http://elecraft.85.s1.nabble.com/K2-connecting-a-condenser-mic-tp4480033p4480591.html
between pin 1 and pin 6 as is normally done. In the K3, you simply turn
> Thanks, Don.
>
> Not knowing any better, I simply shorted the AF and MICBIAS when I connected
> the mic to the K3. From what I can see in the K3 schematics, the only
> bypassing on the MICBIAS line is 1uF (rev B, sheet 5 of 7, "Front Panel -
> Miscellaneous"). Can I build the same resistor into the mic plug and use it
> that way for both the K2 and K3?
>
> Brian K1LI
>
> On Fri, Jan 29, 2010 at 9:34 AM, Don Wilhelm <
[hidden email]> wrote:
>
>
>> Brian,
>>
>> Is that a 3 terminal mic element? If so, then you can follow the
>> manufacturer's instructions and apply the 5 volts to the voltage terminal on
>> the element.
>> OTOH, most of these elements are 2 terminal, and the voltage should be
>> applied to the AF pin through a resistor - try 5.6k like the Elecraft MH2
>> uses as a first trial, it will likely work because the resistance is not
>> critical.
>> If you try to connect the 5 volts directly to the AF terminal, you will
>> effectively bypass all the audio to ground. For AC signals, a power rail is
>> jst the same as ground because there are large bypass capacitors on the
>> voltage rail.
>>
>> 73,
>> Don W3FPR
>>
>>
>> Brian Machesney wrote:
>>
>>
>>> I have a condenser mic that is not on the list of "known" mics in the docs
>>> or on the Elecraft web site. I'm trying to decide whether to simply short
>>> the +5V to the AF when connecting my condenser mic to the KSB2, or to
>>> place
>>> a resistor in between. I am more concerned about potential long-term
>>> adverse
>>> effects on the mic element by operating it out-of-spec than I am concerned
>>> with damaging the K2.
>>>
>>> A DMM shows the DC resistance of the element to be 400 Kohms! Not really
>>> surprising, I guess, since a condenser mic is electrically similar to a
>>> capacitor.
>>>
>>> The manufacturer specs the mic element at 4.5Kohms and 1.5V to 9.0V bias.
>>> Applying the KSB2's +5V directly to the mic element's 4.5K ohms should
>>> produce 1mA drain, no sweat for the KSB2, and right in the middle of the
>>> manufacturer's applied DC voltage spec.
>>>
>>> The manufacturer's tech sent me a wiring diagram that shows a +12V supply
>>> with a series resistor between 470 and 2.2K ohms to the mic. The 470 ohm
>>> resistor would apply nearly 11V to the mic, if the mic element and the
>>> series act as a pure voltage divider. The 2.2K ohm resistor would produce
>>> 8V
>>> at the mic.
>>>
>>> The KSB2 schematic shows a 2.2uF electrolytic cap between the MIC AF and
>>> the
>>> rest of the KSB2, so I wouldn't think there's any risk of a short.
>>>
>>> Help from those in the know, please?
>>>
>>>
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