[Milsurplus] Need Meter for TV-7DU

[Bob Camp]

Hi

An excellent idea for the rest of us who have yet to to blow the meters 
on our TV-7's. Think I'll check mine ...

One small thing to add. You should be sure to use the right diodes. 
These days things like 1N4001's can have amazingly low leakage 
currents. Since they have a rating of an amp they are pretty darn tough 
to blow with the current present in a tube circuit. If you have some 
lying around I would suggest checking them to see how they do.

On the opposite end of the line, for the lowest leakage possible you 
want to use the emitter / base junction of an audio transistor. I 
forget exactly why but they have leakage levels at 0.3 volts that are 
about what a normal diode has at 0.05 volts. I seem to remember numbers 
in the nano amp region so either one should be fine on a 200 ua meter 
as long as the voltage does not get to high.

What's the resistance of a TV-7 meter  I wonder? It would be a shame to 
find out it's above 2K ohms and you forgot to put two diodes in series 
....

	Enjoy!

		Bob Camp
		KB8TQ


On Jul 23, 2004, at 9:27 PM, Joe Foley wrote:

> If you should happen to find a new meter be sure to
> put back to back diodes acrossed it to limit the
> chance of blowing the coils next time.  Like someone
> else probably did.
>
> Joe
>
>
>
>
> --- Dr M J DiGirolamo <DrD at 2020.com> wrote:
>> Hi Gang,
>>
>>    I purchased a TV-7DU from the ",,,bay-place" but
>> its movement is
>> shot.  Might someone have one laying around in a
>> parts unit or by some
>> other miracle?
>>
>>    All replies or suggestions are welcome.. thanks,
>>
>> Mike, W4XN
>> W4XN at arrl.net
>> Charlottesville, VA 22901
>>
>>
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