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Re: [RFI] Big Farad versus Hybrid Caps?

To: Michael Keane K1MK <k1mk@alum.mit.edu>
Subject: Re: [RFI] Big Farad versus Hybrid Caps?
From: kd4e <doc@kd4e.com>
Reply-to: doc@kd4e.com
Date: Fri, 19 Jun 2009 15:06:30 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I just used "big Farad cap" as a nickname because I figured 
everyone
would know to what I was referring.

I need to manage the load-spikes from a SSB modulated HF signal
through a solid state RF amp.

Rather than two $190. 90lb batteries I can use one large 
battery and
one Hybrid cap and in my intermittent load application be in 
good
shape.

Yes?

> I'm assuming that a "big Farad cap" is a colloquial name for an electric 
> double layer (aka electrochemical) capacitor 
> <http://en.wikipedia.org/wiki/Electric_double_layer_capacitor>
> 
> AFAIK, Hybrid® Capacitors are a product line of Evans Capacitor 
> (<http://www.evanscap.com>). Hybrid® caps have a lower Equivalent Series 
> Resistance (RSR) and somewhat better "high frequency" characteristics 
> than electrochemical caps.
> 
> A typical electrochemical capacitor behaves as a capacitor only at 
> frequencies < 1 Hz
> 
> An  electrochemical capacitor will help with battery "sag" that occurs 
> over a timescale of seconds.
> 
> However, an  electrochemical capacitor will not provide much filtering 
> for load variations that are happening at audio frequencies (like voice 
> peaks). To filter out audio peaks you'd want to use a big electrolytic.
> 
> 73,
> Mike K1MK

-- 

Thanks! & 73, doc, KD4E
FS/Swap/Wanted: http://kd4e.com/swapn.html
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Personal: http://kd4e.com
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