It could be a number of things. First off, 8 foot ground
rods may give you some lightning protection, but they
aren't really much of an RF ground. Aside from the 3
ground rods on the tower, do you have any radials
attached? Also, are the shields of the coax cables running
from the shack to the base of the tower grounded to
You may be creating a big loop by connecting the
base of the tower to your other ground rod, if the tower
ground already connects to your shack ground via the
shields of your coax cables. The fact that you have
buzz in your sidetone suggests RF in the shack which
could be the result of a loop. Also, make sure all
the connections are tight and free from corrosion.
Anything that looks like a diode can act like a frequency
mulitiplier making for TVI problems. By the way,
have you determined if your TVI problems are due
to TV overload or stray RF on the AC line, or are you
generating harmonics of your trasmitted signal which
fall only on certain channels?
73 de Mike, W4EF.......................
----- Original Message -----
From: "FireBrick" <email@example.com>
To: "TowerTalk List" <firstname.lastname@example.org>
Sent: Wednesday, January 02, 2002 4:18 PM
Subject: [TowerTalk] tvi stopped when I removed a ground.
> I recently developed a SEVERE case of TVI to my home.
> It was total wipeout on 17, 20, 30, 40. Not so bad on 80 or 160.
> Very little on frequencies higher than 18 meters.
> Today was mild temps and I tried the following.
> I made a dramatic improvement in the above 17 meter tvi.
> Imagine this.
> I have two sets of 8 ft. ground rods. One rod is right outside the wall
> is connected
> to my 'on wall copper strip bus'.
> That's a thick piece of 2" wide copper that I mounted a number of brass
> bolts, washers, and thumb nuts on.
> All my equipment has short lengths of thick braid to the different bolts.
> One LARGE braid goes through the wall to a ground rod.
> The tower is approx 5 feet away and has it's own ground rods around three
> sides of the perimeter of the base. (forth side is adjacent to the
> foundation wall but has it's own ground rod going through the concrete to
> the earth below.) Well below the bottom of the concrete.
> I had a heavy strap connecting the one near the wall to the ring of rods
> around the tower.
> When I removed that strap, the tvi diminished to almost an imperceptible
> Also the harsh, raw sidetone note improved to a normal tone.
> Obviously there is a difference in potential in that 5 feet????
> Why would the tvi be worse when the tower and the shack systems were tied
> I thought that was a good thing?
> I wished the buck stopped here, as I could use a few.
> Bill H. in Chicagoland
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This list is sponsored by the new eHam.net Store. When you buy products
like ICE filters, Array Solutions StackMatch, or M-Squared Antennas from
the eHam Store for the same price you pay direct, a portion of the sale
price goes to support this list. Check it out at http://www.eham.net.
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Administrative requests: towertalk-REQUEST@contesting.com