[Elecraft] Re: 10/100 BaseT vs USB

[Mike Butts]

On Tuesday 16 July 2002 07:07 pm, Jessie Oberreuter wrote:
> On Tue, 16 Jul 2002, Bill Coleman wrote:
> > Fooey. I've got unsheilded 100 BaseT cables running all over my house,
> > and I have yet to hear any RFI from that system. And they run a heck of a
> > lot faster than USB does.
>
>      Heh, 10/100-BT cables are balanced feed twisted pair -- wired
> correctly, they don't radiate much and can accept a lot of interference.
> Wired incorrectly and, well, even my 706 will hear the packets :).  I used
> to take down a neighbor's network every time I keyed up -- turned out to
> be a long, mis-wired net cable...  IIRC, USB is semi-balanced: the data
> goes through push-pull, but much of the signaling is common mode.

Good point, Jessie.  And yes, Bill, I have lots of ordinary 100 BaseT here
in my shack too.  Coax up to the top of the dipole, so RFI isn't too much
of a problem.

I should have been clearer, sorry.  My concern is fast digital signals 
*inside* the K2's box.  The PICs they use in K2 are sweet because they're
self-contained, just the control lines and sometimes a short and easily
shielded 4 MHz resonator signal are on the PCB.  Wayne and Eric took 
special care with what's on the KIO2 like I said before, to keep even an
audio-frequency RS-232 interface RF quiet inside the box. 

Controlling the K2 is a very low-bandwidth undemanding application,
nothing remotely like the printer, scanner and camera that use my USBs.
So USB in K2 adds no more function over RS-232 besides convenience.

If there was an inexpensive PIC with a built-in USB controller to keep all 
the noisy PIC-USB interface stuff inside the chip, then *maybe* a "KUSB2" 
could replace the KIO2 card and still be quiet.  I didn't see one in a quick
google search. 

There'd still be some fast digital signals between the PIC/USB and its
USB cable buffer chip.  It would surely cost more than KIO2, and require a 
software driver, Windows, Mac and Linux support, etc.  Maybe it would 
end up costing as much over KIO2 as an RS-232/USB adapter, which 
I've seen around $40.  

As long as there's an off-the shelf solution available for USB, I'd just as
soon see Wayne and Eric apply their unique talents to radio stuff.
(You guys are surely reading the mail here.  Pretty smart of you to get 
all this free market research and product engineering!  We'd love to hear
your thoughts on USB.)

  73 de KC7IT