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Old 06-04-2014, 10:19 PM
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Winky Dink Winky Dink is offline
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Heathkit IT-28 Cap Checker Question(s)

A few weeks ago I picked up a Heathkit IT-28 Capacitor Checker. I replaced nearly all of the capacitors and most of the resistors before I powered up. But I left an untrimmed resistor lead shorting the voltage control switch which wasn't so bad--only destroyed a 1-Watt resistor and a fuse and the smoke alarm didn't even go off. Beyond that the only hiccup was that the "power factor" potentiometer needed a good dousing with QD Electronic Cleaner.

I made that sound simple and easy, but it was actually a two-week struggle for me. Nevertheless, I'm now joyfully testing a pile of recycled electrolytics which I was previously afraid to use.

But!...the manual addresses the need to calculate a power factor to compensate for serial resistance in electrolytic capacitors. The manual is dated 1968. Is this an still an issue with modern capacitors? I've been ignoring the power factor and getting accurate results on capacitor values.

Also, the IT-28 has settings for (1) paper/mica/etc., (2) electrolytic, and (3) min. 'lytic ( miniature electrolytic). These settings are linked to the range settings, but it seems that the assumption is that paper is low uF, electrolytic is high uF, and miniature electrolytic is somewhere in between. Is there any need for the "min. 'lytic" setting? For that matter, are the electrolytic settings only because of the power factor control?

I'd appreciate some advice because I really don't want to figure out how to use the power factor.

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