Basejumper.com - archive

Was scouting a tower, AM guyed, and saw this at the base. Any ideas what it is?

I'm sketched about getting on board an AM tower but this girl is a few miles from my house in a big field screaming at me.

I believe it's a lightning ground. There are some good threads in the past here, do a search and you will probably find some other pictures and info too.

Do what you want, but I personally would not touch one of those things. There is an array I can see up the road, in a big ol field... not worth it to me though.

Wow, those bring back memories. We used to call them magician rings

Thank you for the info. I will let this one pass til I know it's off air.

All the information I have found on them is that they are Dual-Winding Isolation Transformers, or Lightning Transformers.

http://www.austin-insulators.com/radio/xfmr-d.html

http://www.austin-insulators.com/...Manuals/A-XFMR-D.pdf

I don't believe they are anything to be concerned about. There is one on one of my local A's:

http://imgur.com/BTp0zNX

However, mine is an FM freestander.

I would be more concerned about the AM and guyed (if it's short) features. I know someone who jumped the 'Blowtorch of the West' who claims he hasn't felt/thought the same since...

They are not lightning transformers they are lighting transformers. It's an isolation device to protect the circuit providing power to the lighting system on the antenna and the circuit providing RF power to the antenna from each other.

interesting. just out of curiosity how do they behave if/when the tower does get struck by lightning? do they arc?

They can definitely arc. That's why they have the two small orbs off to the side with an air gap between them, so that any arcing that happens is between those, bypassing the windings of the transformer.

The arc doesn't necessarily have to be due to lightning either. If the atmospheric conditions are just right (or wrong depending on how you look at it) you can get arcs from the RF power going into the antenna.

AM towers are mast radiators. That is, the tower itself is the antenna. The tower therefore has to be isolated from ground. If the tower were grounded, the signal being transmitted through it would have a short circuit to ground. This is why you can't just climb onto an AM tower while it's live. If you touch the tower while still standing on the ground, your body becomes a conductor to ground. I wouldn't recommend jumping an AM antenna.

Thanks for pointing out the typo. Yes, a lighting transformer - as confirmed by the links in my post.

You have better objects available,

the extra miles driven are worth

avoiding the extra radiation

I know now. And its off the list. But if it was to ever shut down.......

It's my understanding if they are shut down, they can still reach out and grab you if they are not grounded out...