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Re: [TenTec] Orion2 Problem with indication of the analog meter

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Orion2 Problem with indication of the analog meter
From: "Bob Henderson" <bob@5b4agn.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 14 Sep 2006 13:12:52 -0000
List-post: <mailto:tentec@contesting.com>
Bill

I'm not sure this explanation holds water.

The 8 bit D to A will reduce that 1/10th dB resolution from the precision 
arithmetic to 114/256 dB or just better than 1/2 dB.   Unless the S-meter 
movement is really bad, there's something else at work here.

73

Bob, 5B4AGN

> **********************************************
> At times my S-meter doesn't seem very accurate, why is that?
>
> Precision arithmetic is used to calculate the S-meter measurements
> and the (digital) output is extremely
> accurate. The digital S-meter readings can be read over the serial
> port using the ?S command. The
>  s-meter numeric precision is roughly 1/10 of a dB.
>
> The analog meter is the analog representation of the digital S-meter
> result. The meter accuracy is affected
> by two things. First, the meter is electromechanical and subject to
> manufacturing and environmental
> variations. Second, the DSP/Logic board drives the meter through an
> 8-bit Digital-To-Analog converter
> which limits the meter to 256 steps.
> ***************************************************
>
>         The PWR control seems to be fairly accurate
> except at the lowest settings.  The minimum power I
> can set on my Orion is about 4 Watts at a setting of 1.
>
>                                 73,  Bill  W4ZV
>

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