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Re: [TenTec] Centurion 422

To: tentec@contesting.com
Subject: Re: [TenTec] Centurion 422
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 15 Dec 2010 20:13:15 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
I can't tell from the downloadable manual, but all my life 1 ma meters 
have been more like 50 ohms if quality meters.

3.3 volt zeners may induce some modification of the meter reading 
because they tend to have a soft knee, not going into strong conduction 
at low current.

73, Jerry, K0CQ

On 12/15/2010 7:27 PM, pfizenmayer wrote:
> Nope - the meters drop 2.38 volts at 1 ma - 2380 ohms and are fed from
> fairly large series resistors so the 3.3 volt zeners are fine - in addition
> the forward diode tends to damp the meters some as they are pretty undamped.
> Hank K7HP
>> Most meter coils drop less than 0.1 volt so 3.3 volt zener's aren't much
>> protection. Better to use 1N4001 single junction silicon diodes, two in
>> parallel opposite polarity. They won't leak any current until the drop
>> gets up to about .55 volt.
>> 73, Jerry, K0CQ
>>> 73 de hank K7HP
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