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Eimac 3-500Z Tubes




 
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WB4YVO
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« on: July 21, 2018, 07:15:12 PM »

All, I think here is the best place to ask this.. I have OLD SB-220 Heathkit amp.. It hasn't been in operation for about say 10 Years.. Maybe not quite that long..I plan on upgrading the HV Caps and anything else it may need.. But question is I have a pair of tubes 3-500Z that have been sitting on my self for around 10 years.. How do I make sure that they still work.. I heard you run filament only for awhile.. But others say that doesn't work.. So maybe I need some kind of a Test jig to build that would apply the right voltages to make sure it working??

Anyone have a circuit that I could build??

Thanks
Skip..

 
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Patrick J. / KD5OEI
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« Reply #1 on: July 21, 2018, 11:17:43 PM »

There's a process called gettering. I think that is what you might do. Lots of info on that, as to voltages, precedures, etc. and any test gig would be pretty simple, maybe even using the SB-220 as the test sockets etc.
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« Reply #2 on: July 22, 2018, 09:18:41 PM »

Google 'radio tube reconditioning' .... It is important that you have control of the current drawn .... putting a gassy tube in a functional linear amp will likely give a bright flash and now nonfunctional amp .... use the instructions to degas the tube for decent operation
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« Reply #3 on: July 22, 2018, 09:22:47 PM »

I was not suggesting letting the SB-220's plate supply run free. Hope that was not the impression. More like, there's a nice tube socket and fan.. and some temporary hackery might do to make use of that convenience.

but yes as BFS said .
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #4 on: July 30, 2018, 11:11:13 AM »

Quote
But question is I have a pair of tubes 3-500Z that have been sitting on my self for around 10 years.. How do I make sure that they still work..

The only way to find out is to run them.

While you are replacing the PS filter caps, you might also want to make some upgrades as per below:


Phil - AC0OB


* Heath SB-220 Modifications.pdf (25.9 KB - downloaded 26 times.)
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