[TowerTalk] SPG
vic watkins
vic.watkins at q.com
Wed Aug 4 22:06:35 PDT 2010
Tom, I feel your pain concerning the right vs wrong way to SPG.
However.....
To anyone who believes that the NEC can be ignored with impunity: your
insurance company may not be required to pay for any damages from any
type of induced current if your external antennas are not grounded per
the NEC. You may be able to fork over the cost for a new rig, but a new
house? Yes, this is worse case and the probability that your house will
burn down from induced currents is, well, you make that call on your own.
Yes, the cost of righteous SPG'ing can be high, but there is a
diminishing ROI and only you can make that call. It is somewhat similar
to how many radials to put down for a vertical; more is always better,
but when is enough enough? You make that call. SPG'ing can be somewhat
the same: 1) flat copper strap vs. 6, 4, 2 AWG wire; 2) bonding each
radio (and whatnot) to a separate ground rod vs. a common (in the) shack
ground bonded to a single ground rod that is SPG'ed; 3) SPG'ing each leg
of a tower to a ground run equivalent to the height of the tower with
ground rods every 10' vs. SPG'ing a single leg of the tower with a
single local ground rod; 4) running a ground ring completely around the
house vs. shortest ground path directly to the power main; 5); 6); 7)....
Each has to do what each can do, as is the case in all endeavors.
However, if you choose to not to follow the NEC, the insurance company
may choose not to pay. Calculate your risk acceptance level and your
economic situation and do what comes next.
73,
Vic, W7VLW
On 8/4/2010 10:50 AM, Tom Martin wrote:
> Don says,
> "The common practice, many years ago, was the 'daisy-chain' the ground
> from box to box to box, etc ... and then ONE wire went to ground.
> This is a problem waiting to happen.
>
> Tie EACH of the 'boxes' in the shack to the SPG outside with SEPARATE
> ground wires. Thus, the SPG you have serves its purpose. "
>
> In a typical SO2R station, that would be 17-20 different wires going to the
> ground rod. I would like to know how many on this reflector have that
> amount? Half that amount?
>
> This SPG discussion is giving me a headache! HI!
>
> For some , the cost of an ideal ground system is more than the equipment is
> worth. As long as my $4,000 Alpha amp is safe, I'll take my chances with
> the MP and Pro II. Insurance premiums and deductibles are less expensive,
> for the most part.
>
> 73,
>
> Tom W8JWN
>
> ----- Original Message -----
> From:<towertalk-request at contesting.com>
> To:<towertalk at contesting.com>
> Sent: Wednesday, August 04, 2010 11:21 AM
> Subject: TowerTalk Digest, Vol 92, Issue 15
>
>
>
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>>
>> Today's Topics:
>>
>> 1. Need sources of rope and fiberglass (Charles Harpole)
>> 2. Re: FOLLOWUP ON MY GROUND PROB; LEMS IN HOUSE AND SHACK
>> (Jim Brown)
>> 3. Re: Need sources of rope and fiberglass (Mark Robinson)
>> 4. Re: Fwd: shack wiring (Don Tucker)
>> 5. Re: Need sources of rope and fiberglass (W5CPT Clint)
>> 6. A different question (I think) on SPG (Gary E. Jones)
>> 7. Re: A different question (I think) on SPG (n8de at thepoint.net)
>> 8. Re: A different question (I think) on SPG (Kipton Moravec)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Wed, 4 Aug 2010 14:38:28 +0000
>> From: Charles Harpole<k4vud at hotmail.com>
>> Subject: [TowerTalk] Need sources of rope and fiberglass
>> To:<towertalk at contesting.com>, Florida ContestGroup<fcg at kkn.net>,
>> <cubex at cubex.com>
>> Message-ID:<COL107-W59ED503B96BC66E82AA69BF7AF0 at phx.gbl>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>>
>> Hope someone can refer me to a source for
>>
>> ---very light weight, very strong (500 lbs. pull), non absorbent, sun
>> resistant line/string/rope to use to internally guy a two element quad.
>>
>> -- light weight 8 foot fiberglass rod or tube, at least 1 and half inch
>> diameter.
>>
>>
>> Well, my quad broke today in a gale. The wind estimater says speed was 50
>> to 56 mph based on small tree blown over, twigs and limbs down, and so on.
>> I am impressed that the grass in the lots beside and behind me ... grass
>> about 2 ft tall, was blown completely flat, so he wind at actual ground
>> level was bad, too. Standard factory Cubex with factory stiffner... 2 el
>> full size 40m, 2el on 30, and 3 el on other two WARC bands. Really worked
>> nice!
>>
>> I made the mistake of not heading my quad West where the wind always comes
>> from... I think because it hit it on an angle, one of the top two
>> spreaders broke at about the half way point and all the wires of the
>> driven element are drooping over the mess that is left. The reflector,
>> lacking he added load of the driven coax attached, survived. I think the
>> driven array also rotated on the boom and the whole thing could have been
>> pushed back on the mast, it appears.
>>
>> I had plans already of putting in 8ft extensions on the ends of the boom
>> and tying the whole thing into a fully guyed internally. I do not know
>> how I can get another fiberglass spreader shipped here, it is very long,
>> and I have only one fiberglass extension rod to do the strengthening so
>> that is another part to find.
>>
>> If you have suggestions on a very light very strong, sun resistant, non
>> absorbing string, line, rope.... please let me know. de HS0ZCW
>>
>> Charly
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Wed, 04 Aug 2010 08:36:59 -0700
>> From: "Jim Brown"<jim at audiosystemsgroup.com>
>> Subject: Re: [TowerTalk] FOLLOWUP ON MY GROUND PROB; LEMS IN HOUSE
>> AND SHACK
>> To: "TowerTalk at contesting.com"<TowerTalk at contesting.com>
>> Message-ID:<20100804153700.692BB58F55 at gw1.nlenet.net>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> On Wed, 04 Aug 2010 02:46:00 -0500, Fred wrote:
>>
>>
>>> Here is how I ended up doing it all in tyhe end now.
>>>
>> I don't see where you have bonded the new ground rods to the other ground
>> rods. This is CRITICAL for lightning safety, and it is required by all
>> electrical codes, including the National Elecrical Code.
>>
>> Repeat after me, and write 100 times on the blackboard.
>>
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>> You can have as many grounds as you like, but they MUST be bonded
>> together.
>>
>> 73, Jim K9YC
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Wed, 4 Aug 2010 11:39:08 -0400
>> From: "Mark Robinson"<markrob at mindspring.com>
>> Subject: Re: [TowerTalk] Need sources of rope and fiberglass
>> To: "Charles Harpole"<k4vud at hotmail.com>,<towertalk at contesting.com>,
>> "Florida ContestGroup"<fcg at kkn.net>,<cubex at cubex.com>
>> Message-ID:<00b001cb33eb$2e8b3fc0$6600a8c0 at hplaptop>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> reply-type=original
>>
>> Take a look at this
>>
>> http://www.synthetictextilesinc.com/supportham.html
>>
>>
>>
>> Mark N1UK
>>
>>
>> ----- Original Message -----
>> From: "Charles Harpole"<k4vud at hotmail.com>
>> To:<towertalk at contesting.com>; "Florida ContestGroup"<fcg at kkn.net>;
>> <cubex at cubex.com>
>> Sent: Wednesday, 04 August, 2010 10:38 AM
>> Subject: [TowerTalk] Need sources of rope and fiberglass
>>
>>
>>
>>> Hope someone can refer me to a source for
>>>
>>> ---very light weight, very strong (500 lbs. pull), non absorbent, sun
>>> resistant line/string/rope to use to internally guy a two element quad.
>>>
>>> -- light weight 8 foot fiberglass rod or tube, at least 1 and half inch
>>> diameter.
>>>
>>>
>>> Well, my quad broke today in a gale. The wind estimater says speed was
>>> 50
>>> to 56 mph based on small tree blown over, twigs and limbs down, and so
>>> on.
>>> I am impressed that the grass in the lots beside and behind me ... grass
>>> about 2 ft tall, was blown completely flat, so he wind at actual ground
>>> level was bad, too. Standard factory Cubex with factory stiffner... 2 el
>>> full size 40m, 2el on 30, and 3 el on other two WARC bands. Really
>>> worked
>>> nice!
>>>
>>> I made the mistake of not heading my quad West where the wind always
>>> comes
>>> from... I think because it hit it on an angle, one of the top two
>>> spreaders broke at about the half way point and all the wires of the
>>> driven element are drooping over the mess that is left. The reflector,
>>> lacking he added load of the driven coax attached, survived. I think the
>>> driven array also rotated on the boom and the whole thing could have been
>>> pushed back on the mast, it appears.
>>>
>>> I had plans already of putting in 8ft extensions on the ends of the boom
>>> and tying the whole thing into a fully guyed internally. I do not know
>>> how I can get another fiberglass spreader shipped here, it is very long,
>>> and I have only one fiberglass extension rod to do the strengthening so
>>> that is another part to find.
>>>
>>> If you have suggestions on a very light very strong, sun resistant, non
>>> absorbing string, line, rope.... please let me know. de HS0ZCW
>>>
>>> Charly
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Wed, 4 Aug 2010 08:44:36 -0700
>> From: "Don Tucker"<w7wll at arrl.net>
>> Subject: Re: [TowerTalk] Fwd: shack wiring
>> To:<towertalk at contesting.com>
>> Message-ID:<772E6A8FFFCD4D13A966D2D0EDA04061 at n4j8v5>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Just what should the wire size be from the pole xmfr to the house and into
>> the 200A panel?
>>
>> Don W7WLL
>>
>> ## ha ha. I had the power co guy's out here a few months back..and asked
>> them
>> the same thing. Their answer was... "go ahead and burn it right off the
>> pole" .
>> Here in NA, we are being sold a bill of goods. Everyone has '200 A'
>> service...
>> but the drop wire into each home is just 1-0 stranded AL.... which then
>> gets
>> spliced into 3-000 stranded CU. .. then into the meter base [which is the
>> most
>> mickey mouse, piss poor design you ever saw, regardless of who makes em]
>> ..
>> then into main 200A panel.. which imo, they all use undersize buss bars.
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Wed, 4 Aug 2010 10:45:21 -0500
>> From: "W5CPT Clint"<w5cpt at bellsouth.net>
>> Subject: Re: [TowerTalk] Need sources of rope and fiberglass
>> To:<towertalk at contesting.com>
>> Message-ID:<CF9746649F7A4695B7D304F5027E0E55 at ownerPC>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> reply-type=original
>>
>> I don't know about the fiberglass but I would use Phillystran HPTG1200I
>> for
>> the the Quad stays. A bit pricey at $0.49 @ foot and $4 per end, but you
>> only have to buy it once. I had an antenna that would either stretch or
>> break the boom support rope in the slightest wind (lots of sun
>> degradation -
>> Texas). Replaced with the Phillystran and never worried about it again.
>> No
>> stretch, no breakage& no worries.
>>
>> Clint - W5CPT - West Kentucky
>>
>>
>> --------------------------------------------------
>> From: "Charles Harpole"<k4vud at hotmail.com>
>> Sent: Wednesday, August 04, 2010 9:38 AM
>> To:<towertalk at contesting.com>; "Florida ContestGroup"<fcg at kkn.net>;
>> <cubex at cubex.com>
>> Subject: [TowerTalk] Need sources of rope and fiberglass
>>
>>
>>> Hope someone can refer me to a source for
>>>
>>> ---very light weight, very strong (500 lbs. pull), non absorbent, sun
>>> resistant line/string/rope to use to internally guy a two element quad.
>>>
>>> -- light weight 8 foot fiberglass rod or tube, at least 1 and half inch
>>> diameter.
>>>
>>>
>>> Well, my quad broke today in a gale. The wind estimater says speed was
>>> 50
>>> to 56 mph based on small tree blown over, twigs and limbs down, and so
>>> on.
>>> I am impressed that the grass in the lots beside and behind me ... grass
>>> about 2 ft tall, was blown completely flat, so he wind at actual ground
>>> level was bad, too. Standard factory Cubex with factory stiffner... 2 el
>>> full size 40m, 2el on 30, and 3 el on other two WARC bands. Really
>>> worked
>>> nice!
>>>
>>> I made the mistake of not heading my quad West where the wind always
>>> comes
>>> from... I think because it hit it on an angle, one of the top two
>>> spreaders broke at about the half way point and all the wires of the
>>> driven element are drooping over the mess that is left. The reflector,
>>> lacking he added load of the driven coax attached, survived. I think the
>>> driven array also rotated on the boom and the whole thing could have been
>>> pushed back on the mast, it appears.
>>>
>>> I had plans already of putting in 8ft extensions on the ends of the boom
>>> and tying the whole thing into a fully guyed internally. I do not know
>>> how I can get another fiberglass spreader shipped here, it is very long,
>>> and I have only one fiberglass extension rod to do the strengthening so
>>> that is another part to find.
>>>
>>> If you have suggestions on a very light very strong, sun resistant, non
>>> absorbing string, line, rope.... please let me know. de HS0ZCW
>>>
>>> Charly
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>> ------------------------------
>>
>> Message: 6
>> Date: Wed, 4 Aug 2010 10:51:37 -0500
>> From: "Gary E. Jones"<garyejones at cmaaccess.com>
>> Subject: [TowerTalk] A different question (I think) on SPG
>> To:<towertalk at contesting.com>
>> Message-ID:<023901cb33ec$ecacff10$c606fd30$@com>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> I have read the threads on SPG over the years, but I think I don't really
>> understand a couple of concepts that are fundamental. Maybe someone can
>> help.
>>
>>
>>
>> I live in a 4000 square foot ranch house which is in the shape of a "U"
>> with
>> sleeping areas on one end of one leg of the U, and Garage/laundry/den on
>> the
>> other leg of the U, and the traditional living areas in the center of the
>> U.
>> The house has two 200A 240 volt distribution panels as the house was all
>> electric initially. The phone and power services all come into the house
>> on
>> the garage end of one leg of the U. The shack is one of the bedrooms on
>> the
>> other leg of the U.
>>
>>
>>
>> Further, the house is 500' from the two 90' crank up towers, each with two
>> yagis stacked on them. The towers are grounded through three ground rods
>> per
>> tower. Further, the feedlines for the yagis (buryflex) enter into
>> weatherproof boxes mounted on 4x4 weather resistant posts. The boxes have
>> remote coax switches in them to switch the various yagis on each tower.
>> The
>> remote switches are grounded and I will be separately grounding each piece
>> of buryflex at the base of the towers. There is Heliax from the remote
>> switches (500' for one tower and 600' for the other tower) to the house.
>>
>>
>>
>> Now, I assume there is no logic of trying to put the house and the two
>> towers at the same common ground point and that the towers have to be
>> separately grounded at their base (the way that I have it now). That means
>> there is a 500 and 600 foot separation between the towers and the house.
>> Further, the shack is on one side of the house and the common utility
>> grounds are in the center of the house. I have a separate ground rod right
>> outside the shack window, so it is not a SPG even for the house.
>>
>>
>>
>> Now, is the conventional wisdom that I have a problem?
>>
>>
>>
>> I can't see an easy or even possible solution. It seems to me that the
>> towers have to be grounded separately, and short of running a ground strap
>> a
>> hundred feet and boring either under my slab or around my swimming pool,
>> there is no easy way to even have a SPG for the house.
>>
>>
>>
>> One more thing, it has always seemed to me that at the exact instant that
>> a
>> tower or antenna gets hit with lightening, the tower ground is going to be
>> many volts higher than a second ground 500' away as the charge dissipates
>> into the tower "ground". That is going to put a very large voltage
>> difference between the two and is my understanding of the whole logic of
>> SPG. Am I correct or wrong in my assumptions? However, if they are all
>> tied
>> together, for that same fraction of a second, isn't everything "hot" (even
>> the "ground") relative to any other ground that is separated from the
>> common
>> ground?
>>
>>
>>
>> Straighten out my thinking.
>>
>>
>>
>> Thanks in advance
>>
>>
>>
>> 73
>>
>>
>>
>> Gary W5FI
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 7
>> Date: Wed, 04 Aug 2010 12:19:12 -0400
>> From: n8de at thepoint.net
>> Subject: Re: [TowerTalk] A different question (I think) on SPG
>> To: "Gary E. Jones"<garyejones at cmaaccess.com>
>> Cc: towertalk at contesting.com
>> Message-ID:<20100804121912.9qlurf8woc40osk4 at webmail.win.net>
>> Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
>> format="flowed"
>>
>> Gary,
>>
>> Your thinking isn't 'crooked', so it doesn't need straightening.
>>
>> You are confused by the term SPG. It does NOT mean that EVERYTHING is
>> tied to ONE POINT!
>>
>> The ground you have outside your shack is the SPG for your
>> equipment/shack, provided all 'boxes' in the shack are tied to it and
>> not simply to each other.
>>
>> The common practice, many years ago, was the 'daisy-chain' the ground
>> from box to box to box, etc ... and then ONE wire went to ground.
>> This is a problem waiting to happen.
>>
>> Tie EACH of the 'boxes' in the shack to the SPG outside with SEPARATE
>> ground wires. Thus, the SPG you have serves its purpose.
>>
>> The grounds at each tower are great for dissipating the initial 'blow'
>> if struck, but NOTHING will keep the 'strike current' from travelling
>> from tower to shack.
>>
>> The idea is to MINIMIZE the potential damage.
>>
>> Good luck
>> 73
>> Don
>> N8DE
>>
>>
>> Quoting "Gary E. Jones"<garyejones at cmaaccess.com>:
>>
>>
>>> I have read the threads on SPG over the years, but I think I don't really
>>> understand a couple of concepts that are fundamental. Maybe someone can
>>> help.
>>>
>>>
>>>
>>> I live in a 4000 square foot ranch house which is in the shape of a "U"
>>> with
>>> sleeping areas on one end of one leg of the U, and Garage/laundry/den on
>>> the
>>> other leg of the U, and the traditional living areas in the center of the
>>> U.
>>> The house has two 200A 240 volt distribution panels as the house was all
>>> electric initially. The phone and power services all come into the house
>>> on
>>> the garage end of one leg of the U. The shack is one of the bedrooms on
>>> the
>>> other leg of the U.
>>>
>>>
>>>
>>> Further, the house is 500' from the two 90' crank up towers, each with
>>> two
>>> yagis stacked on them. The towers are grounded through three ground rods
>>> per
>>> tower. Further, the feedlines for the yagis (buryflex) enter into
>>> weatherproof boxes mounted on 4x4 weather resistant posts. The boxes have
>>> remote coax switches in them to switch the various yagis on each tower.
>>> The
>>> remote switches are grounded and I will be separately grounding each
>>> piece
>>> of buryflex at the base of the towers. There is Heliax from the remote
>>> switches (500' for one tower and 600' for the other tower) to the house.
>>>
>>>
>>>
>>> Now, I assume there is no logic of trying to put the house and the two
>>> towers at the same common ground point and that the towers have to be
>>> separately grounded at their base (the way that I have it now). That
>>> means
>>> there is a 500 and 600 foot separation between the towers and the house.
>>> Further, the shack is on one side of the house and the common utility
>>> grounds are in the center of the house. I have a separate ground rod
>>> right
>>> outside the shack window, so it is not a SPG even for the house.
>>>
>>>
>>>
>>> Now, is the conventional wisdom that I have a problem?
>>>
>>>
>>>
>>> I can't see an easy or even possible solution. It seems to me that the
>>> towers have to be grounded separately, and short of running a ground
>>> strap a
>>> hundred feet and boring either under my slab or around my swimming pool,
>>> there is no easy way to even have a SPG for the house.
>>>
>>>
>>>
>>> One more thing, it has always seemed to me that at the exact instant that
>>> a
>>> tower or antenna gets hit with lightening, the tower ground is going to
>>> be
>>> many volts higher than a second ground 500' away as the charge dissipates
>>> into the tower "ground". That is going to put a very large voltage
>>> difference between the two and is my understanding of the whole logic of
>>> SPG. Am I correct or wrong in my assumptions? However, if they are all
>>> tied
>>> together, for that same fraction of a second, isn't everything "hot"
>>> (even
>>> the "ground") relative to any other ground that is separated from the
>>> common
>>> ground?
>>>
>>>
>>>
>>> Straighten out my thinking.
>>>
>>>
>>>
>>> Thanks in advance
>>>
>>>
>>>
>>> 73
>>>
>>>
>>>
>>> Gary W5FI
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 8
>> Date: Wed, 04 Aug 2010 11:21:03 -0500
>> From: Kipton Moravec<kip at kdream.com>
>> Subject: Re: [TowerTalk] A different question (I think) on SPG
>> To: "Gary E. Jones"<garyejones at cmaaccess.com>
>> Cc: towertalk at contesting.com
>> Message-ID:<1280938863.11389.56.camel at red>
>> Content-Type: text/plain
>>
>> Let me see if I can take a whack at this.
>>
>> On Wed, 2010-08-04 at 10:51 -0500, Gary E. Jones wrote:
>>
>>> I have read the threads on SPG over the years, but I think I don't really
>>> understand a couple of concepts that are fundamental. Maybe someone can
>>> help.
>>>
>>>
>>>
>>> I live in a 4000 square foot ranch house which is in the shape of a "U"
>>> with
>>> sleeping areas on one end of one leg of the U, and Garage/laundry/den on
>>> the
>>> other leg of the U, and the traditional living areas in the center of the
>>> U.
>>> The house has two 200A 240 volt distribution panels as the house was all
>>> electric initially. The phone and power services all come into the house
>>> on
>>> the garage end of one leg of the U. The shack is one of the bedrooms on
>>> the
>>> other leg of the U.
>>>
>>>
>> Make sure phone and power grounds are tied together.
>>
>>
>>>
>>> Further, the house is 500' from the two 90' crank up towers, each with
>>> two
>>> yagis stacked on them. The towers are grounded through three ground rods
>>> per
>>> tower. Further, the feedlines for the yagis (buryflex) enter into
>>> weatherproof boxes mounted on 4x4 weather resistant posts. The boxes have
>>> remote coax switches in them to switch the various yagis on each tower.
>>> The
>>> remote switches are grounded and I will be separately grounding each
>>> piece
>>> of buryflex at the base of the towers. There is Heliax from the remote
>>> switches (500' for one tower and 600' for the other tower) to the house.
>>>
>> When you get a lightning strike where do you want the power to go? Down
>> your switch wires and coax or down a ground wire? (Ground Wire is the
>> correct answer.)
>>
>>>
>>>
>>> Now, I assume there is no logic of trying to put the house and the two
>>> towers at the same common ground point and that the towers have to be
>>> separately grounded at their base (the way that I have it now). That
>>> means
>>> there is a 500 and 600 foot separation between the towers and the house.
>>> Further, the shack is on one side of the house and the common utility
>>> grounds are in the center of the house. I have a separate ground rod
>>> right
>>> outside the shack window, so it is not a SPG even for the house.
>>>
>>>
>> O.K. where is the lightning going to go to find the lowest point ground?
>> > From the tower to the coax. Some will be dumped at ground rod at the
>> shack window. The rest will try to get to the ground at the house power
>> service panel. Unfortunately your transceiver is in that path.
>>
>>>
>>
>>> Now, is the conventional wisdom that I have a problem?
>>>
>>>
>> You have a problem.
>>
>>
>>>
>>> I can't see an easy or even possible solution. It seems to me that the
>>> towers have to be grounded separately, and short of running a ground
>>> strap a
>>> hundred feet and boring either under my slab or around my swimming pool,
>>> there is no easy way to even have a SPG for the house.
>>>
>>>
>> It sounds like that may be what you have to do. You have to tie all the
>> grounds together. You want the house ground to move with the antenna
>> ground and your entrance ground, so the power from the lightning goes
>> through that ground wire and not through the house wires taking
>> everything out with it.
>>
>>
>>>
>>> One more thing, it has always seemed to me that at the exact instant that
>>> a
>>> tower or antenna gets hit with lightening, the tower ground is going to
>>> be
>>> many volts higher than a second ground 500' away as the charge dissipates
>>> into the tower "ground". That is going to put a very large voltage
>>> difference between the two and is my understanding of the whole logic of
>>> SPG. Am I correct or wrong in my assumptions? However, if they are all
>>> tied
>>> together, for that same fraction of a second, isn't everything "hot"
>>> (even
>>> the "ground") relative to any other ground that is separated from the
>>> common
>>> ground?
>>>
>> Precisely. That is the idea of what you are trying to do. As all grounds
>> go up to a higher potential together, there is no potential across your
>> equipment, and your equipment does not smoke.
>>
>> Think of a bird sitting on a power line. Even though there are hundreds
>> of volts in the line the bird does not die, because the the power does
>> not go through him, it is easier for the power to go through the wire he
>> is sitting on.
>>
>>>
>>>
>>> Straighten out my thinking.
>>>
>>>
>>>
>>> Thanks in advance
>>>
>>>
>>>
>>> 73
>>>
>>>
>>>
>>> Gary W5FI
>>>
>>>
>>>
>> --
>> Kipton Moravec AE5IB .- . ..... .. -...
>>
>> "Always do right; this will gratify some people and astonish the rest."
>> --Mark Twain
>>
>>
>>
>>
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>>
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>>
>>
>> End of TowerTalk Digest, Vol 92, Issue 15
>> *****************************************
>>
>
>
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