[Elecraft] K3 Voltmeter calibration ...

[Joe Subich, W4TV]

Fred,

Diode, polyfuse, etc. does not matter.  There should be a calibration
routine so it can be set correctly.  I remember setting it when this
K3 was assembled but can not find the procedure in the current manuals.

What is the calibration procedure?


73,

    ... Joe, W4TV


On 11/24/2015 3:34 PM, Fred Townsend wrote:
> Joe check your schematic and you will see there is both a polyfuse and a
> diode in series with the K3 front panel. The 100w PA pulls off its current
> ahead of the fuse and diode so using the front panel is not indicative of
> the voltage of the current going to power amp. Hang a voltmeter on the APP
> if you want accuracy. Incidentally the polyfuse will permanently change
> cold value after interrupting for the first time so there is another
> variable.
> 73
> Fred, AE6QL
>
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Joe
> Subich, W4TV
> Sent: Tuesday, November 24, 2015 9:31 AM
> To: Robert Nobis; Elecraft
> Subject: Re: [Elecraft] K3 Voltmeter calibration ...
>
>
>> You could easily drop 0.2 volts in the cable depending how long it
>> isand the gauge of the wire.
>
> Not in six feet of #10 wire at 1.5A.  Even if it were #12 the voltage drop
> should be less than 0.03V (1.62 Ohms/1000 feet for #12).
>
> 73,
>
>      ... Joe, W4TV
>
>
> On 11/24/2015 10:39 AM, Robert Nobis wrote:
>> Joe,
>>
>> How long is your power cable from the RS-35A to your K3, and what gauge
> wire is used?  You could easily drop 0.2 volts in the cable depending how
> long it is and the gauge of the wire.
>>
>> 73,
>>
>>
>> Bob Nobis - N7RJN
>> n7rjn at nobis.net
>>
>>
>>> On Nov 24, 2015, at 08:06, Joe Subich, W4TV <lists at subich.com> wrote:
>>>
>>>
>>> OK, I'm sure I am overlooking something simple but I can not find (or
>>> remember) how to calibrate the voltage display in the K3.
>>>
>>> I had to repair one of my Astron RS-35A power supplies for the first
>>> time in 30 years (one of the diodes shorted) and when I put it back
>>> on line I decided to double check the K3 Volts display against the
>>> actual output of the supply.  The K3 is reading about 0.2V less than
>>> the supply voltage.
>>>
>>> I've been over both the K3 Owner's Manual and the K3 Assembly
>>> Instructions but can't find any reference to calibrating the voltage
>>> display.
>>>
>>> 73,
>>>
>>>     ... Joe, W4TV
>>>
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>>
>>
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