I purchased a new old stock Eimac 3-500Z to be a spare tube for my
AL-80B. Production was abt 1985. Inserted into the amp there was a blue
glow in the tube that was never present with the usual Pride tube. I
dared not to key the amp since I suspected the tube to be soft. Let it
on and after some time the blue glow was weaker. After about 20min there
was almost no blue glow.
Then I keyed the amp and let som power in. It worked fine also with more
power. There was no pop or bang even with max power, so a 15-20 years
old Eimac 3-500Z seems to require abt. 20 mins with heater on for "burn
in"
Helge
LA6MV
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
On Behalf Of ab5mm
Sent: 19. juni 2004 04:18
To: amps@contesting.com
Subject: [Amps] Tube Burn In Question.
The 20+ year old 3-500Z Eimacs have lost their brilliance. I finally
broke down and purchased a new pair to go into the Henry 3K-A today at
HAM-COMM.
My question is how should I "burn in" the tubes?
How many hours?
Only filament and blower on? (I did the mod to cool the pins)
Filament voltage? (I can vary it)
And finally, is there a general consensus on whether or not some portion
of the burn in time should include plate voltage (no drive, just idle
current? (I can vary this also)
As always, Thank You for the input.
Steve
AB5MM
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