[TowerTalk] SHACK LOCATION VS GROUNDING & RFI

[W4ZW]

I agree with Jim.

It seems that I have nearly always wound up with an upper floor shack.  Here
I'm on the 3d floor, and in my last several QTH's, I've been on anything
from 2d (usually) to 14th and 18th (Europe).   Here I have an RF problem
because I have 3 yagis mounted on the roof top (4th floor), and high power
simply puts too much RF into the house wiring, alarm system, etc., so I am
limited to less than 400w on 40M and 80M.  For low power, there is no
problem at all since the antennas are all matched well, and the only
resident problems in the shack are the usual suspects (computer keyboard,
mouse, etc.)  A few ferrites take care of that easily.  And that has been
true for every other location I've had where I didn't have the transmitting
antennas just above the operating position.  Here, with the antennas so
close, high power is a different story.  I've loaded the alarm system,
stereos, TV lines, and just about every line with ferrites, and that
generally fixes the problem, except for the alarm system where I am sure
there are runs that are probably close to resonance on some bands and create
false alarms.  In contests, I simply disconnect the alarm system.  I
subscribe to the disconnect everything when not in use theory, and all feed
lines are disconnected from all equipment and grounded to the third floor
ground bus when not in use.  I've had lightening all around and have yet to
have a problem.  However, at my QTH in Orlando (lightening capitol of North
America) I had a rhombic that collected charges from any nearby thunderstorm
and I could see and hear the crackling in the coax.  Had to change coax
regularly along with the arrestor modules in the matching section which was
mounted at the base of the rhombic.  The performance wasn't worth the work
needed to keep it operational.

Summary:  Good,  resonant, matched antenna systems will minimize rf in the
shack.  Sometimes an artificial ground may be needed to provide a
counterpoise for a particularly persistent problem, but ferrites should cure
most problems.

YMMV,


Jon Hamlet, W4ZW

Casey Key Island, FL
"A little piece of paradise in the Gulf of Mexico"