Try Batteriesamerica Tom.  Website; batteriesamerica.com
I think his T H F 6A replacement is under $50.

Pat, K9JAU At 08:30 PM 11/26/2003 -0500, you wrote:
>Hello all.
>
>Well, I finally talked to a Customer Support Rep from Kenwood today about my
>problem with the lythium ion battery pack for my THF6A, and he gave me the
>answer that some of us suspected.
>
>Specifically, you may recall that I tend to use the THF6A as a base unit,
>most of the time.  I run it with a 2-amp regulated power supply.  In line
>with my earlier experience with other HT's, I simply did this with the
>battery pack still on the radio, thinking that no harm should be done, since
>when I turn the power supply off with the rig connected, the rig shuts off
>as well.
>
>The Kenwood rep said that, although in many other cases like this, I'd be ok
>with this strategy, the THF6A is the first Kenwood HT that has been designed
>to charge the battery while it is connected to an external DC power source,
>such as a car battery or DC power supply.
>
>So, in short, I guess I basically cooked the battery pack while running the
>unit as a base station on a long-term basis via the external power supply.
>
>So, now that I apparently am looking at replacing my lythium ion battery
>pack, my next question is where can I get one at a reasonable price.  I know
>that Kenwood sells one for $79, but I have seen Maha packs for as low as
>$49.95, I think.
>
>Any help here would be appreciated.
>
>In the meantime, I'm now running the THF6A as a base unit by putting the
>empty extra battery case for double A. batteries on the unit.  This is what
>the guy from Kenwood suggested.
>
>Let's all learn from my experience--I hope it will help some folks not make
>the same mistake I did.
>
>Best 73 from Tom Behler:  KB8TYJ