{"id":16250,"date":"2015-12-19T09:33:15","date_gmt":"2015-12-19T13:33:15","guid":{"rendered":"http:\/\/swling.com\/blog\/?p=16250"},"modified":"2015-12-19T09:33:15","modified_gmt":"2015-12-19T13:33:15","slug":"icom-ic-r72-a-repair-story","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2015\/12\/icom-ic-r72-a-repair-story\/","title":{"rendered":"Icom IC-R72: a repair story"},"content":{"rendered":"

\"Icom-IC-R72-Front-Mehdi-Asgari\"In this post I’m going to tell you how I repaired my Icom IC-R72 receiver. Although it’s about a specific device, the logic\u00a0and methodology applies to all radios.<\/p>\n

I bought an Icom R72 from a friend for about $200. At first, I just checked 7.0MHZ (40 meter band) and 21.0MHZ (15 meter band) and it was OK. After some time, I tried to listen to some ham radio on 20 meters (14.0MHZ) and it was deaf! I checked everything: antenna connectors, balun…everything.<\/p>\n

With some trial and error, I found out that it was deaf from 11-15 MHz. With the help of the members of “Icom R72” Yahoo Group<\/a>, I found one of the usual suspects: bandpass filters’ switching diodes.<\/p>\n

I took a look at the service manual and apparently this radio uses multiple\u00a0bandpass filters \u00a0for different \u00a0frequency ranges.<\/p>\n

\"Schematic-Icom-R72-1\"<\/p>\n

As you see in the above\u00a0picture (grabbed from service manual), one of the bandpass filters is for 11-15 MHz range–that’s the range where my radio was deaf.<\/p>\n

Note that there are multiple ways to test that a radio is deaf at a frequency. One of the simplest ways: connect an antenna or even a long wire to the antenna socket of radio. The noise level should increase; if not, there’s a problem.<\/p>\n

\"Schematic-Icom-R72-2\"<\/p>\n

After testing diodes with a multimeter, I found out that D31 is faulty. Almost all multimeters have a diode-test functionality.<\/p>\n

I replaced it. The original diode was\u00a01SS53, but I used a 1N4148 which is very common and found everywhere. Now I have a working radio! \ud83d\ude42<\/p>\n

If you have a radio that’s deaf at a frequency range, there is probably a problem in bandpass filters.<\/p>\n

Here are some internal pictures of my Icom\u00a0IC-R72:<\/p>\n

\"IC-R72-Internal-IF-Stage-Mehdi\" \"IC-R72-Board-1\" \"IC-R72-Board-2\" \"Icom-IC-R72-Open\"<\/p>\n

I should thank my friend and electronics mentor, Saeed (EP2LSH)<\/strong> who always helps me in my electronics adventures.<\/p>\n

Mehdi Asgari, the author of this post, is a regular contributor to the SWLing Post. <\/em>Mehdi lives in Tehran and is an active member of the EP2C amateur radio club<\/a>.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

In this post I’m going to tell you how I repaired my Icom IC-R72 receiver. Although it’s about a specific device, the logic\u00a0and methodology applies to all radios. I bought an Icom R72 from a friend for about $200. At first, I just checked 7.0MHZ (40 meter band) and 21.0MHZ (15 meter band) and it […]<\/p>\n","protected":false},"author":56,"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":[3,139,26,43,1113],"tags":[4545,2884,4348,4546,4371,4537,4547],"class_list":["post-16250","post","type-post","status-publish","format-standard","hentry","category-news","category-radio-modifications","category-radios","category-shortwave-radio","category-tutorials","tag-bandpass-filters","tag-icom","tag-icom-ic-r72","tag-icom-ic-r72-repair","tag-mehdi","tag-mehdi-asgari","tag-radio-repair"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pn3uc-4e6","jetpack-related-posts":[{"id":16246,"url":"https:\/\/swling.com\/blog\/2015\/12\/how-to-use-the-sdrplay-rsp-as-a-panadapter\/","url_meta":{"origin":16250,"position":0},"title":"How to use the SDRPlay RSP as a panadapter","author":"Mehdi Asgari","date":"December 17, 2015","format":false,"excerpt":"In this post, I will show you how to use an SDR as a panadapter for a commercial communications receiver. I'm using an Icom R72 and a SDRPlay RSP, but you can do it with nearly all receivers and SDRs. The Icom R72 is a double conversion HF (0-30 MHz)\u2026","rel":"","context":"In "Ham Radio"","block_context":{"text":"Ham Radio","link":"https:\/\/swling.com\/blog\/category\/ham-radio\/"},"img":{"alt_text":"SDPlay-RSP","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/07\/SDPlay-RSP.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/07\/SDPlay-RSP.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2015\/07\/SDPlay-RSP.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":24362,"url":"https:\/\/swling.com\/blog\/2017\/02\/new-rx7300-adds-receive-only-antenna-port-to-icom-ic-7300\/","url_meta":{"origin":16250,"position":1},"title":"New RX7300 adds receive-only antenna port to Icom IC-7300","author":"Thomas","date":"February 23, 2017","format":false,"excerpt":"(Source: Southgate ARC) New receive antenna socket for IC 7300 IHSG and Vibroplex\/INRAD announce the release of a new accessory product for the Icom IC-7300 which provides a receive antenna socket on the rear of the radio. The INRAD model RX7300 allows the user to add a receive-only antenna jack\u2026","rel":"","context":"In "Accessories"","block_context":{"text":"Accessories","link":"https:\/\/swling.com\/blog\/category\/accessories\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/02\/RX7300-Receive-Antenna-Jack-Icom-IC-7300.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/02\/RX7300-Receive-Antenna-Jack-Icom-IC-7300.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/02\/RX7300-Receive-Antenna-Jack-Icom-IC-7300.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2017\/02\/RX7300-Receive-Antenna-Jack-Icom-IC-7300.jpg?resize=700%2C400 2x"},"classes":[]},{"id":45909,"url":"https:\/\/swling.com\/blog\/2020\/10\/icom-ic-705-blind-receiver-test-2\/","url_meta":{"origin":16250,"position":2},"title":"Icom IC-705 Blind Receiver Test #2","author":"Thomas","date":"October 10, 2020","format":false,"excerpt":"Test #2: 40 meters CW In this second test (click here for #1) we\u2019ll listen to the Icom IC-705, and one other comparable radio, tuned to a 40 meter CW station. Each recording is roughly the same length (2 minutes). I\u2019ve done my best to match these radios in terms\u2026","rel":"","context":"In "Ham Radio"","block_context":{"text":"Ham Radio","link":"https:\/\/swling.com\/blog\/category\/ham-radio\/"},"img":{"alt_text":"Icom IC-705","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/10\/IMG-2829-scaled-e1602354397783.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/10\/IMG-2829-scaled-e1602354397783.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/10\/IMG-2829-scaled-e1602354397783.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/10\/IMG-2829-scaled-e1602354397783.jpg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2020\/10\/IMG-2829-scaled-e1602354397783.jpg?resize=1050%2C600&ssl=1 3x"},"classes":[]},{"id":18326,"url":"https:\/\/swling.com\/blog\/2016\/04\/the-icom-ic-7300-vs-winradio-excalibur-which-do-you-prefer\/","url_meta":{"origin":16250,"position":3},"title":"The Icom IC-7300 vs. WinRadio Excalibur: Which do you prefer?","author":"Thomas","date":"April 18, 2016","format":false,"excerpt":"[UPDATE: Read the full IC-7300 review--along with listener survey results--by clicking here.] In the past, receiver shoot-outs\u00a0in which I've provided\u00a0sample audio for \"blind\" comparison\u2013\u2013meaning, the listener does not know which audio sample is associated with\u00a0which radio\u2013\u2013have\u00a0produced particularly positive feedback from Post readers. So I've decided to do this for the\u2026","rel":"","context":"In "Ham Radio"","block_context":{"text":"Ham Radio","link":"https:\/\/swling.com\/blog\/category\/ham-radio\/"},"img":{"alt_text":"Icom-IC-7300-Front","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/04\/Icom-IC-7300-Front-1.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/04\/Icom-IC-7300-Front-1.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/04\/Icom-IC-7300-Front-1.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/04\/Icom-IC-7300-Front-1.jpg?resize=700%2C400 2x"},"classes":[]},{"id":18642,"url":"https:\/\/swling.com\/blog\/2016\/05\/a-review-of-the-icom-ic-7300-direct-rf-sampling-transceiver\/","url_meta":{"origin":16250,"position":4},"title":"A review of the Icom IC-7300 direct RF sampling transceiver","author":"Thomas","date":"May 15, 2016","format":false,"excerpt":"In August 2015 at the Tokyo Hamfair, Icom debuted a new type of transceiver in their product line\u2013\u2013one featuring a direct RF sampling receiver. Essentially, it was an SDR tabletop transceiver. At about the same time that the IC-7300 started shipping around the world, Icom pulled their venerable IC-7200 off\u2026","rel":"","context":"In "New Products"","block_context":{"text":"New Products","link":"https:\/\/swling.com\/blog\/category\/new-products\/"},"img":{"alt_text":"Icom-IC-7300-Front","src":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/Icom-IC-7300-Front-1024x486.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/Icom-IC-7300-Front-1024x486.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2016\/03\/Icom-IC-7300-Front-1024x486.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":33395,"url":"https:\/\/swling.com\/blog\/2018\/08\/dave-reviews-the-icom-ic-r30-handheld-wide-band-receiver\/","url_meta":{"origin":16250,"position":5},"title":"Dave reviews the Icom IC-R30 Handheld Wide Band Receiver","author":"Thomas","date":"August 4, 2018","format":false,"excerpt":"Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who notes that he has published his comprehensive review of the Icom IC-R30 handheld wideband receiver. Click here to check out Dave's review. Based on Dave's evaluation, it sounds like this is one of the better wideband radios, although like similar\u2026","rel":"","context":"In "New Products"","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\/2018\/05\/2018-Hamvention-Photos-Sunday-6-of-11-768x1024.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/2018-Hamvention-Photos-Sunday-6-of-11-768x1024.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/swling.com\/blog\/wp-content\/uploads\/2018\/05\/2018-Hamvention-Photos-Sunday-6-of-11-768x1024.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/16250","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\/56"}],"replies":[{"embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/comments?post=16250"}],"version-history":[{"count":0,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/posts\/16250\/revisions"}],"wp:attachment":[{"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/media?parent=16250"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/categories?post=16250"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/swling.com\/blog\/wp-json\/wp\/v2\/tags?post=16250"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}