[Elecraft] USB to Serial at 1500 watts Part II

[Joe Subich, W4TV]

> Could the electronics of the USB device be blown as the cable 
> acts like an antenna?  I don't want to make a stink over 
> this...just want to know peoples experience.

If you can induce more than 10V P-P of RF on the cable between 
the computer and the USB to serial adapter, it is theoretically 
possible that you could damage the USB UART.  The fault mode 
would most likely be reverse polarity (below -.5V) on the 
5V line (supply) or the input data lines (USBDP and USBDM). 

> Sill, I think it was RF for some reason.  Now then, I have 
> not had this happen to a simple RS232 cable from the Rig 
> to the Puter. 

The RS-232 data lines are inherently better protected for 
induced RF since RS-232 specified for +/-25V but operating 
levels are generally +/- 10V or so.  To cause over/reverse 
voltage issues you would need to induce 20V P-P on the cable. 

73, 

   ... Joe, W4TV 
  




> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Lee Buller
> Sent: Tuesday, August 04, 2009 7:32 PM
> To: Elecraft Reflector
> Subject: [Elecraft] USB to Serial at 1500 watts Part II
> 
> 
> The USB to serial port stopped working for good....when I was 
> on 80 meters.  The way I new is that N1MM Logger lost 
> connection and could not reattach to the K3.  I tried the K3 
> Utility...nada.  This only happened on 80 meters.  Yes, I 
> have a good RF ground.  Coax feed to the dipole.  Tuner.  
> etc.  All grounded (RF) together ... bonded ...to a ground 
> system that consist of a 8 foot rod in the floor of the 
> shack....bonded to the tower....bonded to three other 
> rods....bonded to the house.  Sill, I think it was RF for 
> some reason.  Now then, I have not had this happen to a 
> simple RS232 cable from the Rig to the Puter. 
> 
> Could the electronics of the USB device be blown as the cable 
> acts like an antenna?  I don't want to make a stink over 
> this...just want to know peoples experience.
> 
> Also,
> lets assume that RF can do weird thing...and everyone's set 
> up or circumstances are different...but I have done what the 
> "book" suggests.
> 
> Lee - K0WA
>