On Thu, 26 Oct 2006 14:06:53 GMT, "John, N9JG"
wrote:

When I operate on 75 meter SSB with my transceiver, my computer beeps and
disconnects/reconnects my USB connected keyboard. Note that I do not have
this problem on 40 meter SSB. My computer is located on the second floor of
a brick house, and one end of my dipole is about 15 feet from my shack.

From comments made by others, I may have to put RF filters on the cables
and wires connected to my computer. I am contemplating the use of
Amidon FT-240-77 ferrite toroids, which have an I.D. of 1.4 inches and
cost $9 each. If I buy in quantities of 10, is there a cheaper source
for this toroid?

Any comments or suggestions on this problem would be appreciated.


John,

You describe a problem that could be caused / exacerbated by one or
both of:
- lack of electromagnetic compatibility (EMC) of your computer; and
- a hostile RF environment.

Before you lay blame at the computer, it is worth whether the RF field
strengths, and conducted and induced currents and voltages in your
shack are unnecessarily high.

You have give very little description of your antenna, feedline, and
station earth... too scant to analyse and offer much advice.

The hint is there that this problem is evident on 80m, while 40m seems
OK. Why is that?

Is the identified PC problem really a manifestation of a "hot" shack?
Have you conducted any experiments to identify excessive common mode
feedline currents in the shack (the same procedures you might follow
if you got an RF burn from something in the shack)?

Owen

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