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Re: [Amps] Cal Lab

To: amps@contesting.com
Subject: Re: [Amps] Cal Lab
From: "Will Matney" <craxd1@verizon.net>
Reply-to: craxd1@verizon.net
Date: Sun, 23 Apr 2006 16:44:31 -0400
List-post: <mailto:amps@contesting.com>
All,

On those 0.01% resistors, I've been quoted anywhere from $15.11 to $22.00 each. 
That's why I said I'd like to find some at $7.00. Below are the $15.11 
resistors webpage link at Newark.

http://www.newark.com/NewarkWebCommerce/newark/en_US/endecaSearch/partDetail.jsp?SKU=35H5064&N=0

Best,

Will

*********** REPLY SEPARATOR  ***********

On 4/23/06 at 4:20 PM Will Matney wrote:

>John,
>
>Your right. When I wrote this, I was using an app called ESBcalc on my
>computer and I did it wrong. I was used to using my hand calculator, and
>this app is different in the way you do it. Sorry for the confusion. I
>need to read over what I type more often. Those resistors at 0.01% would
>be ok, and the same as a standard. At $7 a piece though, I need to find
>where to buy them that cheap. Most I have had quoted to me were way more
>than that.
>
>Best,
>
>Will
>
>
>*********** REPLY SEPARATOR  ***********
>
>On 4/23/06 at 3:02 PM W0UN -- John Brosnahan wrote:
>
>>>
>>> >0.01% resistors are pretty cheap. I use them in projects some times
>when
>>> >I want accuracy. Converting from pounds to USD, I reckon they are about
>>> >$7. Not exactly expensive and quite within the range of a ham to own a
>>> >few. Hence I somewhat doubt there is much point selling resistance
>>> >standards.
>>> >
>>>
>>>
>>>The 0.01% is a guaranteed value of resistors and standards, Most 
>>>standards though are actually closer than that by a good size amount 
>>>because they have been calibrated against a NIST traceable standard. 
>>>Most standard resistors were hand wound at one time. General Radio 
>>>and ESI both had resistor departments. The 0.01% resistors off the 
>>>shelf can vary up to that percentage. At 10k ohms, that's +/- 100 
>>>ohms. A standard that has been calibrated is actually much closer, 
>>>within 1 to 5 ohms at 10k ohms from what I have seen (9995, etc. 0r 
>>>0.0005%). A 5-1/2 digit DMM will read that easily. Over 99.9k ohms, 
>>>you need to go on up to a 6-1/2 or 7-1/2 digits to see the smaller 
>>>scale. A calibrated standard though will hold the guaranteed value 
>>>over the entire resistance it's capable of. If you placed in series 
>>>a bunch of off the shelf resistors together at 0.01%, I doubt you 
>>>could get that close.
>>
>>
>>A 0.01% 10K resistor can only vary by +/- 1 ohm and meet specs.
>>
>>1% = 1/100
>>0.1% = 1/1000
>>0.01% = 1/10,000
>>
>>1/10,000 of 10,000 ohms is 1 ohm
>>
>>--John
>
>
>
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