[Elecraft] [K3] Smart Charger

[WILLIS COOKE]

You might take a look at the Jetstream JTPS35BCMA.  It includes volt and ammeters, connections for the rig plus low amp connections for accessories and a connection point for the battery.  The switch to battery is automatic when AC power is lost.  The artifacts are reasonable and liveable.  On the down side, the fan comes on with a 1 amp load and is noiser that I would like, but liveable.
 Willis 'Cookie' Cooke 
K5EWJ 




________________________________
From: Wes Stewart <n7ws at yahoo.com>
To: elecraft at mailman.qth.net; Julius Fazekas n2wn <phriendly1 at yahoo.com>
Sent: Tue, January 5, 2010 1:22:47 PM
Subject: Re: [Elecraft] [K3] Smart Charger

Julius, et. al,

My charger is actually a marriage of some commercial gear with a few tweaks.  The motivation for this was the absolutely horrible RFI from the switch-mode charger in my 5th wheel trailer.  It was so bad that when I had the trailer stored here at home the RFI would actually interfere with OTA TV, so you can imagine what it did to the ham bands.

Rather than reinventing the wheel, I used an Astron RS-35M for its case, metering, raw DC, heat sink and pass transistors.   Rather than building my own board, I married this to an A&A Engineering smart charger board, (http://www.a-aengineering.com/150PCAAppNotes.pdf) doing a little trickery to allow the use of a fixed current sense resistor while still having some adjustment of the max charge current.

The heart of this circuit is the UC3906 integrated circuit that is designed for just this purpose. (http://focus.ti.com/docs/prod/folders/print/uc3906.html)

I shopped the idea of an article about this to ARRL but they weren't interested, so I never completed any further documentation.

Wes  N7WS



--- On Tue, 1/5/10, Julius Fazekas n2wn <phriendly1 at yahoo.com> wrote:

From: Julius Fazekas n2wn <phriendly1 at yahoo.com>
Subject: Re: [Elecraft] [K3]  New K3 User and New Ham
To: elecraft at mailman.qth.net
Date: Tuesday, January 5, 2010, 10:17 AM


Wes,

Do share your 30A "smart charger". It's easy enough to find information for
lower current chargers, but less so for something in this range.

cheers,
Julius


      
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