[Milsurplus] Electrolytics

[Glenn Little WB4UIV]

While working as an engineer at a TV station, I replaced many hundreds 
of electrolytic capacitors.
They must have improved on their process as, for example, a 100 Uf 
capacitor would measure 90 something uF new, very rarely did it measure 
100 uF or above.
I guess the state of the art got to the point that they could very 
accurately predict the actual capacitance.
I guess it would save a penny or so on each part not having to use 
excess aluminum to ensure the rated capacitance.

Just my experience.

Glenn

On 8/20/2025 11:15 AM, Charlie L. wrote:
> Thanks Jim and David for the comments.  One thing about electrolytics is 
> that our old units seem to have a tolerance rating of -20/+80% of 
> indicated value. Most folks want to replace, say a 40uf at 450VDC, with 
> the same thing, and end up paying $10 or more for a name brand, while 
> you can find the 39uf at 450V and higher for just a few dollars.  A lot 
> of the smaller caps are also abundant  with a 630VDC rating at an 
> inexpensive cost, compared to being a purist and wanting .1 at 600 for $5 
> where the .1 at 630V  can be in the 50 cent range.  When you use Newark or 
> Mouser, a big giveaway when you are putting in the part value in the 
> filter window and you see three 40uf listed and 72 39uf listed, you know 
> the 39's will be cheaper with a greater voltage range selection.  The 
> 20uf cap was ubiquitous in just about any gear years ago, Newark has 3 
> choices for a 20uf and 28 for an18uf, well within the acceptable  
> tolerance.  I thought when Newark started selling leaded resistors for a 
> fraction of a cent each, that they were dumping stock,  as everything 
> seemed to be going to SMD style, but maybe that is not the case.
> 
> Charlie in NC
> 
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI, FRA, NRA-LM    ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"