[Elecraft] KX3: Cleaner audio with Yamaha CM500, also PTT

[Walter Underwood]

My blog post was mostly about providing clean mic bias with the KX3 for electrets that get bias from both tip and ring, like the Yamaha CM500.

Give it a quick read, it might answer some questions.

http://observer.wunderwood.org/2015/08/16/yamaha-cm500-headset-with-ptt-on-elecraft-kx3/

wunder
K6WRU
CM87wj
http://observer.wunderwood.org/ (my blog)

On Aug 16, 2015, at 9:20 PM, Jim Brown <jim at audiosystemsgroup.com> wrote:

> On Sun,8/16/2015 7:17 PM, Brian Denley wrote:
>> Don't electrets have to be powered (voltage applied) where dynamics do not?
> 
> Right.
> 
> On Sun,8/16/2015 8:00 PM, James Wilson wrote:
>> Yes, the electret mics do require a small amount of power - Elecraft
>> and others call it BIAS voltage.
> 
> It's called bias because it IS bias -- electret capsules have a very high output Z, so they use a FET follower as an output stage. The voltage provides bias for that output stage.
> 
>> Fortunately - with the K3 and K3S and very likely the KX3 also - that needed bias is available and can be turned on or off with a menu selection.
> 
> Virtually all modern rigs (within the last 30+ years) provide V+, usually about 8 V, on one pin of the mic connector. All it takes to use that for bias is a resistor in the range of 5K ohms from V+ to the mic input.
> 
> 73, Jim K9YC
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