TIP on OLD STUFF-

[Garey Barrell]

Hi Bob -

Actually the Heath IT-28 is a little better for this use.

The current is limited by an internal 10K resistor.  So you start on
the 50V position (5 mA Max current) and wait for the "eye" tube to
open.  (The eye tube is fully closed at 2 mA current)  Then switch to
100V and on up, each time waiting for the eye to open before going to
the next step.  So far at least, I've found that a cap that is
"formable" will form just fine at 5-10 seconds per step.  The ones
that don't go that quick, don't!

Seems easier to me than trying to adjust the voltage for a specific
current, yet protects the cap and the IT-28 from excessive current.
Plus, if the cap should short, you don't bend the meter needle!!

The Spragues are perhaps better at measuring exact capacitance,
depending upon the calibration accuracy of each instrument, but if you
need to know the "exact" capacitance you can buy a DMM with
capacitance measuring capability for less than the cost of a Sprague.

My $0.02 .

73, Garey - K4OAH
Atlanta

----- Original Message -----
From: "Bob Nickels" <ranickel at MWCI.NET>

> > I certainly agree. However, if you have access to a variable B+
> voltage
> > source it's possible electrolytic capacitors can be
'reconditioned'.
>
>  A great tool for this purpose is one of the Sprague capacitor
checkers.
> Yeah, I know Heath made one but they left off an important piece:
the
> meter.  The Sprague TO-x series checkers have a variable DC voltage
> source that can be measured accurately with the meter, then you can
> switch it to monitor the current through the capacitor under test.
> Normally this is used to display the leakage current but it's ideal
for
> re-forming a cap - just slowly increase the applied voltage while
> keeping the current in the 2-5 ma range to allow the electrolyte to
> re-form without breaking down from excessive voltage or current.
>
> Handy for measuring capacitance too!
>
> 73, Bob W9RAN
>

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