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 Thunder storm with lots of lightening and the STC A150 table gram.
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 Return to top of page · Post #: 1 · Written at 6:02:48 PM on 12 July 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 645

Well a double light show how about that!!
Was listening to our STC A150 table gram and every time a bolt of lightening occurred a blue flash came out of the A150 . Dog freaking out as he now does now he is in his senior years . Tried to look where it came from but every time I went to See how BoBo was getting on who had moved into the ensuite shower recess another bolt of lightening occurred and wife Robin said the radio did the same blue flash. Storm over radio back to normal dog out of shower recess. I can only think it was due to power surges .
Not many people around here get a double light show.


 
 Return to top of page · Post #: 2 · Written at 6:24:56 PM on 12 July 2020.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1993

Owww Radiograms and lighting don't mix well


 
 Return to top of page · Post #: 3 · Written at 6:27:51 PM on 12 July 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5997

Lightning can very easily destroy electrical equipment.

I once worked for an electrical engineer who had lots of memorable sayings, one of which was "Man makes lightning suppressors and God laughs".


 
 Return to top of page · Post #: 4 · Written at 6:43:43 PM on 12 July 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 645

I guess I should have turned it off which was my wife's advice.


 
 Return to top of page · Post #: 5 · Written at 7:05:26 PM on 12 July 2020.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1993

There is a member here and I remember reading his post ,maybe a year ago or more perhaps, you guys may also remember the post? Anyway he restore a old valve Radio back to prime and was doing something around the house , When a thunderstorm hit!
Clap, clap clap, he ran to unplug the radio but it had already taken a surge hit and damage it ..
I'm sure you guys must remember the post.

Pete


 
 Return to top of page · Post #: 6 · Written at 10:17:47 PM on 12 July 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1895

A direct lightning hit can do Very Strange Things.

In the mid 90s we had an office in Headland Rd Brookvale, alongside the top phone tower.

TV antenna was a 2 element Yagi mounted 30cm above the metal roof but with clear line of sight to the TV towers.
Cable from it went into an equipment rack 2 floors below. We also had a mix of UTP and coax ethernet running around the place.

The TV antenna was hit one night, despite it being at least 25 metres lower than the nearby phone tower and lower than the aircon unit next to it. We came in the next day to find everything in the rack dead. All coax NICs were taken out, UTP NICs and router ports still all good. AV router (my design) latched up, power supply in foldback. A power cycle fixed it!

But the strangest thing was the coax cable to the antenna. It was O/C, with little pinholes in the jacket along the entire approx 30 metre run. When we cut the cable open, there was nothing there! Just the outer jacket! The contents of the cable had vapourised and disappeared through the pinholes in the jacket. Same with the antenna balun, when the cover was unclipped it looked like there had never been a balun in there!

Strange and unpredictable.


 
 Return to top of page · Post #: 7 · Written at 11:42:28 PM on 12 July 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4329

I have said many times that here, in granite country, lightning is a constant and recurring problem and has been since day one when the family moved here in the 1870's. Since that time there are trees that have been killed, turned to petrified wood, and split in half by it. It has killed one person and one bolt hit a new metal LV power pole a couple of hours after it was put in place. It also burnt a contact of a 20A contactor whilst still having enough energy to blow around 140 fuses in the local RAX. One 22KV power line aerial had to be repaired after it damn near cut it in half. It was a Zeus fire ball that split the tree, prior to that it went inside the house, down the passageway & out before finding a target.

I have had a couple of sets, one an Astor RK Table-gram, where it had been hit. Every passive component had to be replaced: Only valves & Transformers survived. On one occasion an electrician doing a job on the LV overheads (now underground), just stepped of a ladder & there was a clap of thunder in the distance & the lightning arrestors on the supply transformer rattled. On the odd occasion its fascinating watching the power lines & radio antennas trailing St Elmo's fire.

The bench antenna (40+ Metres) has a separate ground to the mains. The mains one, at the distribution box (four lines out) is in an old creek bed. There is a neon tube across the antenna to ground. The antenna is tied to ground when there is lightning, or often when not in use, as that acts as an umbrella to discharge lightning.

As described before The electric fences have lightning arrestors and the rest, including the mains electric fence energisers have surge arrestors. Some of these are old inductive filter units that have been modified, or home made jobs. These are designed to try & get rid of the RF that rides on the lines & gets into the radios, even via transformers and the ever present spikes from lightning & such. The incredible I witnessed was a summer storm. It hit a grain silo ran along the Std. gauge rail for several hundred metres,

Since the advent of RCD's I changed design & so did the commercial lot, a long time after I did. The RF & a bit of other garbage is reduced by placing line caps thus: 0.1mfd across the line N & A then not exceeding 0.01mfd one from Active to Ground and one from Neutral to ground. A common arrangement for many suppressors on mains electric drills when RFI mattered.

The variation due to RCD's sees the Neutral float after the RCD. Now the mod was that one added a second MOV: This from Active to Ground / Earth on the load side. And this is also what the big boys have done. So you have one across the line & the added one.

This actually works as a faulty solar inverter proved. One lives in hope that the broadside MOV absorbs a lot of the surge or spike, whilst the other one, doing similar unbalances the line causing the RCD to kill the circuit. Before the Inverter was replaced the one on the TV had tripped its circuit a couple of times (modified commercial inductive filter) and one in this workshop (non-inductive) had tripped a couple of times. These filter styles I have used for over 30 years all are now the latter types.

As said, many Surge type power boards have the MOV's this way but no caps.

Funny story: Darwin Awards. Idiot in the middle of a lake in a tinny in a storm. Stands up "proclaims Lord take me" and he obliged.


 
 Return to top of page · Post #: 8 · Written at 9:26:38 AM on 13 July 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 645

Yes it is frightening stuff. When I worked for a broadcast TV network I often had to go to knights Hill,top of Robertson in a thunderstorm very frightening the cows in the surrounding paddocks were sometimes killed by it.
I was more concerned with the dog than the radio and I actually initially had not associated the radio flashing and the lightening flashing .
Radio survived ok will turn them off next time.


 
 Return to top of page · Post #: 9 · Written at 9:53:52 AM on 13 July 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4329

If you have long wire antenna/s disconnect. Knife switches that they used to use on 300 ohm cable are good as a DPDT meant you could have " live, disconnected and grounded". One long-wire antenna here is 70metres long.

Bench is terminals with shorting cable.

A spark plug makes a spark gap.

Re last comments MOV's etc should be inside a box that is fire proof and will not allow flying particle escape. MOV's have been known to explode (as have caps).

Marc


 
 Return to top of page · Post #: 10 · Written at 10:11:22 AM on 13 July 2020.
Vintage Pete's avatar
 Location: Albury, NSW
 Member since 1 May 2016
 Member #: 1919
 Postcount: 1993

I was in the salt flats in South Australia desert in the late 90s ,photographic the flat salt plains and a huge thunderstorm came along.
I could see it in the distance approaching so I started timing the time difference between the thunder and the lightening and figured out it was coming closer ,not ending.
So I set up my tripod and got ready for it ,Then the dark clouds came in and the lightening started Arcing on the desert floor.
There are no trees! I was the highest point on the salt flats, so I layed flat on the ground just raising my hand to fire off the camera while timing it ,so knew when the next Arc was due.
I got some great shots of the lightening hitting the ground all shot on trany,Then within a few minutes the complete area just flooded....
I was glad to get out, because I was not in a 4x4 drive on that day ,I was in a Honda.
Mother Natures beauty puts on a good show when she is in a mood!

Pete


 
 Return to top of page · Post #: 11 · Written at 12:54:36 PM on 13 July 2020.
Irext's avatar
 Location: Werribee South, VIC
 Member since 30 September 2016
 Member #: 1981
 Postcount: 398

During the 70's as a radio tradesman I did CTV repairs in customers houses.
When a set had been hit by lightning the damage varied from vaporized baluns to tracks missing on power supply boards or destroyed RF amps in the tuner.
There was no rhyme or reason to the damage but it was usually spectacular.
The thing that amazed me was pcb tracks just ceased to be with no sign of them ever having been there.
As a Broadcast tech in the 90's we were covering a Golf match in Coolum with several OB Vans located around the golf course linked together by "Poly cables" which were a cable consisting of multiple video and audio paths for Vision, Audio and talkback between each OB location.
A storm went through and there was an almighty crack with the flash and the bang occurring simultaneously, so right outside the van.
All we could hear from that moment on was load humming coming from all the talkback panels in the van and all vision feeds from the other OB locations now missing.
It blew up all of the input OP amps in our talkback system as well as multiple video distribution amps (VDA's) and some inputs to the audio mixing desk.
Fortunately it was a set up day but we worked well into the evening getting as much going as our supply of spares would allow.
If you get hit by lightning all bets are off!


 
 Return to top of page · Post #: 12 · Written at 1:44:58 PM on 13 July 2020.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6333

When I worked at Gladesville Hospital all those years ago there were three cottages down the back near where Banjo Patterson's Restaurant is now. These cottages are (rumoured to be) on an ironstone reef and this used to attract more than the fair share of lightning in the area. When lightning would strike, it would pop all the light globes, forcing us to change them all the next day.

I am not sure if LED globes are just as susceptible or not.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 13 · Written at 11:11:52 AM on 14 July 2020.
Irext's avatar
 Location: Werribee South, VIC
 Member since 30 September 2016
 Member #: 1981
 Postcount: 398

LED globes are probably worse cause there is electronics to be fried as well.


 
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