[Boatanchors] capacitor tester

[WA5CAB at cs.com]

And there is also the military ZM-3 and 3A, which I'm partial to, but not 
for any valid technical reasons.  It doesn't take up much more if any bench 
area than the TO-6A I previously had but probably weighs twice as much.  It 
needs a couple of minor mods to be useful for re-forming electrolytics.

In a message dated 12/7/2010 7:16:03 PM Central Standard Time, 
km1h at jeremy.mv.com writes: 
> I seem to have collected a few myself.
> 
> One that is often used is a 1939 Sprague Model 16 which was renamed the 
> TO-2 
> in 1941. They are fairly scarce, sorta big, but prices remain under $50. 
> They need a full recap and many resistors to become functional but modern 
> components can give 1% accuracy. What I like about it is that there is a 
> coarse step voltage switch which is fine tuned by a big wirewound pot 
> unlike 
> some later models which use just the pot which is a weak link and an odd 
> value. The 10W WW stepping resistors are still well under 1% tolerance. 
> Voltages up to 1000V are available which is why I like using it and it has 
> a 
> meter for voltage and leakage plus an eye tube for RC and insulation 
> resistance. It does not discharge electrolytics. That was fixed in a later 
> 
> model.
> 
> I also have a TO-4 and TO-6A with the latter reaching very high prices 
> thanks to the audiophools. Its an extremely good tester that isnt the size 
> 
> of some boatanchors..
> 
> And then there is the military ZM-11 which has enough controls on the 
> front 
> panel to satisfy an airline pilot. Naturally it does everything and they 
> are 
> generally in the $50-75 range.......so far.
> 
> I also used a 1941 Solar CE for awhile until the xfmr failed a few months 
> after restoring it. It has an RF oscillator which is tops for checking 
> micas 
> in their intended enviroment and at rated voltages. Cheap but not often 
> seen.
> 
> Carl
> KM1H
> 
> 
> ----- Original Message ----- 
> From: "The Pollacks" <rinkies at att.net>
> To: "'Dick KF4NS'" <kf4nsradio at verizon.net>; <boatanchors at mailman.qth.net>
> Sent: Tuesday, December 07, 2010 7:26 PM
> Subject: Re: [Boatanchors] capacitor tester
> 
> 
> >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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