[AMRadio] Capacitance Meter/Tester

[Don Merz]

This is correct as far as I know. That is what the sencore meter does and what the Sprague TO- series of checkers do. Using the TO-series, becasue it has analog meters and adjustable volts, you can also use them to reform electrolytics. Just connect the cap, turn the voltage up until the ammeter reads 1ma, then watch as the current falls. When it gets down to about 0.1ma, turn the voltage up some more and repeat. Repeat until you are at the cap's rated voltage and leakage is zero or under 0.1ma. Voila--a good electrolytic where there was once a bad one. 

I have seen this same reforming trick automated in a homebrew circuit that I think used zener diodes. I am not sure of the design, but it would only allow the voltage to increase when the leakage was below some threshold like 0.1ma. Lazy-man's cap reformer! 
73 de N3RHT



________________________________
 From: Dave & Rita <k9dvl at comcast.net>
To: Don Merz <n3rht at yahoo.com>; Discussion of AM Radio in the Amateur Service <amradio at mailman.qth.net> 
Sent: Thursday, December 8, 2011 7:26 PM
Subject: Re: [AMRadio] Capacitance Meter/Tester
 
A test under voltage is the only way to test caps I use a variable power 
supply and an milliammeter
in series. with the cap. Keep increasing the voltage till I get to the 
rated voltage. There should be no
  current draw. I check value with a digital cap. meter. I am open for 
corrections.
                                                                                                                                          K9DVL Dave

On 12/8/2011 6:18 PM, Don Merz wrote:
> I like the sencore Z meter, model LC53. It measures leakage, inductance and capacitance. They go for $150-$200 on eBay. Another one that is capacitance only but is small and fast is the Doric 130A. That thing measures down in the pFs very accurately and has a simple adjustment for nulling out the lead capacitance. But no leakage test or anything else--it's a one-trick pony.
> 73 de N3RHT
>
>
>
> ________________________________
>   From: Jim Wilhite<w5jo at brightok.net>
> To: Mel Farrer<farrerfolks at yahoo.com>; Discussion of AM Radio in the Amateur Service<amradio at mailman.qth.net>
> Sent: Thursday, December 8, 2011 5:51 PM
> Subject: Re: [AMRadio] Capacitance Meter/Tester
>
> Mel, what is the model number of your Sencore?
>
> Jim/W5JO
>
>
> ----- Original Message -----
>
>
>
>> Don't have a Heathkit, but my SENCORE has been great for over 20
>> years.
>>
>> Mel, K6KBE
>>
>>
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