how much current can the 5V Mic bias handle?

[oe9fwv]

hi,

I would like to operate a cable GPS mouse the the K2 and it would be
convenient if I could steal the 5V from the Mic connector.
Will this be a problem - the current consumption is probably below 100mA.

73! de Werner
OE9FWV

--  
"I may be lost, but I know exactly where I am!" (GPS reading in Sibiria)



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[Stewart Baker]

Hi Werner,
I would not recommend this approach.

The +5v from the Mic connector is for delivering a low current.
It is susceptible to interference both in and out of the K2.

In addition any spiking on the +5V will effect the control board
MCU due to poor design of it's reset circuitry.

If you are happy making mods, then you can try this.

I put in a separate +5V supply to the Mic connector by using a 5V
regulator mounted on the front panel board and fed from the 8A
line on the RF board. There is a spare connector pin/socket (Pin 7
on J1) that is labeled AUXBUS(NC) which can be used to get the +8V
thru. Of course the existing feed must be disconnected.

73
Stewart G3RXQ

On Tue, 08 Jan 2008 09:53:15 +0100, Dr. Werner Furlan wrote:
> hi,
>
> I would like to operate a cable GPS mouse the the K2 and it
would be
> convenient if I could steal the 5V from the Mic connector.
> Will this be a problem - the current consumption is probably
below 100mA.
>
> 73! de Werner
> OE9FWV
>
> --
> "I may be lost, but I know exactly where I am!" (GPS reading in
Sibiria)

>
>
> PGP-Key: <http://www.qsl.net/oe9fwv/furlan.asc>
> Fone [phone]
> Fax [phone]
> Mobile      [phone]
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
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[oe9fwv]

hi Stewart,

On 8 Jan 2008 at 10:27, Stewart Baker wrote:

> Hi Werner,
> I would not recommend this approach.
>
> The +5v from the Mic connector is for delivering a low current.
> It is susceptible to interference both in and out of the K2.
>
> In addition any spiking on the +5V will effect the control board MCU
> due to poor design of it's reset circuitry.
>
> If you are happy making mods, then you can try this.
>
> I put in a separate +5V supply to the Mic connector by using a 5V
> regulator mounted on the front panel board and fed from the 8A line on
> the RF board. There is a spare connector pin/socket (Pin 7 on J1) that
> is labeled AUXBUS(NC) which can be used to get the +8V thru. Of course
> the existing feed must be disconnected.
>
> 73
> Stewart G3RXQ

thank you for your advice .
I'll make a separate power supply. There is enough room for an 7805
voltage regulator on the relais board I have added to switch the TrxPtc in my
K2. This way I avoid any problem you have mentioned.

73! de Werner
OE9FWV

--  
 Wenn du deine Frau so hasst, warum schenkst du ihr nicht einen PC mit
Windows95?



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