An even easier way to remove the static is with a 3M ohm resistor to ground.
http://www.ad5x.com/images/Articles/Static%20Bleed.pdf
Chris
KF7P
On Mar 27, 2014, at 1:11 PM, Patrick Greenlee wrote:
> Clay, my Hy-Gain Hy-Tower vertical antenna is mounted with no concrete and no
> radials on top of a 36x72 metal barn (NICE COUNTERPOISE). The base of the
> antenna is at about 25 ft above grade. At over 75 feet it is by far the
> tallest thing around and so is a target for collecting static electricity.
>
> Neons (depending on which you use) typically ionize and conduct at about 60
> volts depending on how bright the ambient light is shining on them. When
> they do conduct they make significant RF noise.
>
> I wrapped plenty of small copper wire around a scrap of PVC pipe. One layer
> of wire, adjacent windings no spacing and as neat as I could. I then
> inserted this RF choke into a larger scrap of PVC and waterproofed/sealed
> the ends with GE II silicone caulk (RTV) and then placed the choke across the
> ground and antenna feed at the location of the BALUN feeding the antenna.
>
> I looked up the necessary formulas for the size of the wire, number of
> turns/length, and diameter of the form to ensure I had more than enough X sub
> L at the low end of 160 meters. so that the RF choke would basically be seen
> as an open circuit to the RF on all 8 bands I use it on but of course be a
> short (or very low resistance) to static charges. The DC path to ground via
> the RF bleeds off static charges without the RF noise associated with gas
> discharge tubes such as neons etc.
>
> I have no illusions regarding the survivability of the DIY choke in the event
> of a direct hit but so far so good over a year into its life and it would be
> simple and cheap to replace it. I do not depend on it to handle a strike. I
> have store bought in-line coaxial lightning suppression devices. Since it
> drains charges down to the zero volt level I think it drains static charges
> that the tall (75 feet above grade to the top) gathers and reduces the
> likelihood of a direct hit.Should the antenna take a hit the choke will be
> toast and I'm out a dollar or so to replace it. Meanwhile, it is
> electrically quieter.
>
> I'm open for suggestions to improve my situation. Although the ham
> population in my zip-code has doubled in the last couple years (I took the
> other guy to the exam venue so he is a tad new to offer well seasoned advice)
> I still have to rely on books and the internet for getting ideas other than
> my own.
>
> Patrick NJ5G
>
>
> On 3/27/2014 10:02 AM, Clay Jackson wrote:
>> Very interesting discussion! Thought I'd share a little bit about my
>> shack - we're in Eastern Washington, in the middle of what used to be a 90
>> acre wheat field. I have a HyGain AV18HT (50' vertical) about 200' from
>> the house, and then a couple of VHF antennas on 30' masts bracketed to the
>> side of the house.
>>
>> When we had the house built, before the foundation was poured, I cadwelded a
>> #2 copper wire to one of the rebars in the middle of the foundation and left
>> it out. After the house was completed, I cadwelded that wire to an 8'
>> copper rod, then ran #2 wire around the 3 corners of the house, with an 8'
>> rod at each corner, all cadwelded - I also cadwelded that to the house AC
>> "Safety" ground, which is just another piece of rebar tied to the foundation
>> that comes up through the garage floor near the electrical panel.
>>
>> I have a DX Engineering Entry Panel, and my #2 copper wire terminates in
>> that panel, with the wire clamped to the aluminum plate inside the panel.
>> All of my antennas except the vertical enter through that panel, through
>> lightning arrestors bolted to the panel. The VHF antenna masts are mounted
>> in a pipe sleeve buried at least 4' into the ground, and there's an 8'
>> ground rod at each mast, cadwelded to the round-the-house ground wire.
>>
>> The HyGain Antenna is mounted on a 6x6x6 block of concrete - the "legs" were
>> clamped to the rebar in the concrete, and I left one of the pieces of rebar
>> above the concrete, to which I clamped the antenna ground and lightning
>> arrestor at the base. The AV18HT feeds the tower at the base (the legs sit
>> on insulators); and so I have a box with 8 neon bulbs in it connected
>> between the tower and ground as a static discharge.
>>
>> In the shack, I have a 6' strap of 2" wide copper braid, bolted to a 6'
>> long 2" copper pipe that sit on the back of my operating table. All of my
>> gear is connected to that pipe with 1/2" or bigger copper braid. The
>> operating table frame is constructed of 1x1 steel tubing, and that's also
>> connected to the ground pipe. All of my power comes through a generator
>> backed set of 3 UPS, 1 1500VA and 2 450VA.
>>
>> So far, I haven't had any DIRECT strikes; but, last year, we did get a
>> strike about 100' from the base of the tower that was pretty intense - no
>> damage to any of the rigs or other devices.
>>
>> Clay
>> N7QNM
>>
>> -----Original Message-----
>> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
>> Brown
>> Sent: Sunday, March 23, 2014 9:37 AM
>> To: towertalk@contesting.com
>> Subject: Re: [TowerTalk] Back of desk grounding buss
>>
>> That experience counts for lightning protection of commercial installations
>> with big budgets, setups that don't change, no local analog audio, and in a
>> broadcast environment, balanced audio. But that's not most ham stations. We
>> have limited budgets, we do everything ourselves, we change our setups as we
>> try new things, buy new gear, have lots of stuff interconnected, like
>> computers, rigs, amps, audio processors, SO2R boxes, and all of the
>> interconnections are UNbalanced.
>> Moreover, if it's FM broadcast, cellular, or VHF/UHF 2-way, most of those
>> antennas are high in the air and have nulls in the direction of the
>> equipment, whereas our antennas often produce significant field strength in
>> our shacks.
>>
>> Those interconnections, especially analog audio, is one big reason why
>> chassis-to-chassis bonding is far better than running individual wires to a
>> common point (or bus bar).
>>
>> And there is nothing about that chassis-to-chassis bonding that is less good
>> than individual wires to a common point. Remember that with those wires to a
>> common point, we still have a loop to create magnetic coupling -- it's
>> formed by the interconnections between the boxes and those long wires to the
>> common point.
>>
>> 73, Jim K9YC
>>
>> On 3/23/2014 8:44 AM, Jim Lux wrote:
>>> Your experience is probably more relevant. Especially with reference to
>> commercial practice.
>>> My thing is more about the theory behind the recommendations, which is
>>> often buried in the mists of history. Sort of like 468/f
>>>
>>> On Mar 23, 2014, at 3:53, n4zkf<towertalk@n4zkf.com> wrote:
>>>
>>>>> I didn't put a rover on mars but I do grounding on cell and
>>>>> broadcast sites for a living working in telecom. Does that count?
>>>>>
>> _______________________________________________
>>
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