[Amps] 3-500Z cool down time

[Joe]

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 at 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 at att.net>
>    To: Amps group
>   <amps at 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 at 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 at outlook.com>
>     To: Amps group <amps at 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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