Elecraft

KX3 VFO B Alternate Display ?

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Phil Hystad-3

KX3 VFO B Alternate Display ?

On the KX3 VFO B Alternate Display you read Time, Power Supply Voltage, Battery Voltage, and so forth.

So, my question is regarding the BT (Battery Voltage) display. I assume that this reads the same as the external power supply voltage level (PS) if there are NO batteries in the battery holder.

I never paid too much attention to this before and I have had batteries installed almost from the time I put the KX3 together so I have not noticed this before.

So, can someone confirm that if no batteries are used that BT shows the same reading as PS? I can understand how this might make some sense but I think I would prefer that BT show zero volts (or, N/A) or something if no batteries are installed.

Thanks

73, phil, K7PEH

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Rich Heineck

Re: KX3 VFO B Alternate Display ?

Phil,

That is correct. The battery '+' and external supply '+' are connected
together. The voltage at the battery's negative terminal is measured
and subtracted from the voltage at the '+' side. So with no batteries
installed, 0V would be read at the batt '-' side. And when no external
supply is connected, BT and PS will also read the same. This is all
related to how the battery and external supply are isolated from each
other through the diode 'OR-ing' circuit that allows the higher voltage
of the two to power the radio.

73,
Rich AC7MA

On 07/15/2013 09:33 PM, Phil Hystad wrote:

> On the KX3 VFO B Alternate Display you read Time, Power Supply Voltage, Battery Voltage, and so forth.
>
> So, my question is regarding the BT (Battery Voltage) display. I assume that this reads the same as the external power supply voltage level (PS) if there are NO batteries in the battery holder.
>
> I never paid too much attention to this before and I have had batteries installed almost from the time I put the KX3 together so I have not noticed this before.
>
> So, can someone confirm that if no batteries are used that BT shows the same reading as PS? I can understand how this might make some sense but I think I would prefer that BT show zero volts (or, N/A) or something if no batteries are installed.
>
> Thanks
>
> 73, phil, K7PEH
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Jeff Herr

Re: KX3 VFO B Alternate Display ?

Hey Rich!

got a schematic snippet to include?

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Rich Heineck
Sent: Tuesday, July 16, 2013 8:09 AM
To: [hidden email]
Subject: Re: [Elecraft] KX3 VFO B Alternate Display ?

Phil,

That is correct. The battery '+' and external supply '+' are connected
together. The voltage at the battery's negative terminal is measured and
subtracted from the voltage at the '+' side. So with no batteries
installed, 0V would be read at the batt '-' side. And when no external
supply is connected, BT and PS will also read the same. This is all related
to how the battery and external supply are isolated from each other through
the diode 'OR-ing' circuit that allows the higher voltage of the two to
power the radio.

73,
Rich AC7MA

On 07/15/2013 09:33 PM, Phil Hystad wrote:
> On the KX3 VFO B Alternate Display you read Time, Power Supply Voltage,
Battery Voltage, and so forth.
>
> So, my question is regarding the BT (Battery Voltage) display. I assume
that this reads the same as the external power supply voltage level (PS) if
there are NO batteries in the battery holder.
>
> I never paid too much attention to this before and I have had batteries
installed almost from the time I put the KX3 together so I have not noticed
this before.
>
> So, can someone confirm that if no batteries are used that BT shows the
same reading as PS? I can understand how this might make some sense but I
think I would prefer that BT show zero volts (or, N/A) or something if no
batteries are installed.

>
> Thanks
>
> 73, phil, K7PEH
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html
>

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Lyle Johnson

Re: KX3 VFO B Alternate Display ?

Jeff,

The complete KX3 schematic set, including the KXBC3, is on the Elecraft
web site.

73,

Lyle KK7P

> Hey Rich!
>
> got a schematic snippet to include?

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