[R-390] More C709 info

[DW Holtman]

Good Morning,

If you are thinking about using sand state, AADE makes an excellent 
cap/inductor checker. It is relatively inexpensive and very precise, 
very reliable. I use mine all  of the time for around 3 years, with no 
problems.

For testing cap breakdown I use a Military AN/PSM-2-A. It is a Megohm 
meter (meger). It has a crank handle with two leads. Hook up the cap in 
question and crank, it shows the resistance or breakdown of the cap. 
Paper Caps such as Black beauties, commonly show resistance of under 1 
mega ohm, which is clearly showing breakdown inside the cap. New plastic 
caps such as orange drops show in excess of 150 mega ohms, mica's show 
infinity.

Cranking the handle around 1 turn a sec, produces the max out, which is 
around 500 Volts, which is good for many caps. Slowing down the cranking 
speed, reduces the voltage, it is easy to crank out 200 or 300 volts for 
lower voltage caps. One caution, have a wire with allagator clips on the 
ends to short out the cap after testing, a good cap will hold it's 
charge real well, as I have experienced this.

It can also be used for testing primary transformer windings before 
applying power, coax cables etc. They are available on ebay now and 
them. I bought mine for $10.00 and glad that I did.

73's
DW Holtman
WB7SSN




n4buq at knology.net wrote:

>On Wed, 3 May 2006 00:10:17 -0400 (EDT), John Lawson <jpl15 at panix.com> 
>wrote :
>
>  
>
>>On Tue, 2 May 2006, Barry wrote:
>>
>>    
>>
>>>doubles in amplitude.  Is this expected behavior or is the capacitor 
>>>      
>>>
>most
>  
>
>>>likely leaky?
>>>      
>>>
>>  One of my very-frequently-used bench instruments is a little (old:50s) 
>>Cornell Dubilier capacitor bridge - with a tuning eye indicator.  Checks 
>>from a few 10s of pF to about 100 mF - you know the general type.
>>
>>  It was on the "FREE" pile at a swapmeet some years back, and it cried 
>>    
>>
>out 
>  
>
>>to me, so I rescued it.  I have several much newer, more 'sophisticated' 
>>devices to do this - but for vintage tube gear - the little CD bridge 
>>    
>>
>does 
>  
>
>>an easy, perfect job every time - and puts enough voltage accross a cap 
>>    
>>
>to 
>  
>
>>"wake it up"...  ;}
>>
>>   So my oblique answer to your Question above is: "Ellifino, whyncha 
>>checkit an see?" And to do that - there are a lot of older, cheaper 
>>capacitance bridges and meters out there - I get so much use out of mine 
>>it's amazing. Can't bitch over the 'price', either...
>>
>>
>>Just another 200 millidollar for a Tuesday evening...
>>
>>
>>Cheers
>>
>>John  KB6SCO
>>    
>>
>
>I've been wanting something to check capacitors for a long time, but just 
>haven't found anything I'm willing to pay what the seller wants.  I've been 
>outbid on a few, but just haven't found the "right" one yet.
>
>Hopefully I'll get to go to our big hamfest this year (I've had to miss it 
>the last two years!).  Maybe something will turn up there.  My 'scope is 
>just about to the point of being nothing more than a "relative indicator".  
>I need a much better 'scope too, but those get expensive in a hurry!
>
>I'm going to get a 510pF 5% today and see what effect it has on the circuit.
>
>Thanks,
>
>Barry - N4BUQ
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