"date":"2018-02-05T12:05:56","date_gmt":"2018-02-05T16:05:56","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=30743"},"modified":"2018-02-05T12:05:56","modified_gmt":"2018-02-05T16:05:56","slug":"the-airspy-hf-r3-bypass-modification","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2018\/02\/the-airspy-hf-r3-bypass-modification\/","title":{"rendered":"The AirSpy HF+ R3 bypass modification"},"content":{"rendered":"<p><a href=\"https:\/\/swling.com\/blog\/wp-content\/uploads\/2017\/12\/Airspy-HF-Plus-SDR.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-29444\" src=\"https:\/\/swling.com\/blog\/wp-content\/uploads\/2017\/12\/Airspy-HF-Plus-SDR.jpg\" alt=\"\" width=\"800\" height=\"520\" srcset=\"https:\/\/swling.com\/blog\/wp-content\/uploads\/2017\/12\/Airspy-HF-Plus-SDR.jpg 800w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2017\/12\/Airspy-HF-Plus-SDR-300x195.jpg 300w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2017\/12\/Airspy-HF-Plus-SDR-768x499.jpg 768w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2017\/12\/Airspy-HF-Plus-SDR-624x406.jpg 624w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/a>After <em>SWling Post<\/em> contributor, Guy Atkins, posted the survey results of his excellent <a href=\"https:\/\/swling.com\/blog\/2018\/02\/results-airspy-hf-vs-elad-fdm-s2-weak-signal-comparisions\/\">Elad FDM-S2\u00a0 vs AirSpy HF+ weak signal comparison<\/a>, I received a few questions about the AirSpy HF+\u00a0 &#8220;R3 Bypass&#8221; modification Guy mentioned in his post.<\/p>\n<p>Guy has not yet performed the modification on his HF+&#8211;neither have I&#8211;but he points out that others have noted it:<em> &#8220;significantly boosts sensitivity of the HF+ from longwave up to about 15 MHz, without any noted overload issues.&#8221;<\/em><\/p>\n<p>I reached out to AirSpy president, Youssef Touil, for a little more insight about this modification. Youssef replied:<\/p>\n<blockquote><p>During the early phases of the design R3 was a place holder for a 0 ohms resistor that allows experimenters to customize the input impedance. For example:<\/p>\n<ul>\n<li>A 300 pF capacitor will naturally filter the LW\/MW bands for better performance in the HAM bands<\/li>\n<li>A 10\u00b5H inductor would allow the use of electrically short antennas (E-Field probes) for MW and LW<\/li>\n<li>A short (or high value capacitor) would get you the nominal 50 ohms impedance over the entire band, but then it\u2019s the responsibility of the user to make sure his antenna has the right gain at the right band<\/li>\n<li>A custom filter can also be inserted between the SMA and the tuner block if so desired.<\/li>\n<\/ul>\n<div id=\"attachment_30745\" style=\"width: 635px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-30745\" class=\"size-large wp-image-30745\" src=\"https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo-1024x521.jpg\" alt=\"\" width=\"625\" height=\"318\" srcset=\"https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo-1024x521.jpg 1024w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo-300x153.jpg 300w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo-768x391.jpg 768w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo-624x318.jpg 624w, https:\/\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/airspy_hf_photo.jpg 1080w\" sizes=\"auto, (max-width: 625px) 100vw, 625px\" \/><\/a><p id=\"caption-attachment-30745\" class=\"wp-caption-text\">Click to enlarge. (Photo source: RTL-S1DR.com)<\/p><\/div>\n<p>R3 and the nearby resistors have been intentionally left outside of the RF shield, and their size was picked to be big enough to allow anyone to play with them. You will notice the size difference with the rest of the components.<\/p>\n<p>In general, unless one knows what he\u2019s doing, it\u2019s not recommended to alter a working system. \u201cIf it\u2019s working, don\u2019t fix it\u201d. But, we are hobbyists, and not doing so leaves an uncomfortable feeling of something unachieved. Most brands addressing the hobby market leave some tweaks and even label them in the PCB.<\/p>\n<p>The main purpose of the HF+ is the best possible performance on HF at an affordable price. This is to incite HAMs to get started with this wonderful technology while using an SDR that isn\u2019t worse than their existing analog rig.<\/p>\n<p>The MW\/LW\/VLF crowd may have slightly different requirements, but that can be addressed by shorting a resistor.<\/p>\n<p>Regards,<\/p>\n<p>Youssef Touil<\/p><\/blockquote>\n<p>Thank you, Youssef, for replying to my inquiry so quickly and thoroughly.<\/p>\n<p>No doubt, I too will eventually modify R3&#8211;it&#8217;s very difficult not to experiment, especially when a product was designed with the experimenter in mind.<\/p>\n<p>I really feel like AirSpy has knocked it out of the ballpark with the HF+. For those of us primarily concerned with HF performance, this SDR is <em>very<\/em> hard to beat&#8211;especially at its $199 price point!<\/p>\n","protected":false},"excerpt":{"rendered":"<p>After SWling Post contributor, Guy Atkins, posted the survey results of his excellent Elad FDM-S2\u00a0 vs AirSpy HF+ weak signal comparison, I received a few questions about the AirSpy HF+\u00a0 &#8220;R3 Bypass&#8221; modification Guy mentioned in his post. Guy has not yet performed the modification on his HF+&#8211;neither have I&#8211;but he points out that others [&hellip;]<\/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":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[836,3,139,26,43,158],"tags":[3724,6613,6819,4331,157,4087],"class_list":["post-30743","post","type-post","status-publish","format-standard","hentry","category-new-products","category-news","category-radio-modifications","category-radios","category-shortwave-radio","category-software-defined-radio","tag-airspy","tag-airspy-hf","tag-airspy-hf-r3-bypass-modification","tag-modifications","tag-sdr","tag-software-defined-radio"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-7ZR","jetpack-related-posts":[{"id":30705,"url":"https:\/\/swling.com\/blog\/2018\/02\/results-airspy-hf-vs-elad-fdm-s2-weak-signal-comparisions\/","url_meta":{"origin":30743,"position":0},"title":"Results: AirSpy HF+ vs Elad FDM-S2 Weak Signal Comparisions","author":"Guy Atkins","date":"February 3, 2018","format":false,"excerpt":"Looking north toward Cape Lookout, Oregon, near the site of my SDR receiver recordings. Photo courtesy of Wikimedia Commons. In my original article 10 days ago, I set up a SWLing Post reader poll to let you give your opinion on which shortwave recordings within four pairs of audio files\u2026","rel":"","context":"In &quot;DX&quot;","block_context":{"text":"DX","link":"https:\/\/swling.com\/blog\/category\/dx\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/12\/Camp_Meriwether_Cape_Lookout_State_Park.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/12\/Camp_Meriwether_Cape_Lookout_State_Park.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/12\/Camp_Meriwether_Cape_Lookout_State_Park.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/12\/Camp_Meriwether_Cape_Lookout_State_Park.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":31994,"url":"https:\/\/swling.com\/blog\/2018\/05\/ivan-performs-two-tests-with-the-airspy-hf\/","url_meta":{"origin":30743,"position":1},"title":"Ivan performs two tests with the AirSpy HF+","author":"Thomas","date":"May 11, 2018","format":false,"excerpt":"Many thanks to SWLing Post contributor,\u00a0Ivan Cholakov (NO2CW), who shares the following: Thomas, there has been a lot of discussions regarding Airspy HF+ ever since it came out - heated exchanges regarding comparisons with peers, modifications and firmware updates. I took my Airspy HF+ and conducted two tests with it:\u2026","rel":"","context":"In &quot;AM&quot;","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\/05\/Airspy-Ivan.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/Airspy-Ivan.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/Airspy-Ivan.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/Airspy-Ivan.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":42582,"url":"https:\/\/swling.com\/blog\/2020\/03\/the-airspy-youloop-is-a-freaking-brilliant-passive-loop-antenna\/","url_meta":{"origin":30743,"position":2},"title":"The Airspy Youloop is a freaking brilliant passive loop antenna","author":"Thomas","date":"March 30, 2020","format":false,"excerpt":"Before I start talking Youloop, I have a little confession to make up front: At the Winter SWL Fest when I gave a presentation about Portable SDR DXing, not only did I give attendees the wrong name of the Airspy Youloop antenna, but I also configured it incorrectly, hence the\u2026","rel":"","context":"In &quot;Antennas&quot;","block_context":{"text":"Antennas","link":"https:\/\/swling.com\/blog\/category\/antennas\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Red-Oxx-Lil-Roy.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Red-Oxx-Lil-Roy.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Red-Oxx-Lil-Roy.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/03\/Red-Oxx-Lil-Roy.jpeg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":30735,"url":"https:\/\/swling.com\/blog\/2018\/02\/video-comparing-the-sdrplay-rsp1a-and-airspy-hf-on-hf-mw\/","url_meta":{"origin":30743,"position":3},"title":"Video: Comparing the SDRplay RSP1A and Airspy HF+ on HF &#038; MW","author":"Thomas","date":"February 5, 2018","format":false,"excerpt":"Many thanks to SWLing Post contributor, Ivan Cholakov, who shares the following video where he compares the SDRplay RSP1A and the AirSpy HF+ software defined radios on shortwave and mediumwave: https:\/\/youtu.be\/Ff3SG_Mwt9Y Click here to watch on YouTube.","rel":"","context":"In &quot;AM&quot;","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\/02\/Ivan-RSP1a-screen-grab.jpeg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/Ivan-RSP1a-screen-grab.jpeg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/Ivan-RSP1a-screen-grab.jpeg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/02\/Ivan-RSP1a-screen-grab.jpeg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":37967,"url":"https:\/\/swling.com\/blog\/2019\/05\/the-airspy-hf-discovery-a-new-high-performance-sdr\/","url_meta":{"origin":30743,"position":4},"title":"The Airspy HF+ Discovery: A new high-performance SDR","author":"Thomas","date":"May 27, 2019","format":false,"excerpt":"At the 2019 Hamvention, I stopped by the Airspy.US booth and checked out the specifications of Airspy's latest SDR: the Airspy HF+ Discovery. At first glance, the Discovery looks a lot like the Airspy HF+ but even smaller and sporting performance upgrades. Keep in mind, I consider the Airspy HF+\u2026","rel":"","context":"In &quot;New Products&quot;","block_context":{"text":"New Products","link":"https:\/\/swling.com\/blog\/category\/new-products\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/05\/Airspy-HF-Plus-Discovery-PCB.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/05\/Airspy-HF-Plus-Discovery-PCB.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/05\/Airspy-HF-Plus-Discovery-PCB.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2019\/05\/Airspy-HF-Plus-Discovery-PCB.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":29087,"url":"https:\/\/swling.com\/blog\/2017\/11\/airspy-hf-sdr-now-available-to-order\/","url_meta":{"origin":30743,"position":5},"title":"Airspy HF+ SDR Now Available to Order","author":"Guy Atkins","date":"November 10, 2017","format":false,"excerpt":"As reported recently on the SWLing Post that the Airspy HF+\u00a0 would be available \"really, really, really soon\", the rumor has become reality--this new SDR receiver is for sale on Airspy's main sale site www.Itead.cc. The direct link for purchase is:\u00a0https:\/\/www.itead.cc\/airspy-hf-plus.html.\u00a0\u00a0The price in US dollars is a very reasonable $199.00,\u2026","rel":"","context":"In &quot;Manufacturers&quot;","block_context":{"text":"Manufacturers","link":"https:\/\/swling.com\/blog\/category\/manufacturers\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/11\/Airspy-HF-plus-293x300.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/30743","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=30743"}],"version-history":[{"count":0,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/30743\/revisions"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=30743"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=30743"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=30743"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}