Sometimes you can teach an old horse the correct way to do things.
In anticipation of possibly running high power this weekend, I have been trying
to cure an RFI problem on a CAT5 cable run to the next room for network
connection to my girlfriend Shay's PC. I had a CAT5 cable run over there with
two ferrite toroids on both ends of the cable. But despite the torroids, the
network would showed disconnected when I transmitted a KW on 15 meter RTTY.
The run is less than 9 feet. I know that because I tried using a 3 meter fiber
optic cable to a couple of 10-base T fiber transceivers tonight but couldn't get
that to work. I may have needed 100-base T transceivers. But they were free so
thought I would try.
After failing at that, I remembered something a colleague told me earlier today
when discussing this problem. He asked if I was using the standard CAT5 wiring
scheme. He said the standard CAT5 wiring scheme was suppose to help eliminate
electromagnetic interference such as RF. I told him yes because I thought I
was, but after looking on the Internet I discovered I was not using the standard
wiring scheme:
White-Green
Green
White-Orange
Blue
White-Blue
Orange
While-Brown
Brown
So I decided to run a new cable. Before putting the connectors on each end, I
wound 8 turns around a small #77 ferrite toroid on each end (remember I had two
of these toroids on each end previously). I then put the RJ45 connectors on
using the above wiring scheme.
Guess what? It worked. No more RFI into the cable. No more disconnecting from
the network. Tested on all bands on 80 meters.
Shay will be quite happy to surf the Net while I'll pumping a KW out on 15
meters this weekend if I decide to go high power.
I also received the ICE TVI filters but it didn't completely fix the new flat
screen TV in the bedroom despite the cable being wound on a big #77 ferrite
torroid at the input of the filter. The picture doesn't completely blank out
but it does change shades when running a KW on 40 meters (no big deal really).
500 watts is OK. No other TV's in the house are affected (without using any
filter or toroids).
I will install a filter on the neighbor's TV before the contest. They have only
one TV and do not have cable. They are using a rabbit ears antenna sitting on
top of the TV. They don't watch much TV apparently but do want to fix them up.
Now if I could keep the living room phone from ringing while operating high
power on 80 meters, I'll be in business!!! hi (that one's easy - unplug the
phone at night while on 80M).
I'm still not sure if I will run high power but I'm strong leaning toward it
especially now that I'm having some success with RFI. It's been a learning
experience, but everything is, isn't it?
Unfortunately Ivan has returned in the form of Tropical Storm Ivan just south of
New Orleans in the Gulf of Mexico. A low pressure remnant of Ivan circled all
the way around, came over Florida and reformed in the Gulf. After some debate,
the National Hurricane Center decided to name it Ivan again. Heartless
bastards!
Hopefully it will go into Texas and disappear forever, but it's bringing rain to
us now and I sure don't need rain this weekend.
73 & see everyone this weekend, high or low power.
Don AA5AU
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