{"id":88,"date":"2017-06-25T10:58:00","date_gmt":"2017-06-25T00:58:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2017\/06\/25\/mod-to-correct-design-error-in-heath-hw-8\/"},"modified":"2025-07-20T12:36:04","modified_gmt":"2025-07-20T02:36:04","slug":"mod-to-correct-design-error-in-heath-hw-8","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2017\/06\/25\/mod-to-correct-design-error-in-heath-hw-8\/","title":{"rendered":"Mod to Correct DESIGN ERROR in Heath HW-8"},"content":{"rendered":"\n\n\n\n
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130k resistor inside heat shrink, across R-24<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
SPRAT 161 (Winter 2014\/15) had a very intriguing article about the Heath HW-8 by Dave M0CEM. Dave wrote about a possible design error in the active filter of the receiver. The center frequency and gain shift significantly when you switch from “Wide” to “Narrow.” I was very interested because for many years I have noticed this problem in my own HW-8. I just left it in “Wide” and never used the more narrow filter. <\/b>
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Dave did some excellent circuit detective work and determined that the problem was R24. He prescribed a change: instead of 82k it should be 49.8k. The placement of a 130k resistor across the 81k R24 would have the same effect. <\/b><\/div>\n
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Yesterday morning I installed Dave’s mod. I did as he suggested and put a 130k resistor across R24. Brilliant! What a difference! In the past, I noticed a significant degradation in signal strength when I put the filter in the “Narrow” position. This doesn’t happen now — the response obviously does narrow, but the center freq stays the same.<\/b><\/div>\n
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It is really amazing to me that the Heath engineers made this error, and that it went uncorrected for so many years. There have been many, many modification articles for the HW-8 over the years, but I haven’t seen any that really address this problem. <\/b>

<\/b> If anyone has more info on how this design error happened and why it went uncorrected for so long, please let me know. <\/b><\/p>\n

Thanks to Dave and SPRAT for getting us back on the straight and narrow. <\/b>

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130k resistor inside heat shrink, across R-24 SPRAT 161 (Winter 2014\/15) had a very intriguing article about the Heath HW-8 by Dave M0CEM. Dave wrote about a possible design error in the active filter of the receiver. The center frequency and gain shift significantly when you switch from “Wide” to “Narrow.” I was very interested … Continue reading “Mod to Correct DESIGN ERROR in Heath HW-8”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":89,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16,15,17],"tags":[],"class_list":["post-88","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-filters","category-hw-8","category-sprat"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/88","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=88"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/88\/revisions"}],"predecessor-version":[{"id":90,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/88\/revisions\/90"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media\/89"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=88"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=88"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=88"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}