Alpha Delta Switch Arc-Plugs

Gas Discharge Tubes

I recently bought a couple of Alpha Delta coaxial switches, and noticed they come with a built-in surge arrester which can be replaced after a surge. They call them “Arc-Plugs”. These are on sale at DX Engineering for $9.99 each. I thought that was a little steep.

When the switches arrived, I took at look to verify what these were, looking for part numbers, etc, and discovered they are actually Littelfuse CG21000 gas discharge tube surge arresters. These are a common component often use in telecommunications and other surge-prone areas of electronics.

These can be found online at Mouser or Digikey for around $2.99. All you would need to do would be to order the leaded variant, snip off the leads with a pair of cutters, and you’re good to go. After all, that’s what it looks like Alpha Delta are doing too.

I don’t know about you, but I like cheaper.

If you would like to know more about how these surge arresters work, check out this detailed PDF from Bourns:

Thanks to N5UWY for setting me off on this curiosity!



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  1. I’ve used A-D TransiTraps as long as I’ve had antennas outdoors. What I’m more interested in is how you would ever know that these are “bad” or “used up”. Do they fail-safe? If they do, would my antennas be, essentially, grounded?

    • Well, you piqued my curiosity – I had to go and find out. Check out the PDF that I attached to the post. Page 21 starts to talk about the life cycle of these devices. Cheers!

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