[Amps] 3-500Z cool down time

Carl km1h at jeremy.qozzy.com
Tue Jun 6 12:45:26 EDT 2017


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 at sbcglobal.net>
To: "Catherine James" <catherine.james at att.net>; "Amps group" 
<amps at 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 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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