[Heathkit] meter protection

[Paul Kraemer]

How about using Shottky diodes. Their threshold is lower and they are faster 
than conventional silicon diodes. Or, how about germanium? Only 1/4 volt 
there
Paul K0UYA

----- Original Message ----- 
From: "Dennis Berry" <dennisberry at worldnet.att.net>
To: <heathkit at mailman.qth.net>
Sent: Wednesday, October 14, 2009 11:11 AM
Subject: [Heathkit] meter protection


>I have seen on several websites that advocate putting the back to back 
>diodes on a meter, which I am not rejecting as wrong, but I do have a 
>question.
>
> As I recall most of the Heath meters are about 1200 ohms and 200 uA 
> movements.  Wouldn't this indicate full meter movement is at 0.24V?  Do 
> diodes that conduct up to say 0.5V or 0.6V still protect the meter?  I 
> know it's better than a flashover voltage, but is 0.5V enough to still 
> damage the meter?
>
> Just trying to learn and understand, not pick on the method or Cal.
>
> Thanks in advance,
>
> Dennis, NU8S
>
>>  Message: 1
>>  Date: Tue, 13 Oct 2009 16:25:16 +0000 (GMT)
>>  From: C E <catman351 at yahoo.com>
>>  Subject: [Heathkit] SB-200 meter flashover/diode protection
>>  To: heathkit at mailman.qth.net
>>  Message-ID: <190179.86540.qm at web37103.mail.mud.yahoo.com>
>>  Content-Type: text/plain; charset=iso-8859-1
>>
>>  All:
>>  I noted Bill's comment on his friend's SB-200 meter flashover: "A friend 
>> of mine is looking for the meter (working) for his SB-200 - > apparently 
>> he had a flashover while tuning it up that took out his meter."
>>
>>  It would be cheap insurance to install a set of back-to-back diodes on 
>> your SB-200?multi-meter to mitigate the damage caused by such
>>  problems. One can replace diodes all day...meters, unfortunately, are 
>> another matter.? FWIW.
>>  Cal, N6KYR/4
>
>
>
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