{"id":15656,"date":"2022-01-18T00:37:32","date_gmt":"2022-01-18T08:37:32","guid":{"rendered":"https:\/\/mightyohm.com\/blog\/?page_id=15656"},"modified":"2022-01-18T00:43:50","modified_gmt":"2022-01-18T08:43:50","slug":"sbm-20-tube-specs","status":"publish","type":"page","link":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/sbm-20-tube-specs\/","title":{"rendered":"SBM-20 Tube Specs"},"content":{"rendered":"

The SBM-20 is one of the most popular GM tubes for hobby Geiger Counter and radiation monitoring projects. It is relatively sensitive and easy to use.<\/p>\n

There are many example circuits online that will help you build a Geiger Counter using this tube.<\/p>\n

One example is the MightyOhm Geiger Counter Kit: http:\/\/mightyohm.com\/geiger<\/em><\/a><\/p>\n

The SBM-20 is most sensitive to hard beta and gamma radiation. It is important to note that due to the thick walls of the tube, the SBM-20 is NOT sensitive to alpha radiation (the walls block the alpha particles), so it is not a good choice for samples that primarily emit alpha radiation, such as Americium. However, it will still detect some of the decay products (those that emit beta or gamma radiation).<\/p>\n

Please note that the thin walls are easily damaged. Handle the tube gently to avoid crushing it. Do not drop the tube.<\/p>\n

Please consider your safety and the safety of others when using this tube. The tube requires high voltages to operate (approx. 400V) which may pose a risk of electric shock. Also, exposure to radiation, even in small amounts, may be harmful to your health.<\/p>\n

For more information, please visit: http:\/\/www.cdc.gov\/nceh\/radiation\/safety.html<\/em><\/a><\/p>\n

General Specifications (see notes below)<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/strong><\/td>\nUnits<\/strong><\/td>\nSpecification<\/strong><\/td>\n<\/tr>\n
Overall Length<\/td>\nmm<\/td>\n108 \u00b1 3.5<\/td>\n<\/tr>\n
Overall Diameter<\/td>\nmm<\/td>\n10 \u00b1 1<\/td>\n<\/tr>\n
Weight<\/td>\ngrams<\/td>\n10 (nominal)<\/td>\n<\/tr>\n
Operating Temperature Range<\/td>\n\u00b0C<\/td>\n-50 to +70<\/td>\n<\/tr>\n
Lifetime<\/td>\npulses (min)<\/td>\n2e10<\/td>\n<\/tr>\n
–<\/td>\n–<\/td>\n–<\/td>\n<\/tr>\n
Nominal Working Voltage<\/td>\nvolts<\/td>\n400<\/td>\n<\/tr>\n
Operating Voltage Range<\/td>\nvolts<\/td>\n350 – 475<\/td>\n<\/tr>\n
Recommended Anode Resistor<\/td>\nohms<\/td>\n5.1M (5.1e6)<\/td>\n<\/tr>\n
Impulse Amplitude<\/td>\nvolts<\/td>\n50 (min)<\/td>\n<\/tr>\n
Maximum tube current<\/td>\namps<\/td>\n20u (20e-6)<\/td>\n<\/tr>\n
Tube Capacitance<\/td>\npF<\/td>\n4.2<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Keep in mind that these tubes are \u201cnew old stock\u201d and most have been in storage for some time. They may not meet all of the original manufacturer\u2019s specifications.<\/em><\/p>\n

In addition, the specifications above have been collected from several sources (there is no single definitive datasheet) and may be subject to change. There are more specs here:\u00a0http:\/\/www.gstube.com\/data\/2398\/<\/a><\/em><\/p>\n

If you have feedback or suggestions, please use the Contact Form<\/a> to submit them.<\/em><\/p>\n

\u00a0<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

The SBM-20 is one of the most popular GM tubes for hobby Geiger Counter and radiation monitoring projects. It is relatively sensitive and easy to use. There are many example circuits online that will help you build a Geiger Counter using this tube. One example is the MightyOhm Geiger Counter Kit: http:\/\/mightyohm.com\/geiger The SBM-20 is … Continue reading SBM-20 Tube Specs<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"parent":4074,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-15656","page","type-page","status-publish","hentry"],"jetpack_shortlink":"https:\/\/wp.me\/PioCd-44w","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":4074,"url":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/","url_meta":{"origin":15656,"position":0},"title":"Geiger Counter","author":"Jeff","date":"August 5, 2011","format":false,"excerpt":"Introducing the MightyOhm Geiger Counter kit! Geiger Kit Options Kit with Laser-Cut Case and SBM-20 Geiger Tube $114.90 USD Kit with SBM-20 Geiger Tube (no case) $99.95 USD Kit without Geiger Tube or Case $49.95 USD Laser-cut Case Only $14.95 USD Bare PCB Only $12.00 USD Assembly Instructions Case Assembly\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"OSHW logo","src":"https:\/\/i0.wp.com\/mightyohm.com\/files\/geiger\/images\/6275026497_3cf9f175b2_c.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":4091,"url":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/usage-instructions\/","url_meta":{"origin":15656,"position":1},"title":"Usage Instructions","author":"Jeff","date":"August 5, 2011","format":false,"excerpt":"How to use it! Easy, turn on the switch and listen for clicks! Watch the LED, it will flash every time a beta particle or gamma ray hits the tube! (Note: The tube that comes with the kit is not sensitive to alpha particles.) If you get tired of hearing\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4523,"url":"https:\/\/mightyohm.com\/blog\/shipping-status\/","url_meta":{"origin":15656,"position":2},"title":"Shipping Status","author":"Jeff","date":"December 25, 2011","format":false,"excerpt":"Last updated May 26th, 2026: All variants of Geiger Counter kits are currently in stock. Bundled kits that include a case and SBM-20 Geiger tube are also available from Amazon.com. For fastest shipping of Geiger Counter kits, please order a boxed kit from Amazon (link). I'm also happy to ship\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4288,"url":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/case-assembly-instructions\/","url_meta":{"origin":15656,"position":3},"title":"Case Assembly Instructions","author":"Jeff","date":"October 23, 2011","format":false,"excerpt":"Ready to assemble your case? \u00a0Ok, let's go! \u00a0These instructions will show you how. \u00a0Case assembly should take\u00a0about 5-10 minutes, more if you want to swap out the existing mute button on your geiger counter for the new microswitch included with the case. There is also a printed version of\u2026","rel":"","context":"With 1 comment","block_context":{"text":"With 1 comment","link":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/case-assembly-instructions\/#comments"},"img":{"alt_text":"Geiger Counter Case","src":"https:\/\/i0.wp.com\/mightyohm.com\/files\/geiger\/images\/6273801959_ef0d6f7218.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":4086,"url":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/support\/","url_meta":{"origin":15656,"position":4},"title":"Support","author":"Jeff","date":"August 5, 2011","format":false,"excerpt":"For support, please go to the Geiger Counter Kit\u00a0support forum. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":4089,"url":"https:\/\/mightyohm.com\/blog\/products\/geiger-counter\/assembly-instructions\/","url_meta":{"origin":15656,"position":5},"title":"Assembly Instructions","author":"Jeff","date":"August 5, 2011","format":false,"excerpt":"Download the assembly instructions here. (Last updated 3\/15\/2022.)","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"_links":{"self":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/pages\/15656","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/comments?post=15656"}],"version-history":[{"count":4,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/pages\/15656\/revisions"}],"predecessor-version":[{"id":15660,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/pages\/15656\/revisions\/15660"}],"up":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/pages\/4074"}],"wp:attachment":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/media?parent=15656"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}