I own a MacBook Pro laptop -- current vintage, which means it has only one audio port. It's a 3.5mm jack that is designed to interface with the headset plug on Apple's "earbuds plus throat mike" headset. The plug on the Apple headset has a tip plus THREE rings, rather than the usual two for a 3.5mm stereo headset jack. The 3.5mm jack on the Mac (the "Audio Port") is supported by firmware/software that seems to detect when a plug is inserted that has less than a tip plus three rings. If I insert a standard 3.5mm stereo headset plug into the Audio Port and select "Use Audio Port for Sound Output" in Sound Preference, sound indeed flows to the headset. If I connect the K3 Line Out jack to the Audio Port on the Mac and select "Use Audio Port for Sound Input" in Sound Preferences, I get good quality sound input (verified by recording a QSO overheard on 40 meters) with sound recording software on the Mac). If I insert the Apple headset into the headset jack, Sound Preferences re cognizes that it has both an "external microphone" and "Headphones" connected to the "Built in Input" and "Built in Output" (respectively), which is of course the single Audio Port jack on the MacBook Pro.
I've been working to set up my Mac for digital work with my K3 using an iMic USB interface. Now, however, it has occurred to me that, since the Line In and Line Out jacks on the K3 are equipped with isolation transformers, I ought be able to modify an Apple headset to interface between the K3 and Mac. To do this, I think that all I would have to do is cut the Apple headset apart. I'd connect a 3.5mm mono plug to the wires that goes to the throat mike, and a 3.5mm stereo plug to the wires that go to the left and right earbuds. I'd insert the mono plug into the K3 Line In jack, and the stereo plug into the Line Out jack. The other end of the cable (with the Apple four-conductor configuration) would go into the Mac Audio Port. If I have it right, the Mac would think it was hooked up to a standard Apple headset, and the K3 would think it was hooked up with separate audio lines to Line IN and Line OUT> Is there any reason that this wouldn't work? Even more importantly, is there any reason that I shouldn't even TRY to make it work? (That is, would I be running the risk of damaging either the K3 or the Mac by putting voltage where it ought not to be). I have confirmed that I can input sound from the K3 to the Mac with a stereo cable connecting the K3 Line Out jack to the Mac headphone jack. I can't think of a way to verify that the sound output, which is at an appropriate level to drive headphones, would properly drive Line IN on the K3. But it seems to me that, worst case, the signal just isn't strong enough. Thanks in advance for any thoughts on this slightly whacko idea. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
