[TenTec] Station Grounding

[Bob & Linda McGraw K4TAX]

Well, I kinda gotta dis-agree.  Seems that's what I do best lately.  I
don't have a station RF ground.

My station is on the 2nd floor of a 2 story wooden frame house. 
Actually it's in the middle of the house with no access to an outside
wall.  The feed lines (and rotor cable) go up to the crawl space,
carefully suspended from the roof rafters, out the eve and up the
tower.  If I put a ground on the station it would be 50 ft long to
earth.  As I figure it, this would be of no value at all.  I do use the
3rd pin AC for safety however.  Each piece of equipemnt is connected to
the Tentec power supply ground terminal via #10 stranded copper
jumpers.  Crimp terminals are used but then they are soldered in
addition after crimping.  I use some LCOF copper speaker wire as it's
nice and flexable.

The HF antennas are center fed wires: one fed with balanced feed for
160M (256 ft long) and a center fed wire for 75M (120 ft long).  The 75M
antenna is fed with RG-213 and I use a 5KW rated 1:1 current balun at
the antenna center feed point.  I use the 160M antenna on all bands as I
so desire and the 75M antenna on 75M and 10M.  The Tentec 238 tuner
keeps the rig happy.  No RF at any time here in the shack.....any band,
any mode, any frequency.

The rig is a Tentec Omni VI+, TT 705 desk mike, TT Centruion amp, TT 238
tuner.  NO TVI even thought the TV antenna is located on the side of the
Rohn 25G that supports the center of the wire antennas and the VHF 2M
array at the top.  (TV stations are 85 miles away so we are considered
to be in the fringe area of coverage.)  No telephone interference to the
wired or 900 MHz cordless phones here in the house (no mods done to the
phones either).  I operate 160M through 10M with these 2 antennas.  The
amp produces 1200+ watts output.  The computer monitor and keyboard is
on the same table as the ham station.  The computer tower sits on the
floor under the table.  No problem here either.  All of the station is
powered by a dedicated 30A 120V circuit that I ran direct from the
breaker panel to the operating position. (#10-3 w/g) The Centurion amp
has its own 240V 20A circuit. (#10-3 w/g)  With this arrangement I have
no ground loops thus I can use the computer and its soundcard to operate
PSK31 with no additional interface required.

I figure the secret is the fact that the antennas are balanced.  

As to tower/antenna grounding.  A single 8' copper clad driven ground
rod at a 45 degree angle to below ground level (4' down is solid rock
here at the QTH) is at the base of the tower.  A piece of 1/2" copper
soft copper water line, flattened on each end is bolted between the
tower leg and the ground rod.  Of note, the tower base elevation is 550
ft above average terain.  IMPORTANT: from this ground rod I have a #6
solid copper wire running to the AC driven ground on the other side of
the house some 60' away.  This wire follows the outside perimiter of the
house and is just under the soil.  Keep this in mind, all driven grounds
must be bonded together.  Failure to do this during a nearby lightening
strike will cause the IR drop across ground resistance to produce a
different potential in 2 ground points.  Your radio could be connected
between AC ground (point 1) and your radio ground/tower ground (point
2).  The resulting flow of current will most likely produce a radio that
fails to operate until repaired.  It may cause the smoke to be let out
of the box and we all know that when the smoke is let out of the box,
the box fails to function.

And finally, a whole house surge protector at a cost of $35 has been
installed across the 200A main breaker for the house.  The life of light
bulbs has doubled since this was done.  Plus all of the electronics,
TVs, VCRs, microwave, clocks and a host of other stuff benefits.

Sorry to be so long, but the effort is worth it.

73
Bob K4TAX



Ken & Linda Burrough wrote:
> 
> Hi All
> 
> Ken/W7TS
> 
> >>>I have installed three eight foot ground rods a couple feet apart right
> out
> side the shack.  I have installed a Number 2 copper wire from the ground
> rods to the antenna tuner ground screw.  I now intent to connect each of the
> pieces of equipment to the tuner ground screw with a separate copper strap.
> 
> Ken that should work with two changes.  If you can make the NR 2 copper wire
> bigger and install a longer grounding screw on the 238.  The grounding screw
> from Ten-Tec is short and intended for one grounding wire.  Also use an star
> washer and locking nut at the 238 and then an flat washer on top of the nut,
> then the grounding straps.  Last is an flat washer and nut, not a wing nut
> but a good nut that can be tightened.
> 
> Here is how my station ground is set up.  My Operating position/Computer
> station is ten foot long, I use a 10 foot piece of copper water pipe
> insulated from the wall.  Each piece of station or computer equipment that
> need grounded I use copper strap from the grounding lug to the copper
> grounding buss.  I use SS hose clamps to connect the grounding strap to the
> buss.  From the grounding buss I use large copper strap to the insulated
> wall feed through.  Outside the house I use double "O" stranded copper with
> a lug silver soldiered to one end.  This is attached to the wall feed
> through, the other end goes to my electric service ground rod.  I am using
> the power company grounding grid for my station ground.  I never have RF
> feed back in the shack.
> 
> Good luck.
> 
> Ken/w8keb
> Flushing, Ohio
> 
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