[AMRadio] Capacitance Meter/Tester

Thu Dec 8 20:27:09 EST 2011

The thing the Sprague does is check insulation resistance.  That is something very valuable for checking old silver mica and paper caps.  Those things can fail and you won't know until voltage is applied.

I am not sure if the Heath and Sencore do, but can be valuable.  Rick if you don't want to wait then Almost All Digital Electronics sells a very nice, accurate meter that gives capactiance and inductance. Search for aade on the web and take a look.  Then,in your own time, look for one of the others.

Jim/W5JO

Don Merz <n3rht at yahoo.com> wrote:

>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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