[time-nuts] Electrolytic Capacitor Question

Bob Camp kb8tq at n1k.org
Sun Nov 9 22:15:41 EST 2014


The high grade aluminum electrolytics and the tantalums will look quite different on a network analyzer as you sweep them from 100 KHz up The ESR of the electrolyitcs will be significantly higher and they may go inductive. The tantalum caps (for what ever reason, I’ve seen more than one theory) stay capacitive for quite a ways. How far that is depends of course on the lead lengths and capacitor value. This is all based on solid tantalum caps. I’ve never put a wet slug on a network analyzer and seen what it does going up to a few hundred MHz. 

I last did the test on the tantalums in 1976, I’d bet they still look about the same. I’ve tested electrolytic from various generations and seen data from others on them. I do not have data on the exact part number you are looking at. 

Next up would be reliability. Even the high end electrolytic scare me more based on what I’ve seen fail than the tantalums. I’ve killed my share of both, but far more electrolytics. 


> On Nov 8, 2014, at 6:32 PM, Perry Sandeen via time-nuts <time-nuts at febo.com> wrote:
> List,
> OK everybody, let’s not get our pacemakers wound up<G>
> The problem. (Long Intro)
> I have about 15 pieces or so of older HP test equipment.
> 3586B, 5370B, 5335A to name a few.  Because of their age of 20+ years a few have failed and need repair. I
> have decided to go on a wholesale electrolytic capacitor replacement on all of
> them. (Mouser will be able to declare an extra dividend)
> For all the *standard* types I’ve chosen mostly Panasonic
> 105C 10,000 hour caps. So far, so good.
> Now I come to the issue of the wet-slug tantalums that were
> used.  At the time of manufacture, these
> were the best and most expensive low voltage electrolytics available.
> The question is: can one replace the tantalums with the high
> grade (105C) Panasonic or Nichicon capacitors with an equal or higher
> capacitance value?
> Even using the *tear drop* new replacements one is looking
> at very heavy $$$.
> Regards,
> Perrier
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