[Boatanchors] capacitor tester

[The Pollacks]

I am nowhere near a technical expert, but 4 cap checkers have followed me
home and never left. (I've had others of the same model and sold them.)
Here are my observations, and results that I've had.

First, the IT11 and IT28, as you note, are identical except for the cabinet
style. I have both. I also have one of the C3 style, but so old that it
doesn't even have a model number.  It's the old Heath light greenish brown
with the maroon trim.  All of these work almost exactly the same way, and
are about equal in accuracy, which is to say plenty close enough for our
type of work, I think.  The drawback to them is not in measuring and testing
caps, but in re-forming electrolytics, one of my common uses.  The eye will
open when the cap is formed enough so that a sufficiently small amount of
current leaks to show that the cap is formed and/or ok.  Usually, to form
the cap, I start at about 25% of the rated voltage, and increase the voltage
slowly as the eye opens, which can take an hour or so, but usually much
less.

The problem comes into play when testing/reforming high capacitance high
voltage caps.  The allowable leakage current is high enough to keep the eye
from opening even in a new capacitor.  The manual gives the formula for
determining allowable leakage current, and a VOM in series with the cap will
tell you if the cap is in spec.

The Sprague unit (I have a TO3 or 4, I forget which!) has a meter that can
be switched in to read leakage current, as well as actual voltage, which is
varied by a rheostat continuously, rather than a switch with discrete
voltages.  I don't know how much they go for, and I seldom see them for
sale, although I haven't searched.

Advantage of the Heathkits:  They're small and take up little room on the
test bench shelf.  Disadvantage:  Above, with big caps.

Sprague:  Only disadvantage to me is that it takes up too much room.  So, I
have a Heathkit IT-28 on the bench, and the Sprague on reserve when I need
it.

Hope this helps!

Ron K2RP 

-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
[mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Dick KF4NS
Sent: Tuesday, December 07, 2010 3:38 PM
To: boatanchors at mailman.qth.net
Subject: [Boatanchors] capacitor tester

I have a desire for an improved design tester for my bench. I have 
looked at the Heathkit IT-11/28 (don't see the difference between 
them) as a possibility and maybe Sprague TO-5/6A but they are so 
costly. I am now using the Heathkit C-3 which has been completely 
refurbished using Ken's (W7EKB) notes, with new parts and is in mint 
condition in functionality and appearance, but would like an upgrade.

I will buy one of those Russian ESR meters when I save somemore 
greenbacks.  Please let me know your opinions and whatever you might 
have for sale. Anyone interested in the C-3 let me know.

73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow! 

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