{"id":21188,"date":"2024-06-10T12:29:54","date_gmt":"2024-06-10T19:29:54","guid":{"rendered":"https:\/\/www.vernier.com\/til\/?p=21188"},"modified":"2025-04-02T08:54:56","modified_gmt":"2025-04-02T15:54:56","slug":"lower-than-expected-counts-with-go-direct-radiation-monitor-gdx-rad","status":"publish","type":"post","link":"https:\/\/www.vernier.com\/til\/21188","title":{"rendered":"Why do I get lower than expected counts with Go Direct Radiation Monitor (GDX-RAD)?"},"content":{"rendered":"<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<p class=\"wp-block-paragraph\">Some <a href=\"\/product\/go-direct-radiation-monitor\/\">Go Direct<sup>&reg;<\/sup> Radiation Monitor<\/a> (<nobr>GDX-RAD<\/nobr>) units (shipped in 2022 and 2023) contain a manufacturing error that limits the maximum count rate when monitoring active (&gt;500 counts per minute) radiation sources. Lower count rates do not appear to be affected.<\/p>\n<p class=\"wp-block-paragraph\">This flaw also makes the activity LED (labeled <strong>\u03b1 \u03b2 \u03b3<\/strong>) flash dimmer than normal, and the beep function, when enabled, is faint.<\/p>\n<\/div>\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"289\" height=\"171\" src=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-1-e1718111654700.jpeg\" alt=\"\" class=\"wp-image-21206\"\/><\/figure>\n<\/div>\n<\/div>\n<h2 class=\"wp-block-heading\">What units are affected?<\/h2>\n<p class=\"wp-block-paragraph\">You can identify affected units using the serial number and FCC ID number shown on the sensor labels as noted below.<\/p>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h3 class=\"wp-block-heading\">Affected Units<\/h3>\n<ul class=\"wp-block-list\">\n<li>Serial number starting with &#8220;<strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-kb-palette-17-color\">0C1<\/mark><\/strong>xxxxx&#8221; ALSO HAVING <br \/>FCC ID <strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-kb-palette-17-color\">QOQBGM12LMA<\/mark><\/strong> (shipped mostly in 2022)&nbsp;<\/li>\n<li>Serial number starting with &#8220;<strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-kb-palette-17-color\">0C3<\/mark><\/strong>xxxxx&#8221; WITH ID NUMBERS<br \/>0C300001 through 0C3002Y1<strong>*<\/strong> (shipped in 2023)&nbsp;<\/li>\n<\/ul>\n<div class=\"wp-block-group\">\n<div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<h3 class=\"wp-block-heading\">Unaffected Units<\/h3>\n<ul class=\"wp-block-list\">\n<li>Units shipped prior to 2022 (Serial number starting with 0C1xxxxx having FCC ID other than QOQBGM12LMA)&nbsp;<\/li>\n<li>Units shipped starting January 2024* (Serial number starting with 0C3xxxxx having ID numbers higher than 0C3002Y1)<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<p class=\"has-very-light-gray-background-color has-background has-small-font-size wp-block-paragraph\"><strong>*<\/strong> Serial number ranges and shipping dates are approximate. Other units may be affected. <\/p>\n<\/div>\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"507\" src=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD_ID-1024x507.png\" alt=\"\" class=\"wp-image-21210\" srcset=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD_ID-1024x507.png 1024w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD_ID-600x297.png 600w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD_ID-768x380.png 768w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD_ID-1536x761.png 1536w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD_ID-2048x1015.png 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"503\" height=\"1024\" src=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC-503x1024.png\" alt=\"\" class=\"wp-image-21211\" style=\"width:138px;height:auto\" srcset=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC-503x1024.png 503w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC-295x600.png 295w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC-768x1563.png 768w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC-755x1536.png 755w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC-1007x2048.png 1007w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/GDX-RAD-FCC.png 1525w\" sizes=\"auto, (max-width: 503px) 100vw, 503px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<div style=\"height:25px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<div class=\"wp-block-group\">\n<div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading\">Testing for the Defect<\/h2>\n<p class=\"wp-block-paragraph\">If you are uncertain if your device has been affected (or whether or not it has already been repaired), you can perform the following test to find out for sure. Since this defect creates lost counts only at higher count rates, a sufficiently active source is required to perform a definitive test. We used a Sr\u201390 (0.1 \u00b5Ci) exempt source from <a href=\"https:\/\/www.spectrumtechniques.com\/product\/rss3\/\">Spectrum Techniques<\/a>. (<em><strong>Note: <\/strong>we have not developed a definitive test that uses other sources.<\/em>)<\/p>\n<h3 class=\"wp-block-heading\">Testing Steps<\/h3>\n<ol class=\"wp-block-list\">\n<li>Fully charge the Go Direct Radiation sensor to be tested.&nbsp;<\/li>\n<li>Disconnect the sensor from the power source.<\/li>\n<li>Turn on the Go Direct Radiation Monitor. Do not connect it to Graphical Analysis or LabQuest App.&nbsp;<\/li>\n<li>Enable the audio beeps using the slide switch.<\/li>\n<li>Locate the flashing red Bluetooth LED. The Bluetooth LED will flash red about once a second.<\/li>\n<li>Locate the activity LED (labeled <strong>\u03b1 \u03b2 \u03b3<\/strong>).&nbsp;The activity LED will flash red when an alpha, beta, or gamma particle is detected.<\/li>\n<li>Place the Sr\u201390 source, label side out, centered over, and directly against, the screen of the detector.<\/li>\n<li>Notice the brightness of the Bluetooth and activity LEDs. Are they equally bright when lit? <br \/>(<em><strong>Note:<\/strong> if the activity LED stops flashing, remove the Sr\u201390 source then replace it to get the flashing to resume. Properly operating units will not stop flashing.<\/em>)&nbsp;<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h3 class=\"wp-block-heading\">Passes Test\u2015Unit is good<\/h3>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"726\" height=\"433\" src=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-2.jpeg\" alt=\"\" class=\"wp-image-21208\" srcset=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-2.jpeg 726w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-2-600x358.jpeg 600w\" sizes=\"auto, (max-width: 726px) 100vw, 726px\" \/><\/figure>\n<\/div>\n<ul class=\"wp-block-list\">\n<li>Bluetooth LED and activity LED are the same brightness when lit.<\/li>\n<li>The activity LED continues to flash without pause.<\/li>\n<li>Audio beeps are clear.<\/li>\n<\/ul>\n<\/div>\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h3 class=\"wp-block-heading\">Fails Test\u2015Unit needs repair<\/h3>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"728\" height=\"433\" src=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-3.jpeg\" alt=\"\" class=\"wp-image-21209\" srcset=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-3.jpeg 728w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-3-600x357.jpeg 600w\" sizes=\"auto, (max-width: 728px) 100vw, 728px\" \/><\/figure>\n<\/div>\n<ul class=\"wp-block-list\">\n<li>Bluetooth LED is significantly brighter than the activity LED when lit.<\/li>\n<li>The activity LED may pause for part of a second, or completely stop for several seconds.<\/li>\n<li>Audio beeps are faint.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div style=\"height:25px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<div class=\"wp-block-group\">\n<div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<h3 class=\"wp-block-heading\">Does your unit need repair?<\/h3>\n<p class=\"wp-block-paragraph\">If your Go Direct Radiation Monitor fails the test described above, Vernier will repair the device under our five year warranty. Contact our Tech Support team to set up a Return Merchandise Authorization (RMA) for this repair. <\/p>\n<p class=\"has-text-align-center has-very-light-gray-background-color has-background wp-block-paragraph\"><strong>To set up a repair, call us at 888-837-6437 or email <a href=\"mailto:support@vernier.com\">support@vernier.com<\/a>.<\/strong><br \/>Customers outside the US and Canada, please work through your local dealer.&nbsp;&nbsp;<\/p>\n<\/div>\n<\/div>\n<div style=\"height:25px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h2 class=\"wp-block-heading\">Additional Information<\/h2>\n<h3 class=\"wp-block-heading\">Count rate effects<\/h3>\n<p class=\"wp-block-paragraph\">The graph below show a comparison of a good unit (<mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">\u2b24<\/mark> A3) and a bad unit (<mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-kb-palette-17-color\">\u2b24<\/mark> A5). Notice that count rates below about 500 counts per minute are approximately the same for both units. Count rates above 500 counts per minute are very different. <\/p>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-1024x576.png\" alt=\"\" class=\"wp-image-21207\" srcset=\"https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-1024x576.png 1024w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-600x338.png 600w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-768x432.png 768w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image-1536x864.png 1536w, https:\/\/www.vernier.com\/til\/wp-content\/uploads\/sites\/2\/2024\/06\/image.png 1600w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Graph of counts per minute vs distance to a Sr\u201390 source.<\/figcaption><\/figure>\n<\/div>\n<h3 class=\"wp-block-heading\">What is causing the issue?<\/h3>\n<p class=\"wp-block-paragraph\">An incorrect part used in the unit prevents the high voltage power supply from adequately powering the Geiger tube\u00a0during high count rates. This cause counts to be missed. To fix the unit, the incorrect component must be replaced. The repair is not feasible for a customer to perform.\u00a0<\/p>\n<div style=\"height:25px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<h3 class=\"wp-block-heading\">Related Links<\/h3>\n<ul class=\"wp-block-list\">\n<li><a href=\"\/til\/3901\/\">Go Direct Radiation Monitor Troubleshooting and FAQs<\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>Some units (shipped in 2022 and 2023) contain a manufacturing error that limits the maximum count rate when monitoring active (&gt;500 counts per minute) radiation&#8230;<\/p>\n","protected":false},"author":8976,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[],"tags":[],"class_list":["post-21188","post","type-post","status-publish","format-standard","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/posts\/21188","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/users\/8976"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/comments?post=21188"}],"version-history":[{"count":0,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/posts\/21188\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/media?parent=21188"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/categories?post=21188"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vernier.com\/til\/wp-json\/wp\/v2\/tags?post=21188"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}