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


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[Joe Subich, W4TV-4]

> 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: [hidden email]
> [mailto:[hidden email]] 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
>

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[Jim Brown-10]

On Tue, 4 Aug 2009 16:32:26 -0700 (PDT), Lee Buller wrote:

>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.

Just because you're using the USB device in a ham station, don't
assume that every possible failure is the result of RFI. A lot of
this stuff is made cheaply, and it can fail. Over the years, I've
had to replace several name brand WiFi adapters and Ethernet
switches because they stopped working. One of my colleages in the
pro audio community has had the same problems.

My favorite solutions for rig control all involve a REAL serial
port. 1) An older computer with a port.  2) A port replicator that
gives me the port. 3) A PCMCIA card that gives me the port. About
five years ago, I bought a 2-port Quatech card that has been in
several laptops and on a lot of Field Days. Not a cough in a
carload!  

To add to the advice by others on "grounding" the computer. What
we really mean is BONDING the chassis of the computer to the
chassis of the rig. For a laptop, the best place to find the
chassis may be the shell of the printer port (if there is one) or
shell of the video output.

The laptops I use for logging have a wire tied to a lug to that
port with a small screw, going to one Anderson Power Pole
connector. That mates to another one that goes to the rig. Makes
it easy to disconnect the laptop and use it somewhere else. Also
confuses the luggage inspectors at airports. :)

73,

Jim K9YC


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