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Greetings,
Been trying to track down a problem that has plagued me for months. I have
a large amount of RF coming into my shack via the coaxial shields and the
rotor cables--so much that it gets into the microphone audio of the rig.
I've driven new ground rods, used 1.5 inch braid to wire it, kept the braid
short, used ferrite, used caps, etc. 80 and 20 meters are the only effected
bands. 80 was so bad that it would blow the small meter fuse on my rotor
control box! I used .01 uf caps on all the leads into the rotor control box
to bleed it off with some success.
Both antennas have good baluns and the coax was tested at power by running
1KW up one line and down the other into a dummy load--no RFI problems. That
leads me to believe that it is inductively coupled onto the lines.
The question of the day--why?
I just ordered a couple of the T4G line isolators from Radioworks (basically
chokes with a ground strap on the braid)--I'm hoping I can get the RF off
the coax with them. How can I get it off the rotor control line before it
enters the house? I'm considering adding 40-50 ferrite beads to the control
line outside the shack (same location as the T4Gs) to choke off the RF and
adding a .01 uf cap from each line to ground on the "antenna-side" of the
"trap".
Any thoughts or ideas?
73 de Tom, K4NR
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<TITLE>RFI and the TS-850</TITLE>
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<BODY>
<P><FONT SIZE=3D2>Greetings,</FONT>
</P>
<P><FONT SIZE=3D2>Been trying to track down a problem that has plagued =
me for months. I have a large amount of RF coming into my shack =
via the coaxial shields and the rotor cables--so much that it gets into =
the microphone audio of the rig. I've driven new ground rods, used 1.5 =
inch braid to wire it, kept the braid short, used ferrite, used caps, =
etc. 80 and 20 meters are the only effected bands. 80 was =
so bad that it would blow the small meter fuse on my rotor control =
box! I used .01 uf caps on all the leads into the rotor control =
box to bleed it off with some success. </FONT></P>
<P><FONT SIZE=3D2>Both antennas have good baluns and the coax was =
tested at power by running 1KW up one line and down the other into a =
dummy load--no RFI problems. That leads me to believe that it is =
inductively coupled onto the lines.</FONT></P>
<P><FONT SIZE=3D2>The question of the day--why?</FONT>
</P>
<P><FONT SIZE=3D2>I just ordered a couple of the T4G line isolators =
from Radioworks (basically chokes with a ground strap on the =
braid)--I'm hoping I can get the RF off the coax with them. How =
can I get it off the rotor control line before it enters the =
house? I'm considering adding 40-50 ferrite beads to the control =
line outside the shack (same location as the T4Gs) to choke off the RF =
and adding a .01 uf cap from each line to ground on the =
"antenna-side" of the "trap".</FONT></P>
<P><FONT SIZE=3D2>Any thoughts or ideas?</FONT>
</P>
<P><FONT SIZE=3D2>73 de Tom, K4NR</FONT>
</P>
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