KX-1 Voltage Display

[david dorrance]

Hi all,

I am building KX-1 SN 1625.  Concerning Alignment and
Testing-Part 2, page 44 of the manual, testing
approxiomate power supply or battery voltage:  The
display registers 12.2/3 volts; my DMM  across the
battery terminals registers 12.60 volts.  

Is this discrepency with the definition of
"approximate"  or do I have a problem?

Dave WA6YSO


 
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[Mike Morrow-3]

David wrote:

>display registers 12.2/3 volts; my DMM  across the
>battery terminals registers 12.60 volts.  

The KX1 MPU doesn't sense battery or power supply output voltage until it has passed through reverse polarity protection diode D2 or D3 (1N5817).  At the current that your KX1 is drawing, there will be about a 0.3 to 0.4 voltage drop across the 1N5817.  Your KX1 voltage display should be lower by that amount than the actual voltage being fed into the KX1 power connector.  It looks like your display is right on the money.

Mike / KK5F
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[Don Wilhelm-3]

Dave,

Your meter is reading the voltage outside the KX1 while the KX1 is
displaying the voltage after the series protection diode, hence the slightly
lower voltage.  Yes, you can expect about a 0.3 volt drop.

73,
Don W3FPR

> -----Original Message-----
>
> I am building KX-1 SN 1625.  Concerning Alignment and
> Testing-Part 2, page 44 of the manual, testing
> approxiomate power supply or battery voltage:  The
> display registers 12.2/3 volts; my DMM  across the
> battery terminals registers 12.60 volts.
>
> Is this discrepency with the definition of
> "approximate"  or do I have a problem?
>
> Dave WA6YSO
>

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