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Author Topic: 3-500 tubes life span  (Read 1913 times)
K9FON
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Posts: 1012




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« on: October 10, 2008, 03:56:28 AM »

With proper drive and care what is the average life span for a pair of 3-500 tubes?
The tubes in my Swan MK II are the original tubes installed by Swan in 1976! And i get full out on all bands.
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K0BG
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« Reply #1 on: October 10, 2008, 05:59:54 AM »

You almost answered your own question. And the answer is, no one really knows. The life span of yours is typical in a lot of ways, if, as you point out, you don't over drive and abuse them.

The big killer of glass bottled tubes is their pin seals. If you use the tubes regularly, you don't have too much of a problem with the seals.

Alan, KØBG
www.k0bg.com
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WB0SND
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« Reply #2 on: October 10, 2008, 07:43:22 AM »

Watch the grid current.  That's what kills 'em  Normally you wouldn't want to exceed 130 mA per  tube.
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KB9CRY
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« Reply #3 on: October 10, 2008, 09:02:56 PM »

10-30 years.
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W8ZNX
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« Reply #4 on: October 11, 2008, 01:35:14 AM »

not just grid current

keep fil voltage where it should be

3 years ago replaced a 3-400Z
that had been in service since 1965

was still working
just getting soft
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K9FON
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« Reply #5 on: October 11, 2008, 10:34:48 AM »

well i guess im lucky then.
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W3LK
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« Reply #6 on: October 11, 2008, 11:42:27 AM »

I have an AL-80A with a low, four-digit (the first digit is a zero) serial number and it has, as far as I know, the original Eimac tube. I've had it six years and prior to that it was in a MARS station.

It still puts out 900+ watts on SSB with 80w drive.

73,

Lon - W3LK
Naugatuck, Connecticut
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
K9FON
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Posts: 1012




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« Reply #7 on: October 12, 2008, 04:15:46 PM »

I know several hams that own amps that have 3-500 tubes in them and no one has ever had issues. One local ham has a Kenwood TL 922A that he bought new in 1980 and he has never even had the screws removed from the case!  
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