[Elecraft] K3 Voltmeter calibration ...

[Fred Townsend]

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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