{"id":3342,"date":"2018-05-29T08:43:37","date_gmt":"2018-05-29T15:43:37","guid":{"rendered":"http:\/\/blackcap.name\/blog\/new\/?p=3342"},"modified":"2018-05-29T09:28:20","modified_gmt":"2018-05-29T16:28:20","slug":"warning-bad-instructions-for-ubitx","status":"publish","type":"post","link":"https:\/\/blackcap.name\/blog\/new\/?p=3342","title":{"rendered":"Warning: Bad Instructions for uBITX"},"content":{"rendered":"

The official instructions for the uBITX transceiver kit recommend wiring the hot side of the audio out to both the tip and ring connectors. I consider this to be a faulty design and thus an error.<\/p>\n

If you plug a stereo device into the jack wired per those instructions, it will work. If you plug a monaural device into the jack, it will cause a short circuit between ring and sleeve, because the sleeve on a mono plug is longer than the sleeve on a stereo one (the tips being the same size, and there being no ring). This short circuit can cause the receiver’s audio section<\/em> (specifically its output transistor) to self-destruct!<\/em><\/p>\n

Contrast that with wiring it with the hot side of the audio to tip only, as I recommend.<\/em> That way you have something that works completely with a monaural device and works somewhat (left channel only) on a stereo device. Works (to at least some degree) with both versus works on one and self-destructs on another. It’s pretty darn obvious which is the better engineering choice.<\/p>\n

This is mentioned on uBITX.net<\/a>, but it isn’t mentioned as prominently as some other errata are (or even labeled as an error), so I figured I’d mention it here. In my opinion, it definitely is<\/em> incorrect, because it qualifies as faulty design.<\/p>\n

It’s particularly nasty because the uBITX receiver is of course a monaural device, making it only logical to assume it has a standard monaural output. Murphy’s Law means that uBITX wired per the standard instructions will<\/em> sooner or later have an unwitting user (a guest, someone at Field Day, etc.) fall into this pitfall that was laid for them.<\/p>\n

What they were trying to do is use a stereo jack in a manner that causes both stereo and monaural devices to fully and properly work. There is<\/em> a way to do that: use a stereo jack whose sleeve is isolated from ground, and wire ground to ring and hot to tip. This will cause a mono plug to get signal presented at tip and sleeve, and a stereo one to get signal presented at tip and ring. The latter will result in both speakers being connected in series, if the sleeve is isolated from ground.<\/em><\/p>\n

If the latter is not the case (and it cannot be with a metal case and the stock jacks furnished with the uBITX), ring and sleeve will end up being shorted and you’re back to seeing a signal in the left channel only. Not drastic, but not the full universal performance desired, either.<\/p>\n

Instead of using a nonstandard technique that paves the path to a future mishap, it’s far better to just wire it as a mono device and use an easily-obtainable external mono-to-stereo adaptor if you want to feed audio to a stereo device.<\/p>\n","protected":false},"excerpt":{"rendered":"

The official instructions for the uBITX transceiver kit recommend wiring the hot side of the audio out to both the tip and ring connectors. I consider this to be a faulty design and thus an error. If you plug a stereo device into the jack wired per those instructions, it will work. If you plug […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-3342","post","type-post","status-publish","format-standard","hentry","category-radio"],"_links":{"self":[{"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=\/wp\/v2\/posts\/3342","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3342"}],"version-history":[{"count":0,"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=\/wp\/v2\/posts\/3342\/revisions"}],"wp:attachment":[{"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3342"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3342"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blackcap.name\/blog\/new\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3342"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}