Anthony Bowyer wrote:
> I know I must be overlooking it, but I can't seem to
> find out what the max current is at the +4 volt Mic
> connector on the Omni V. Anyone have any idea?
>
> Thank you,
> Anthony
>
> =====
> NT4X
>
Hi Anthony.
No one seems to have answered your question so far..
The 4v supply is derived from the 8.5v +REG supply, which is generated on
the 81340 TX Low level amp / noise blanker board.
It is fed to the MIC connector via R34 ( 680 ohms ) on the 81456 Control
board making the short circuit current around 8mA or so.
I use a cheap call centre headset and boom mic assembly with my Omni V with
no problems at all.
The mic element is a condenser type with 2 terminals, I added an 18Kohm
resistor between the mic connector pin carryng the polarisation voltage and
the TX audio input connector pin.
This works fine for me.. there is no problem doing this, there is a DC
blocking capacitor befoe the input of the MIC preamp.
If you need more than a couple of mA, you could lower the value of R34
mentioned above, the +REG pass device is an MJE370 bolted to the chassis and
I suspect that you could draw 100mA if required.
The MJE 370 is a 3 Amp 25 watt device.
If you intend to connect outboard equipment to this supply, make sure that
you fit an RF choke in the MIC plug or as close as possible to the MIC plug.
It's best to use screened cable as well, to prevent RF getting into the +REG
supply and causing problems.
Hope this helps.
Paul MW0CDO.
Hope this helps
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