[Amps] 3-500Z cool down time
Carl
km1h at jeremy.qozzy.com
Tue Jun 6 13:30:28 EDT 2017
----- Original Message -----
From: "Carl" <km1h at jeremy.qozzy.com>
To: "Charlie Young" <weeksmgr at hotmail.com>; "Joe" <nss at mwt.net>; "Catherine
James" <catherine.james at att.net>; "Amps group" <amps at contesting.com>;
"Kimberly Elmore" <cw_de_n5op at 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 at hotmail.com>
> To: "Joe" <nss at mwt.net>; "Catherine James" <catherine.james at att.net>;
> "Amps group" <amps at contesting.com>; "Kimberly Elmore"
> <cw_de_n5op at 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 at mwt.net>
> Sent: Tuesday, June 6, 2017 11:21 AM
> To: Catherine James<mailto:catherine.james at att.net>; Amps
> group<mailto:amps at contesting.com>; Kimberly
> Elmore<mailto:cw_de_n5op at 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 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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