Re: Warm up time on old capacitor checker

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Ray von Postel <vonpostel-at-comcast-dot-net> 

John:
I have and use a Heathkit Condenser Checker Model C-3

Warm up time:  less than 15 seconds
Heathkit manual says:
"Resistors and controls generally have a tolerance rating of plus or minus 
20% unless otherwise stated.  Therefore, a 10,000 ohm resistor may test 
anywhere from 8,000 to 12,000 ohms.  The tolerance on condensers is 
generally even greater.  Limits of -50% to 100% are common for paper 
tubular types."
Notice that Heath makes no claim for either the precision or accuracy of 
the Capacitor Checker.

The checker I have reads 900 pf when measuring a 1000 pf  0.1% air 
dielectric standard capacitor.  So, at least on my checker, the reading is 
10% low on that scale.

Measurements on mica capacitors read as follows:

Nominal value:  0.1       mf    reads:  0.07 mf
                            10,000 pf               8,000 pf
                            20,000 pf             15,000 pf
                                  .01 mf                .005 pf
                                .015 mf              .0135 pf

This type of capacitor checker is not intended as a precision instrument 
but for servicing of vacuum tube circuits made up of  low precision 
components.  Notice that the reading I got for the standard capacitor was 
10% low and for the other capacitors they were all over the place.  You can 
figure that at least 10% of the error can be attributed to the capacitor 
checker and the rest to the capacitor being measured.

The checker does use vacuum tubes.  I suggest you check those as a first 
step.  One or more of them could be causing the slow warm up.  If that 
doesn't solve the problem then check the electrolytic capacitors for 
leakage resistance.

Replacement tubes and capacitors are available from several internet vendors.

Hope this helps

Ray


Tesla list wrote:
>Original poster: "John Richardson" <jprich-at-up-dot-net>
>Hi,
>
>This is directed to a few of the old timers out there.  I have an old
>hamfest Heathkit capacitor checker, and was doing some MMC readings last
>night.  It didn't even want to register anything on the green eye until it
>warmed up for at least ten minutes!  Is this normal for these things?  I'm
>used to new stuff, where results are instantaneous in this solid state age.
>Each of my 942 series caps measured out at .15 on this old thing, and a
>string of 7 measured about .02, even though it should be about .0143.  Do
>you think that this is accurate, or is my "Ten Minutes to Warm Up Heathkit"
>off a little bit?  I'm not disappointed if it is, as it was only fifty
>cents.  One more question, since this is directed at the old timers:  How
>old is our oldest list member?  I recall John Couture mentioning that he
>turned eighty five this last year.  It amazes me that the demographics of
>this hobby are so wide.
>
>Thanks,
>John Richardson
>
>