On 10/29/2013 8:22 AM, MontyS wrote:
The rear mic jack is a mono, not stereo, jack. It will short the ring and sleeve together.
As Iain has noted, this is incorrect. It's a TRS jack that uses only the tip and sleeve contacts.
Audio is on the tip, as is the voltage.
Right.
The mic should have a blocking capacitor to isolate the audio from the voltage.
Nope. The mic includes a FET line drive that NEEDS the DC voltage to operate (the bias). In general, the value of voltage is non-critical, 5-8 VDC is in the range, and the voltage is applied through a series resistance in the range of 5-8 k Ohms. That's what's inside the K3, and you can use your PC mic with other rigs by making a suitable adapter for them wired in this manner.
Every ham rig I've seen manufactured in the past 30-40 years provides bias voltage in that range on one pin of the mic jack, and the input is DC blocked by a suitable capacitor.
73, Jim K9YC ______________________________________________________________ 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
