Kim,
It's generally recognized that glass tubes have poor shelf life due to slow
leakage. I have heard many reports of this from people I trust.
They will last much longer if the plate gets hot at least a few times a year
so that any leakage can be gettered away. For tubes in regular use rather than
on the shelf, it doesn't seem to be a problem, but it makes it difficult to
stock up with spares. Many amateur users rotate their shelf stock into the amp
at least once a year.
Is the 3-500Z used much outside of ham radio today? If so, who are the
primary users?
73,
Cathy
N5WVR
--------------------------------------------
On Tue, 6/6/17, Kimberly Elmore <cw_de_n5op@sbcglobal.net> wrote:
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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