{"id":203,"date":"2024-02-13T17:07:25","date_gmt":"2024-02-13T17:07:25","guid":{"rendered":"https:\/\/www.bob-easton.com\/n4ree\/?p=203"},"modified":"2024-02-15T15:53:38","modified_gmt":"2024-02-15T15:53:38","slug":"yet-another-efhw-experiment","status":"publish","type":"post","link":"https:\/\/www.bob-easton.com\/n4ree\/2024\/02\/13\/yet-another-efhw-experiment\/","title":{"rendered":"Yet Another EFHW Experiment"},"content":{"rendered":"\n

Bottom line: It is a reasonable 3.5 band antenna. It resonates OK on 40M, very well on 20M, OK on 15M, and can be coerced for 18M, and NO-GO on all other bands.<\/p>\n\n\n\n

\"\"<\/a><\/figure>
\n

The design is found in an article that I have since lost (nobody specific to blame) and is based on making an End Fed Half Wave that is like many of the 40\/20\/15\/10 designs but is made shorter by using an R\/C network part way along the length. I don’t know the precise length and am too lazy to unwind and measure it. I’ll do that someday when I want to recycle the wire. \ud83d\ude42 My adjustment to the design was in winding the 36:1 transformer on a core different from the usual larger core. Colin, MM0OPX purports this core <\/a>to work better for frequencies above 20 Mhz. In reality, it didn’t work out that way for me. I also put some effort into packaging the transformer and BNC connector into a small streamlined form. <\/p>\n<\/div><\/div>\n\n\n\n

I launched it in the backyard in the usual inverted vee fashion of some of my other wires. Measurements with a NanoVNA produced these SWR values:<\/p>\n\n\n\n

\n
\n

Band<\/p>\n\n\n\n

40M<\/p>\n\n\n\n

20M<\/p>\n\n\n\n

15M<\/p>\n\n\n\n

10M<\/p>\n<\/div><\/div>\n\n\n\n

\n

Best Freq<\/p>\n\n\n\n

7.26<\/p>\n\n\n\n

13.9<\/p>\n\n\n\n

21.13<\/p>\n\n\n\n

28.45<\/p>\n<\/div><\/div>\n\n\n\n

\n

Best SWR<\/p>\n\n\n\n

1.35<\/p>\n\n\n\n

1.05<\/p>\n\n\n\n

1.57<\/p>\n\n\n\n

2.65<\/mark><\/p>\n<\/div><\/div>\n\n\n\n

\n

QRP Freq<\/p>\n\n\n\n

7.06<\/p>\n\n\n\n

14.06<\/p>\n\n\n\n

21.06<\/p>\n\n\n\n

28.06<\/p>\n<\/div><\/div>\n\n\n\n

\n

SWR<\/p>\n\n\n\n

1.69<\/p>\n\n\n\n

1.35<\/p>\n\n\n\n

1.62<\/p>\n\n\n\n

3.3<\/mark><\/p>\n<\/div><\/div>\n<\/div><\/div>\n\n\n\n

It becomes yet another addition to my antenna graveyard \/ spare parts bin.<\/p>\n","protected":false},"excerpt":{"rendered":"

Bottom line: It is a reasonable 3.5 band antenna. It resonates OK on 40M, very well on 20M, OK on 15M, and can be coerced for 18M, and NO-GO on all other bands. The design is found in an article that I have since lost (nobody specific to blame) and is based on making an […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[3],"tags":[],"class_list":{"0":"post-203","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-antennas","7":"entry"},"featured_image_src":null,"featured_image_src_square":null,"author_info":{"display_name":"Bob Easton","author_link":"https:\/\/www.bob-easton.com\/n4ree\/author\/n4ree\/"},"_links":{"self":[{"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/posts\/203","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/comments?post=203"}],"version-history":[{"count":3,"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/posts\/203\/revisions"}],"predecessor-version":[{"id":208,"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/posts\/203\/revisions\/208"}],"wp:attachment":[{"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/media?parent=203"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/categories?post=203"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bob-easton.com\/n4ree\/wp-json\/wp\/v2\/tags?post=203"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}