The initial use was for ISM amps.
Except for a short time in the late 80's Eimac 3-500Z's had no seal problems
and I still have a few with 70's date codes that are fine.
The Chinese versions have been OK so far.
Another tube that eventually became a leaker is the 4-1000A.
Eimac and Chinese 3-500's are always prone to outgassing from the anode
which has absolutely nothing to do with seal leaks to the outside air.
Unless you are prepared to go thru a regular regettering process then it
becomes more of a ues them or lose them scenario.
Carl
----- Original Message -----
From: "Kimberly Elmore" <cw_de_n5op@sbcglobal.net>
To: "Catherine James" <catherine.james@att.net>; "Amps group"
<amps@contesting.com>
Sent: Tuesday, June 06, 2017 10:56 AM
Subject: Re: [Amps] 3-500Z cool down time
The biggest issue with the 3CX1200 is appears to be that it's simply not
used in much outiside of ham radio. I'm not sure what the original design
application was intended for, but I'm pretty sure it wasn't just for
amateur use.
As for glass tubes, I know that some are notorious for leaky seals, but I
thought such was rare. Is it a significant problem with the 3-500Z?
Kim N5OP
From: Catherine James <catherine.james@att.net>
To: Amps group <amps@contesting.com>
Sent: Tuesday, June 6, 2017 9:04 AM
Subject: Re: [Amps] 3-500Z cool down time
Given that ceramic tubes appear to last longer on the shelf with less
leakage than glass, it's a shame that there isn't a ceramic tube in the
price/performance range of the 3-500Z. It would be well worth paying, say,
10% more for ceramic. But the actual cost multiplier is much higher than
that, so glass tubes will continue to rule at the low end (i.e., far below
legal limit).
73,
Cathy
N5WVR
--------------------------------------------
Kimberly Elmore <cw_de_n5op@sbcglobal.net> wrote:
True enough; I was simply
statingthat the 3CX1200 is a ceramic replacement for a glass
envelope. It's a fine tube, though it requires a fair
bit more drive. That is, aparently, the price paid for a
high grid dissipation rating. It's easier to drive when
running 4 kV B+, though. At that voltage, I never fail to
acieve full output with a 100 W rig on any band.
Kim N5OP
From: Bill Turner <dezrat@outlook.com>
To: Amps group <amps@contesting.com>
Sent: Monday, June 5, 2017 9:32 PM
Subject: Re: [Amps] 3-500Z cool down time
------------ ORIGINAL
MESSAGE ------------(may be snipped)
On Mon, 5 Jun 2017 20:48:40 -0500, Kim
wrote:
>The 3CX1200 is a
ceramic version of the 3-1000Z. I have an amp that uses one
and it's ready in under 10 s.
>Kim
N5OP
REPLY:
Yes, but that's a very
expensive tube. I was thinking of a ceramic
3-500Z for the same price as glass.
For what they are asking you
might as well get an 8877. Different
socket
but lower drive and more output.
73, Bill W6WRT
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