[Today’s run: 1.x mile with wife and dog]<\/p>\n
I was reading an old article on varactor diodes in the QRP Classics book, written by Doug DeMaw of course.<\/p>\n
I have a nice QRP rig, the Willamette by NT7S, I use it all the time.\u00a0 It has varactor\u00a0 diode tuning.\u00a0 It works great but\u00a0 the diodes change capacitance in a non-linear fashion.\u00a0 So my frequency dial starts out at 14.000,\u00a0 and the intervals between tick marks becomes smaller and smaller, all the way up to 14.090.\u00a0 I make the dial nicer looking by changing the way I mark it up.\u00a0 At the low end I mark every kHz and put a bigger mark on the 5’s.\u00a0 When that starts to scrunch I\u00a0 skip to putting in marks for every even kHz and the 5.\u00a0 At the highest end I just have 10’s and 5’s marked\u00a0 (between .060 and .090).<\/p>\n
In the old days they used air-variable capacitors for tuning (a “bread slicer”), and they managed the tuning rate by making the fins of the capacitor a strange ‘D’ shape.\u00a0 The right shape would provide linear capacitance change over the range of motion of the capacitor elements.<\/p>\n
So, I’ve been pondering how to linearize the varactor capacitance curve.\u00a0 Really haven’t found a solution yet.\u00a0 (I probably never will, seeing as how there have been a lot of people smarter than me cover this ground multiple times… as part of their jobs… over the years.)<\/p>\n
But I thought it was a interesting problem.\u00a0 I’ll let you know if I think of anything.<\/p>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
[Today’s run: 1.x mile with wife and dog] I was reading an old article on varactor diodes in the QRP Classics book, written by Doug DeMaw of course. I have a nice QRP rig, the Willamette by NT7S, I use it all the time.\u00a0 It has varactor\u00a0 diode tuning.\u00a0 It works great but\u00a0 the diodes […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-1479","post","type-post","status-publish","format-standard","hentry","category-ham-radio"],"_links":{"self":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/1479","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1479"}],"version-history":[{"count":1,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/1479\/revisions"}],"predecessor-version":[{"id":1480,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/1479\/revisions\/1480"}],"wp:attachment":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1479"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1479"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1479"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}