harnessing lightning, or not
in [Design]
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From: Joerg on 14 Jun 2010 10:39 Paul Keinanen wrote: > On Sun, 13 Jun 2010 17:57:47 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Michael A. Terrell wrote: >>> Joerg wrote: >>>> Michael A. Terrell wrote: >>>>> Joerg wrote: >>>>>> John Larkin wrote: >>>>>>> On 12 Jun 2010 07:16:54 -0700, Winfield Hill >>>>>>> <Winfield_member(a)newsguy.com> wrote: >>>>>>> >>>>>>>> My Maxwell capacitors hard at work energy from harnessing lightning, see my post >>>>>>>> with photo, at the CR4 forum. >>>>>>>> >>>>>>>> http://cr4.globalspec.com/thread/55751/Lightning-Arrestor#comment579837 >>>>>>> You rate 3 "good" answers out of 14. That site has very high >>>>>>> standards! >>>>>>> >>>>>>> Why not use the lightning to heat water? The impedance match is >>>>>>> potentially better, and it's easy to store hot water. We could throw a >>>>>>> neighborhood hot-tub party after every strike, every 40 years or so. >>>>>>> >>>>>>> We don't get lightning here. I kind of miss it. >>>>>>> >>>>>> I don't miss it, seen to much electronics come to grief from it. Hey, >>>>>> why don't engineers at RF module manufacturers get it into their heads >>>>>> that the first part after the antenna jack has got to be an inductor to >>>>>> ground? Anything else will eventually go *PHUT*. > > Some filtering would be required to keep out strong out of band > signals (such as broadcasting radio and TV or radar) from overloading > the front end. The inductor to ground would come naturally as part of > a parallel LC filter. > Most of this stuff is nowadays wideband so you'll find low/highpass combos. Or sometimes nothing. Lightning typically has most of its spectral energy under 1MHz. Easy to muffle but many if not most designers of RF module fail to do so. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 14 Jun 2010 10:43 Michael A. Terrell wrote: > Joerg wrote: >> Michael A. Terrell wrote: >>> Joerg wrote: >>>> Michael A. Terrell wrote: >>>>> Joerg wrote: >>>>>> John Larkin wrote: >>>>>>> On 12 Jun 2010 07:16:54 -0700, Winfield Hill >>>>>>> <Winfield_member(a)newsguy.com> wrote: >>>>>>> >>>>>>>> My Maxwell capacitors hard at work energy from harnessing lightning, see my post >>>>>>>> with photo, at the CR4 forum. >>>>>>>> >>>>>>>> http://cr4.globalspec.com/thread/55751/Lightning-Arrestor#comment579837 >>>>>>> You rate 3 "good" answers out of 14. That site has very high >>>>>>> standards! >>>>>>> >>>>>>> Why not use the lightning to heat water? The impedance match is >>>>>>> potentially better, and it's easy to store hot water. We could throw a >>>>>>> neighborhood hot-tub party after every strike, every 40 years or so. >>>>>>> >>>>>>> We don't get lightning here. I kind of miss it. >>>>>>> >>>>>> I don't miss it, seen to much electronics come to grief from it. Hey, >>>>>> why don't engineers at RF module manufacturers get it into their heads >>>>>> that the first part after the antenna jack has got to be an inductor to >>>>>> ground? Anything else will eventually go *PHUT*. >>>>> Yawn. >>>>> >>>> T'is what I did when I just encountered the umpteenth module where that >>>> was done wrong :-) >>> >>> Yawn, as in: WHAT ABOUT ALL THE RF EQUIPMENT WITH A DC VOLTAGE AT THE >>> INPUT CONNECTOR? >>> >> Gear out in the field typically never has that. I've done a lot of RF >> designs and even more re-designs by now. The number of units that would >> be DC-fed or have to provide LNA power was zero. Fact is, units deployed >> in the south or on the island won't even live through the first year >> with a nice big inductor to ground. Lightning strike into some fence out >> there, voltage surge, somewhere above 100V the input cap decides it's >> had it ... *POP* ... preamp and final TX amp are goners. >> >> Of course, if you design sat-gear that's different. > > > If they won't survive, why are there hundreds of Dish and Direct > satellite companies around here? Or line powered TV preamps? The only > RF equipment I've lost was due to a direct strike that scatter pieces of > the amplified TV antenna over about 1000 square feet. This is the > highest lightning strike are in the US. > Because the LNAs protect them by dying in their place :-) > I've had a 5 meter sat dish hit by lightning. I lost all of the LNAs, > but not one sat receiver. The biggest risk is poorly grounded systems. > Its amazing to see MATV or other head ends and equipment rooms with a > piece of 14 gauge wire looped around the room and connected to an > outlet. Then they think they are protected. You need a good, heavy > duty rack and a good grounding system. One head end ended up with a > ground rod for each rack, and bare 8 AWG solid copper wire. All of > antenna lines were rerouted to a 1/4" aluminum ground plane. It was > tied to the new grounding system. From what I heard, they never had > problems from lightning again, even though the tower has been struck > several times. > > When I was repairing CATV headend equipment it was amazing how poorly > designed some equipment was. The best had a rf transformer at the input > for isolation. Some didn't even have a resistor across the input > connector to bleed off a static charge. The typical value was around > 4.7K. > See? That's the stuff I also find and I bet your experience is more than a decade ago. That would mean in a decade or more almost nothing has been learned about lightning effects. What really irks me is that they still don't seem to teach this sort of practical stuff at universities. > Another problem was thin steel chassis, held together by sheet metal > screws. The spot welded aluminum cases were better, and used PEM nuts > to secure the cover. The heavy case had a lot lower impedance to ground > than the cheap steel cases. > I usually have to deal with <gasp> PVC or ABS :-( -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Spehro Pefhany on 14 Jun 2010 13:56 On Mon, 14 Jun 2010 03:04:03 -0400, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > >Joerg wrote: >> >> Michael A. Terrell wrote: >> > Joerg wrote: >> >> Michael A. Terrell wrote: >> >>> Joerg wrote: >> >>>> John Larkin wrote: >> >>>>> On 12 Jun 2010 07:16:54 -0700, Winfield Hill >> >>>>> <Winfield_member(a)newsguy.com> wrote: >> >>>>> >> >>>>>> My Maxwell capacitors hard at work energy from harnessing lightning, see my post >> >>>>>> with photo, at the CR4 forum. >> >>>>>> >> >>>>>> http://cr4.globalspec.com/thread/55751/Lightning-Arrestor#comment579837 >> >>>>> You rate 3 "good" answers out of 14. That site has very high >> >>>>> standards! >> >>>>> >> >>>>> Why not use the lightning to heat water? The impedance match is >> >>>>> potentially better, and it's easy to store hot water. We could throw a >> >>>>> neighborhood hot-tub party after every strike, every 40 years or so. >> >>>>> >> >>>>> We don't get lightning here. I kind of miss it. >> >>>>> >> >>>> I don't miss it, seen to much electronics come to grief from it. Hey, >> >>>> why don't engineers at RF module manufacturers get it into their heads >> >>>> that the first part after the antenna jack has got to be an inductor to >> >>>> ground? Anything else will eventually go *PHUT*. >> >>> >> >>> Yawn. >> >>> >> >> T'is what I did when I just encountered the umpteenth module where that >> >> was done wrong :-) >> > >> > >> > Yawn, as in: WHAT ABOUT ALL THE RF EQUIPMENT WITH A DC VOLTAGE AT THE >> > INPUT CONNECTOR? >> > >> >> Gear out in the field typically never has that. I've done a lot of RF >> designs and even more re-designs by now. The number of units that would >> be DC-fed or have to provide LNA power was zero. Fact is, units deployed >> in the south or on the island won't even live through the first year >> with a nice big inductor to ground. Lightning strike into some fence out >> there, voltage surge, somewhere above 100V the input cap decides it's >> had it ... *POP* ... preamp and final TX amp are goners. >> >> Of course, if you design sat-gear that's different. > > > If they won't survive, why are there hundreds of Dish and Direct >satellite companies around here? Or line powered TV preamps? Active antennas (powered through the signal coax) are quite common on aircraft navigation systems too, so splitters etc. have to be specified with some care.
From: Archimedes' Lever on 14 Jun 2010 14:03 On Mon, 14 Jun 2010 13:56:25 -0400, Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >On Mon, 14 Jun 2010 03:04:03 -0400, "Michael A. Terrell" ><mike.terrell(a)earthlink.net> wrote: > >> >>Joerg wrote: >>> >>> Michael A. Terrell wrote: >>> > Joerg wrote: >>> >> Michael A. Terrell wrote: >>> >>> Joerg wrote: >>> >>>> John Larkin wrote: >>> >>>>> On 12 Jun 2010 07:16:54 -0700, Winfield Hill >>> >>>>> <Winfield_member(a)newsguy.com> wrote: >>> >>>>> >>> >>>>>> My Maxwell capacitors hard at work energy from harnessing lightning, see my post >>> >>>>>> with photo, at the CR4 forum. >>> >>>>>> >>> >>>>>> http://cr4.globalspec.com/thread/55751/Lightning-Arrestor#comment579837 >>> >>>>> You rate 3 "good" answers out of 14. That site has very high >>> >>>>> standards! >>> >>>>> >>> >>>>> Why not use the lightning to heat water? The impedance match is >>> >>>>> potentially better, and it's easy to store hot water. We could throw a >>> >>>>> neighborhood hot-tub party after every strike, every 40 years or so. >>> >>>>> >>> >>>>> We don't get lightning here. I kind of miss it. >>> >>>>> >>> >>>> I don't miss it, seen to much electronics come to grief from it. Hey, >>> >>>> why don't engineers at RF module manufacturers get it into their heads >>> >>>> that the first part after the antenna jack has got to be an inductor to >>> >>>> ground? Anything else will eventually go *PHUT*. >>> >>> >>> >>> Yawn. >>> >>> >>> >> T'is what I did when I just encountered the umpteenth module where that >>> >> was done wrong :-) >>> > >>> > >>> > Yawn, as in: WHAT ABOUT ALL THE RF EQUIPMENT WITH A DC VOLTAGE AT THE >>> > INPUT CONNECTOR? >>> > >>> >>> Gear out in the field typically never has that. I've done a lot of RF >>> designs and even more re-designs by now. The number of units that would >>> be DC-fed or have to provide LNA power was zero. Fact is, units deployed >>> in the south or on the island won't even live through the first year >>> with a nice big inductor to ground. Lightning strike into some fence out >>> there, voltage surge, somewhere above 100V the input cap decides it's >>> had it ... *POP* ... preamp and final TX amp are goners. >>> >>> Of course, if you design sat-gear that's different. >> >> >> If they won't survive, why are there hundreds of Dish and Direct >>satellite companies around here? Or line powered TV preamps? > >Active antennas (powered through the signal coax) are quite common on >aircraft navigation systems too, so splitters etc. have to be >specified with some care. They are usually NOT exposed. ie under a sheath, nosecone, or dome.
From: Joerg on 14 Jun 2010 14:23
Spehro Pefhany wrote: > On Mon, 14 Jun 2010 03:04:03 -0400, "Michael A. Terrell" > <mike.terrell(a)earthlink.net> wrote: > >> Joerg wrote: >>> Michael A. Terrell wrote: >>>> Joerg wrote: >>>>> Michael A. Terrell wrote: >>>>>> Joerg wrote: >>>>>>> John Larkin wrote: >>>>>>>> On 12 Jun 2010 07:16:54 -0700, Winfield Hill >>>>>>>> <Winfield_member(a)newsguy.com> wrote: >>>>>>>> >>>>>>>>> My Maxwell capacitors hard at work energy from harnessing lightning, see my post >>>>>>>>> with photo, at the CR4 forum. >>>>>>>>> >>>>>>>>> http://cr4.globalspec.com/thread/55751/Lightning-Arrestor#comment579837 >>>>>>>> You rate 3 "good" answers out of 14. That site has very high >>>>>>>> standards! >>>>>>>> >>>>>>>> Why not use the lightning to heat water? The impedance match is >>>>>>>> potentially better, and it's easy to store hot water. We could throw a >>>>>>>> neighborhood hot-tub party after every strike, every 40 years or so. >>>>>>>> >>>>>>>> We don't get lightning here. I kind of miss it. >>>>>>>> >>>>>>> I don't miss it, seen to much electronics come to grief from it. Hey, >>>>>>> why don't engineers at RF module manufacturers get it into their heads >>>>>>> that the first part after the antenna jack has got to be an inductor to >>>>>>> ground? Anything else will eventually go *PHUT*. >>>>>> Yawn. >>>>>> >>>>> T'is what I did when I just encountered the umpteenth module where that >>>>> was done wrong :-) >>>> >>>> Yawn, as in: WHAT ABOUT ALL THE RF EQUIPMENT WITH A DC VOLTAGE AT THE >>>> INPUT CONNECTOR? >>>> >>> Gear out in the field typically never has that. I've done a lot of RF >>> designs and even more re-designs by now. The number of units that would >>> be DC-fed or have to provide LNA power was zero. Fact is, units deployed >>> in the south or on the island won't even live through the first year >>> with a nice big inductor to ground. Lightning strike into some fence out >>> there, voltage surge, somewhere above 100V the input cap decides it's >>> had it ... *POP* ... preamp and final TX amp are goners. >>> >>> Of course, if you design sat-gear that's different. >> >> If they won't survive, why are there hundreds of Dish and Direct >> satellite companies around here? Or line powered TV preamps? > > Active antennas (powered through the signal coax) are quite common on > aircraft navigation systems too, so splitters etc. have to be > specified with some care. > Then there has to be an inductive path to ground farther upstream, at that amp. In aircraft electronics such stuff is usually done correctly and they have to follow stiff standards. Other areas, not so much, and there lots of them screw it up. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |