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   Neil G4DBN (g4dbn@mastodon.radio)'s status on Tuesday, 02-Jan-2024 05:53:50 JST Neil G4DBN

   Look what followed me home from that ebay. Original early 1950s AN/APX-6 Identification Friend or Foe transponder. These were using during the Castle nuclear tests as well as in many thousands of aircraft, with a base station mounted on the X band radar systems. In the late 1950s, many were bought as war surplus by radio hams and converted to the 1.3 GHz/23 cm band. It makes over a kilowatt from a pulsed disc-seal triode and has a radioactive T/R switch and three explosive Destructors

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     Neil G4DBN (g4dbn@mastodon.radio)'s status on Tuesday, 02-Jan-2024 05:54:48 JST Neil G4DBN

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     • M0KHR

     @M0KHR Uh-huh. Yup. Not a lot of nasties in 0.2 microcuries though, even when it was new, so now only 6 femtocuries left. 0.2 microcuries is about 7 kBq, so by now, the activity is about 2e-15 times that, so well under one decay per second. Although those are mostly 310 keV electrons, the products then decay by emitting gamma rays at 1.2 and 1.3 GeV so it's a bit spicy

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     M0KHR (m0khr@mastodon.radio)'s status on Tuesday, 02-Jan-2024 05:54:50 JST M0KHR

     in reply to

     @g4dbn C-60!!! Isn't that one of those "drop and run" parts! :)

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     Neil G4DBN (g4dbn@mastodon.radio)'s status on Tuesday, 02-Jan-2024 05:54:51 JST Neil G4DBN

     in reply to

     • M0KHR

     @M0KHR Nope, it has a 1B40 Argon-filled plasma tube with a 0.2 microcurie Cobalt-60 source. When it is in a strong RF field, the Co-60 and bias voltage cause a plasma to form, which shorts out the intermediate cavity between the 1 kW TX and the delicate crystal diode RX cavity. It can take 500+ watts, but only for a microsecond, at about 1000 pulses per second. Problem is that Co-60 half-life is only 5.3 years, so after a decade, it stops working, and by now, nowt left. https://lampes-et-tubes.info/mwtr/1B40.pdf

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     M0KHR (m0khr@mastodon.radio)'s status on Tuesday, 02-Jan-2024 05:54:53 JST M0KHR

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     @g4dbn "radioactive T/R switch " radium paint, I presume?