[RTTY] Motherboard Recommendation

[Joe Subich, W4TV]

 > I don't know if the current continued through the interface to the
 > K3 or not.  I also don't know if the optoisolators in a RIGblaster
 > or a MicroHAM would have prevented that or not, but I'm wondering.

Most certainly not.  The voltages generally encountered in a lighting
event of this magnitude are far beyond the withstand capability of any
simple optoisolator.

Long, painful experience shows the only way to survive a lightning
event is proper attention to bonding:

   1) all cables must come off the tower at ground level (or in a
      metal encased "cable bridge" as in broadcast TV installations)
   2) all cables must be bonded to the tower at the top and bottom
      as well as periodically along the tower
   3) the tower grounding, the service entrance, telephone entrance,
      CATV entrance, and antenna feed line entrance must be at the
      same place or at least bonded with very low resistance and
      low inductance conductors

The key is to keep the lightning energy OUTSIDE of the ham shack
and to NEVER allow the voltage on signal returns, antenna feed
lines, power system safety ground and equipment chassis to differ.
By keeping the reference ("ground") levels on all signal lines
and equipment the same, it becomes impossible to create damaging
voltages within/across those devices.

73,

    ... Joe, W4TV

On 7/1/2010 8:08 AM, Jim McDonald wrote:
> I used to have a RIGblaster Plus and a Pro but used the simple/cheap
> transistor/resistor serial interface on AA5AU's web site for several years
> instead since it worked, was simple, and was cheap.
>
> In April, I suffered a big lightning strike to my antennas and tower, which
> also had a Motorola Canopy wireless internet unit on it.  The Canopy module
> was connected with CAT5 cable through an arrestor on my grounding panel and
> then to my wired router.  Being lazy, I didn't disconnect because I thought
> the storm wasn't very close.
>
> The Canopy unit and the router were destroyed, as were the motherboard NIC
> and a ByteRunner 4-port serial PCI board in the computer.  The lightning got
> into the shack via other control lines (rotator, remote antenna switch, and
> SteppIR) too, despite arrestors, and they were connected to the serial card.
>
> My K3 was damaged (now totally repaired and perfect), and yesterday I
> realized that the transistors in the RTTY/PTT interface were damaged too.  I
> don't know if the current continued through the interface to the K3 or not.
> I also don't know if the optoisolators in a RIGblaster or a MicroHAM would
> have prevented that or not, but I'm wondering.
>
> I repaired the computer with a new, 4-port SIIG serial card and an Ethernet
> card, but ended up using a new, very fast, Dell Studio XPS 8100 i7 PC with
> Windows 7/64 and 8M of RAM in the shack instead.  (My wife got the old
> Pentium 4 XP computer.)  I added a 2-port PCIe serial card in the new PC,
> which I will use for firmware updates to the K3, but I'm again thinking
> about a USB MKII instead of repairing the transistor/serial interface.
>
>
> Jim N7US
>
> -----Original Message-----
>
>
> ORIGINAL MESSAGE:
>
>>
>> Maybe it would be a good
>> time to ditch the serial port and get a "modern" USB interface like the
>> microHAM or West Mountain Radio units.
>
> REPLY:
>
> MicroHam, Rigblaster, etc. = $$$
>
> Homebrew serial cable = $
>
> I homebrewed my serial port cables in the mid-90s and have been using
> them ever since. Several Kenwoods, several Icoms, one Yaesu, countless
> computers, but always the same serial port cables. Full details and
> schematics in the MMTTY help files.
>
> And you don't need that little audio isolation transformer either. If
> you are getting hum, you have a ground differential of several
> millivolts AC between your radio and computer. Bond the two chassis
> together with a heavy strap and plug both of the AC power cords into
> the same outlet and the hum will go away.
>
> 73, Bill W6WRT
>
>
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