[Elecraft] Neat K3 Video! - K3 Amp interface questions

[Jerry Flanders]

At 10:32 AM 12/3/2007, Ian White GM3SEK wrote:
<SNIP>The problem was simply that, on the issue of compatibility with 
existing technical standards in the market, nobody picked up the ball.

><SNIP>
>
>3. Reverse logic in the band data output. Again, this 4-bit encoding 
>was originated by Yaesu, and has since been adopted and extended by 
>a range of third-party providers. The standard band data output is 
>TTL, logic 1 = 5V, logic 0 = 0V.
>
>The K3 uses industry-standard band encoding, but the output 
>interface is not standard. Use of open-drain pulldowns in the K3 
>means that existing non-Elecraft band data  interfaces will not work 
>without some modifications and a user-provided positive supply rail.

Thanks for mentioning this, Ian. I hadn't picked up on this before. 
One of the major reasons I ordered a K3 was because I assumed the 
automatic band selection feature on my Quadra would work directly 
with the K3 after I wired up a new cable.

I am presently using a method in which my PC reads the rig freq and 
generates band-data signals for the amp ( 
http://www.ab4oj.com/quadra/w4uk.html or 
http://mywebpages.comcast.net/rwilliams309/QUADRA_interface.html ). 
This works OK, but always requires the logging computer is on and 
that the program is running.

Are there any existing devices that would work with the K3 band-data 
interface as-is? Anybody know of such?

Ian, if this is fixable within the K3, will it require a hardware 
change or can it simply be inverted in software?

Jerry W4UK