Wanted - AR-15 manual

[Garey Barrell]

Doug -

Tantalum caps have many advantages, but a high failure rate has become 
apparent in units run at close to their marked voltage ratings.  This is 
not an insignificant problem, since tantalums often fail shorted, and 
will become red-hot and even flame if the power supply doesn't shut 
down.  Designers now recommend doubling the operating voltage for safe, 
long term reliability.

If they are being used as filter capacitors or for other decoupling 
tasks, they can be replaced with electrolytic caps if size allows.  
Tantalums are much more stable and were held to much tighter tolerances 
than electrolytic caps when the AR-15 was designed, so if they are used 
in any sort of app that requires that stability and/or accuracy (timing 
circuit?) then use a voltage uprated tantalum.

73, Garey - K4OAH
Atlanta

Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>


> -----Original Message-----
> From: Heathkit Owners and Collectors List
> [mailto:HEATH at LISTSERV.TEMPE.GOV]On Behalf Of Doug Aab
>
>
> I haven't done any repair work in a long time. What is the best to
> replace the "tantalum" capacitors with?
>
> Thanks
>
>   

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