----- Original Message -----
From: "Carl" <km1h@jeremy.qozzy.com>
To: "Charlie Young" <weeksmgr@hotmail.com>; "Joe" <nss@mwt.net>; "Catherine
James" <catherine.james@att.net>; "Amps group" <amps@contesting.com>;
"Kimberly Elmore" <cw_de_n5op@sbcglobal.net>
Sent: Tuesday, June 06, 2017 1:25 PM
Subject: Re: [Amps] 3-500Z cool down time
I suspect that Eimac put a lot more effort into conditioning the tubes back
then. Pull a better vacuum and the breakdown voltage increases.
Ive hi-potted some beyond the 13KV capacity of my tester. OTOH youre lucky
to get 8KV out of Chinese versions.
Carl
----- Original Message -----
From: "Charlie Young" <weeksmgr@hotmail.com>
To: "Joe" <nss@mwt.net>; "Catherine James" <catherine.james@att.net>;
"Amps group" <amps@contesting.com>; "Kimberly Elmore"
<cw_de_n5op@sbcglobal.net>
Sent: Tuesday, June 06, 2017 11:36 AM
Subject: Re: [Amps] 3-500Z cool down time
I have seen some 3-500 tubes affected by long storage and some not.
In 1995 I bought a new matched pair of Eimac 3-500 tubes. The date code
on the tubes is 1994. Once in the early 2000’s I tested these tubes and
they were OK. Pulled them out and placed them back in storage; I was not
running an amp that used them. Fast forward to about 2011 and they were
both gassy when put into an AL-82. Arc city. I don’t know if they can
be rehabilitated or not by bringing up the HV low and slow and biasing
them to conduction so the plates heat up. I have not tried that yet, but
plan to do so soon.
On the other hand, I bought an old SB-220 from a CB operator back in the
early 1990’s. The Eimac tubes in it have 1973 date codes. This amp was
never fired up from 1996 until it was converted to 6 meters in 2010.
These tubes are fine, and still make 1400W on 6 meters. No arcing at all
even when first fired up.
So, I think it depends on the individual tube.
73 Charlie N8RR
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows
10
From: Joe<mailto:nss@mwt.net>
Sent: Tuesday, June 6, 2017 11:21 AM
To: Catherine James<mailto:catherine.james@att.net>; Amps
group<mailto:amps@contesting.com>; Kimberly
Elmore<mailto:cw_de_n5op@sbcglobal.net>
Subject: Re: [Amps] 3-500Z cool down time
So this SB-220, that has been sitting since 1993, the tubes are most
likely toast?
Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 6/6/2017 10:14 AM, Catherine James wrote:
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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