[Elecraft] [K3] Smart Charger

[Wes Stewart]

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