[ARC5] Re-capping

[Bob Macklin]

The leakage test switch on the C-3 is spring loaded and you have to hold it 
in position.

On the IT-11 and IT-28 the leakage switch is not spring loaded. You can 
start with a low voltage setting and let it cook a while before moving to 
the next higher voltage. That's what I like most other then it takes up a 
little less space on my bench.

You can usually get ether the IT-11 or IT-28 on eBay for $30 or less.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Richard Schumann" <richardschumann at comcast.net>
Cc: <Arc5 at mailman.qth.net>
Sent: Sunday, March 06, 2011 1:38 PM
Subject: Re: [ARC5] Re-capping


> On 6 Mar 2011 at 12:46, Richard Schumann wrote:
>
>> Well, all this talk about checking capacitors has motivated me to
>> purchase an inexpensive unit that will do the job.
>>
>> For those of us on a 'Harbor Freight' budget, do they or another
>> source have a reasonably priced DMM or something accurate enough to
>> get the job done?
>
> Unfortunately, not to my knowledge.
>
> What you need for this kind of work is some sort of instrument that can
> apply the rated voltage to the capacitor then measure any resulting 
> leakage
> at that voltage.
>
> Over the years, there were many, many such instruments built and sold by
> many companys.
>
> Sprague, for instance, sold one, and upgraded it continually, under the
> name of Tel-Ohm-Mike, which was a very good one.
>
> The models were TO-3 through TO-6, as far as I know.
>
> IMHO, the best of the bunch was the TO-5, and this particular model
> always goes for a fairly high price on eBay.
>
> Manuals for these are available on BAMA.
>
> I use two different Heathkit C-3 units, one at work, and one at home, 
> which
> I rebuilt some time ago and wrote an article that was published in 
> Electric
> Radio magazine detailing both the C-3 itself, how to rebuild it when
> necessary, and how to use it properly.
>
> The C-3 and its ilk not only measure capacitance (somewhat crudely, but
> accurately enough, i.e. within 10% in most cases), resistance, and leakage
> in capacitors, both paper and mica, and electrolytic, but they also 
> measure
> "Power Factor" in electrolytics, and can be used to reform electrolytic 
> caps.
>
> Knight, Eico, and Lafayette, among others, had similar models.
>
> The latest Heathkit version, as mentioned by Bob Maclin here, was the IT-
> 28, which was also sold as the IT-11 under a different color scheme.
>
> This is an excellent instrument, easily available from eBay at regular
> intervals.
>
> Some of those need to be rebuilt, but basically, they are perfect for this 
> kind
> of work.
>
> There is a fellow, a ham, who sells a kit on eBay to make the older 
> Heathkit
> C-3 types as capable as the IT-28. I bought two of those kits from him.
>
> One very interesting feature of the C-3 and its predecessors and some
> subsequent models, is that it uses both the 1626 triode VFO tube from the
> ARC-5 transmitter (as a rectifier) and the 1629 eye-tube as the indicator.
>
> That kit I mentioned above re-configures the 1626 into an amplifier, and
> does other things to the C-3 to bring it more up to date.
>
> Most of these units have the capability of reforming electrolytic caps 
> too.
>
> The Sprague units also can measure transformer turns-ratios.
>
> Ken W7EKB
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