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K3s: microphone connector 8V current

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K3s: microphone connector 8V current

Hi all,
At the K3s microphone connector the 8V output (pin 6) is specified at 10 mA max.However a UA78M08CDC voltage regulator - which is directly connected to +12V - provides the voltage/current to this pin.The UA78M08CDC is specified at 500 mA max.
Is there any reason why a current of approx. 50 mA could not be drawn from pin 6?
73 HenkPA0C
Henk
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Nr4c

Re: K3s: microphone connector 8V current

What are you going to use this voltage for? I think it’s for a mic preamp. It is not the source of bias for an electret mic. That comes on the mic pin when turned On in the menu.

Sent from my iPhone
...nr4c. bill

> On Jul 26, 2020, at 2:57 PM, Henk de Vries <[hidden email]> wrote:
>
> Hi all,
> At the K3s microphone connector the 8V output (pin 6) is specified at 10 mA max.However a UA78M08CDC voltage regulator - which is directly connected to +12V - provides the voltage/current to this pin.The UA78M08CDC is specified at 500 mA max.
> Is there any reason why a current of approx. 50 mA could not be drawn from pin 6?
> 73 HenkPA0C
> Henk
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
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Don Wilhelm

Re: K3s: microphone connector 8V current

Henk,

If indeed it is for a mic preamp, then try it without the preamp. The
K3S has 2 stages of mic AF gain. Normal for the usual ham mics, and a
Hi level for low gain mic elements.

You must turn on bias to have the 8 volts appear at the mic jack. Do
not use with direct connection of a dynamic mic - it makes the mic
'sound funny'.

73,
Don W3FPR

On 7/26/2020 5:40 PM, Nr4c wrote:
> What are you going to use this voltage for? I think it’s for a mic preamp. It is not the source of bias for an electret mic. That comes on the mic pin when turned On in the menu.
>
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Grant Youngman-2

Re: K3s: microphone connector 8V current

I have the same question about the current available for the 8V at the mic connector. Is it limited to 10ma, or will it actually support a somewhat higher continuous current draw safely. Not just for the k3, but also the K4.

Grant NQ5T

> On Jul 26, 2020, at 7:46 PM, Don Wilhelm <[hidden email]> wrote:
>
> Henk,
>
> If indeed it is for a mic preamp, then try it without the preamp. The K3S has 2 stages of mic AF gain. Normal for the usual ham mics, and a Hi level for low gain mic elements.
>
> You must turn on bias to have the 8 volts appear at the mic jack. Do not use with direct connection of a dynamic mic - it makes the mic 'sound funny'.
>
> 73,
> Don W3FPR
>
> On 7/26/2020 5:40 PM, Nr4c wrote:
>> What are you going to use this voltage for? I think it’s for a mic preamp. It is not the source of bias for an electret mic. That comes on the mic pin when turned On in the menu.
> ______________________________________________________________

Don Wilhelm

Re: K3s: microphone connector 8V current

Grant,

The MH2/MH4 mic does not use the 8 volts directly - there is a resistor
between the 8 volt supply and the AF line,
and that is where the 10ma is used to power the electret elemant.
The 10 ma. used by the microphone has nothing to do with the total
current available from pin 6.

73,
Don W3FPR

On 7/26/2020 8:05 PM, Grant Youngman wrote:

> I have the same question about the current available for the 8V at the mic connector. Is it limited to 10ma, or will it actually support a somewhat higher continuous current draw safely. Not just for the k3, but also the K4.
>
> Grant NQ5T
>
>
>> On Jul 26, 2020, at 7:46 PM, Don Wilhelm <[hidden email]> wrote:
>>
>> Henk,
>>
>> If indeed it is for a mic preamp, then try it without the preamp. The K3S has 2 stages of mic AF gain. Normal for the usual ham mics, and a Hi level for low gain mic elements.
>>
>> You must turn on bias to have the 8 volts appear at the mic jack. Do not use with direct connection of a dynamic mic - it makes the mic 'sound funny'.
>>
>> 73,
>> Don W3FPR
>>
>> On 7/26/2020 5:40 PM, Nr4c wrote:
>>> What are you going to use this voltage for? I think it’s for a mic preamp. It is not the source of bias for an electret mic. That comes on the mic pin when turned On in the menu.
>> ______________________________________________________________

Grant Youngman-2

Re: K3s: microphone connector 8V current

i’m not interesting in using the 8V line for mic element bias. That was someone else. My application is to power an external device between a mic and a K3/K4 from that line.

I can, of course, use a battery. But it would be much simpler if the 8V line could supply at least 20ma without releasing smoke :-)

The individual that asked this question initially, was looking for the possibility of 50ma.

Grant NQ5T

> On Jul 26, 2020, at 8:21 PM, Don Wilhelm <[hidden email]> wrote:
>
> Grant,
>
> The MH2/MH4 mic does not use the 8 volts directly - there is a resistor between the 8 volt supply and the AF line,
> and that is where the 10ma is used to power the electret elemant.
> The 10 ma. used by the microphone has nothing to do with the total current available from pin 6.
>
> 73,
> Don W3FPR
>
> On 7/26/2020 8:05 PM, Grant Youngman wrote:
>> I have the same question about the current available for the 8V at the mic connector. Is it limited to 10ma, or will it actually support a somewhat higher continuous current draw safely. Not just for the k3, but also the K4.
>>
>> Grant NQ5T
>>
>>
>>> On Jul 26, 2020, at 7:46 PM, Don Wilhelm <[hidden email]> wrote:
>>>
>>> Henk,
>>>
>>> If indeed it is for a mic preamp, then try it without the preamp. The K3S has 2 stages of mic AF gain. Normal for the usual ham mics, and a Hi level for low gain mic elements.
>>>
>>> You must turn on bias to have the 8 volts appear at the mic jack. Do not use with direct connection of a dynamic mic - it makes the mic 'sound funny'.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 7/26/2020 5:40 PM, Nr4c wrote:
>>>> What are you going to use this voltage for? I think it’s for a mic preamp. It is not the source of bias for an electret mic. That comes on the mic pin when turned On in the menu.
>>> ______________________________________________________________
>