[Boatanchors] Voltage Calibrator

[David C. Hallam]

Phil,

I have, of course, thought about what you suggest.  DC calibration of my 
VTVM which is a HP-410B is based on 1 VDC.  Back in the days before 
mercury batteries were banned, the PX-13 camera battery was an excellent 
source.  They were very accurately1.35V and held that value until very 
close to the end of their life.  As far a D cells go, they can be all 
over the place.  New ones are 1.6+ volts.  Maybe the alkaline ones don't 
age rapidly.

I suppose I will use a D cell with a 10meg pot across it and use my DVM 
to set 1 V

Another question:  What do you use for a AC standard?  I realize AC 
measurements don't generally have the accuracy as DC.  But, you have to 
get the DC calibration right first.

David
KW4DH

On 12/29/2011 11:44 AM, Phil wrote:
> How about a variable power supply, then put a DVM (digital Voltmeter) 
> whose accuracy you trust, in parallel with your VTVM across the power 
> supply.  Even a cheaper idea, depending on how high you want the 
> Voltage, if you're talking Voltages in the hundreds, snag the B+ from 
> a receiver, put a high value pot across it, then your parallel 
> VTVM/DVM across that.  MOST VTVM calibrations that I remember only had 
> one adjustment that affected all ranges, depending on the 1% resistors 
> in the divider to set the rest.  From what I remember, typically they 
> (Heathkit etc) used a NEW 1.5VDC D cell for calibration purposes and 
> had a mark on the meter for the "calibration point". Now with DVMs we 
> have much more affordable 'accurate' ways, and the usual DVM can be 
> read much closer than the analog dial of a meter.  So, it makes sense 
> to use the DVM as a "standard".
>
> Hope this helps you.
>
> 73 de Phil,  KO6BB
> http://ko6bb1.multiply.com/ (OTR Blog)
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>
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>
> On 12/29/2011 4:27 PM, David C. Hallam wrote:
>> What is a good DC voltage source that doesn't cost big bucks to use to
>> calibrate a VTVM?  I can't afford several hundred dollars for a piece of
>> test equipment with such limited use as a voltage calibration source.
>>
>> David
>> KW4DH
>>
>

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