At 14:42 -0700 28/4/13, Roger (K8RI) wrote:
On 4/28/2013 11:21 AM, Timo Toro wrote:
I did fix my problems already. My antenna systems are not incomplete. Of
course more and higher masts would be nice, hi.
But if I run over 1KW to my 4el Yagi on 40m and my PC stops working, I
have to fix that problem. I did not use the band aid either. Nowadays my
ham shack is more like Faraday shield, hi. And lightning safe.
Sounds like what I had on 75 with a center fed half wave, sloping,
fan dipole. SWR at resonance is less than 1.1 : 1. When I'd get to
around a KW out, all the LEDs on the control heads in the station
would light. To me that said, RF on the feed line which meant it was
on the ground as well.
My first thought was a current balun.
http://www.rogerhalstead.com/ham_files/AntennaFeed1.htm
Not neat, but a very high impedance for common mod voltages. It
improved the situation but did not cure it, So I inserted another,
similar choke where the feed line reached the tower and no more RF
in the shack, feed lines, or ground.
I stopped the RF at the source.
Sounds fine. On my to do list there has been also to add common mode
chokes to the lines coming from mast. The more isolation between
computers inside the house and antennas the better.
I think all tin roofs should be grounded too. I have done it only to
my station building.
73, Timo_oh5kw
An antenna may appear to have all its parts, a good SWR, and a good
ground, but bear by objects, ground conditions under and near the
antenna may leave you with an unbalanced system even though every
thing looks good. Matter of fact, it's extremely unlikely that an
antenna will be truly balanced
73
Roger (K8RI)
I still like to use word "grounding" meaning low impedance route to
common point near earth potential.
73, Timo_oh5kw
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