[Elecraft] K3 Rear Panel Microphone Jack Bias Voltage

[paul alexander]

Steve--

I tried just inserting a bare plug into the jack, with no microphone
wires attached and measured no bias voltage on the rear jack.  One of
my first thoughts was that the microphone had a short in it, but, that
was not the case.

Thanks for the suggestion.

Paul Alexander
wb9ipa

On Sun, Apr 26, 2009 at 9:11 PM, Steve Ellington <n4lq at carolina.rr.com> wrote:
> Paul
> If you unplug that mic from the rear panel jack, can you measure any bias
> v.? I use a computer mic on the RP with bias set for rP.H BIAS.
> Steve Ellington
> N4LQ at carolina.rr.com
> ----- Original Message ----- From: "paul alexander" <wb9ipa at gmail.com>
> To: <elecraft at mailman.qth.net>
> Sent: Sunday, April 26, 2009 8:54 PM
> Subject: [Elecraft] K3 Rear Panel Microphone Jack Bias Voltage
>
>
>> I recently assembled my K3 and am having some trouble getting a
>> microphone to operate.  All of my station microphones are  Motorola
>> handheld microphones.  These are dynamic microphones which have a
>> built-in amplifier, to make them appear as carbon microphones.  As
>> such, they require bias voltage.
>>
>> My first attempt was to connect the microphone via the rear panel
>> jack, using the following menu settings:
>>   Mic SEL
>>        rPL.bIAS
>> and
>>   MIc + LIn
>>        On
>>
>> Under these settings, I get no bias voltage on the rear panel microphone
>> jack.
>>
>> When I set Mic SEL for FPL.bIAS, I get bias voltage on the front
>> panel, and a microphone connected to the front panel connection works
>> as expected.
>>
>> FYI, the radio Serial Number is 2925 and the firmware is version 1.98,
>> MAR 31, 2009.
>>
>> Is it not possible to get microphone bias voltage on the rear panel
>> connector?  Do I have something set up incorrectly?
>>
>> Any suggestions would be appreciated.
>>
>> Thank-you
>>
>> Paul Alexander
>> wb9ipa
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>