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Re: [TenTec] Scout S-Meter Fail (nitpick follow-up)

To: tentec@contesting.com
Subject: Re: [TenTec] Scout S-Meter Fail (nitpick follow-up)
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 15 Nov 2010 15:43:08 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Most analog meters are linear. But they can be made with nonlinear 
results, like the movement for a thermocouple ammeter has varying pole 
piece gaps to vary the sensitivity as the armature moves.

Generally because of a logarithmic control of the gain controlled stages 
an S-meter showing AGC voltage comes up logarithmic with a linear movement.

If you don't like the linear display after you have tried it, you can 
modify the voltage going to he input with biased diodes to load it 
differently at different voltages.

73, Jerry, K0CQ

On 11/15/2010 3:14 PM, Bill Acito W1PA wrote:
> I plan to replace the failed s-meter on my Scout with a LM391X LED bar graph. 
> The chip is available in three versions -- linear, log, and VU  --3914, 3915, 
> 3916)
>
> Are all analog meters linear? (should I be replacing this with a LM3914 
> (linear) display IC)
>
> Remember, it is replacing just the meter, not the entire s-meter circuit 
> (which I assume displays a log measurement)?
> _______________________________________________
>
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