[Amps] 1993 Vintage 3-500z

Tue Jun 6 13:17:22 EDT 2017

That process will do nothing for the 3-500 family.

Since the ongoing gettering process requires anodes to be run at color at 
least 3-4 times a year from new and a lot more when they have sat for years 
an entirely different process is needed. Running filaments only does nothing 
but waste 75W per tube. Indirect heated cathode tubes respond well to 
filaments only.

In older amps such as the SB-220, Drake L4B, aHunter 2000C, and others with 
the pre 1500W OUTPUT FCC rule compliance CW/SSB switch it is often possible 
to run them at color at the lower HV position which is just above the 
threshold of creating an internal plasma arc. Running as an AM linear, out 
of tune on 80/160, shorting the bias diode when used, can all create that 
nice red/orange glow.

If the tube arcs at that voltage then a method to bring the HV below 1200V 
and positive biasing the tube MAY work but it will also likely take lots of 
hours. Just as a test Ive had a few take up to 2 days in the basement during 
winter so the electricity use wast wasted.

A regettered tube will require less time before it needs it again if it was 
a real dog to start with. I use a pair in a 60's Hunter 2000C regularly as 
an AM linear in the SSB position so they get a bright orange and that has 
kept them happy for about 3 years sofar. My bought new in 1986 LK-500ZC wih 
the original Eimacs has been beat on hard in contests, pileups and on AM and 
hasnt burped yet.and will still do an easy 1200W.

The only ceramic-metal tube Im aware of that had actual seal leakage is the 
4CX300A and that caused the USAF and others a lot of grief and money.

Carl

----- Original Message ----- 
From: "Chris Hays" <chris at chrishays.com>
To: <amps at contesting.com>
Sent: Tuesday, June 06, 2017 12:39 PM
Subject: [Amps] 1993 Vintage 3-500z

> Not necessarily, but you need to bring them up carefully.
>
> If you have or can get access to a hi-pot tester, that might be the best
> first step.
>
> However, if it were mine:
>
> 1. Remove one of the tubes so you aren't trying to deal with two at a 
> time.
>
> 2. Run filaments only for 3 to 4 hours.
>
> 3. Bring plate voltage up slowly (you will need to get a variac connected 
> to
> the HV primary so filaments will stay hot. Also, you should put a non-slow
> fuse in series in case it decides to flash over.
>
> 4.  When you get to a kilovolt or so, carefully apply some drive gradually
> bringing it up (obviously you need a dummy load here that can take the 
> power
> for a period of time)
>
> 5. Bring up drive watching plate current carefully.
>
> 6. If it arcs, back down and repeat.  One thing I have learned is that if
> the tube arcs without destroying the grid or filament, the arc will have 
> the
> effect of cleaning some of the gas out of the tube (I know this doesn't 
> make
> sense, but years of bringing up really big tubes that were gassy has
> confirmed this). The fuse is very important here to prevent damage to the
> tube and the power supply.
>
> 6a. If it continues to flash over after a few tries, you might want to
> consider that tube a lost cause.
>
> 5. Once you get drive to where the tube is saturating (as in more drive 
> does
> not yield more output) leave it there for a time. If the plates glow all 
> the
> better.
>
> 6. Start slowly raising the high voltage a bit at a time, adjusting drive
> until you are at where the tube is at rated output (remember this is one 
> of
> two, so it will be half the normal output of the amp).
>
> 7. If you get to the point where you can get the plates reddish, leave it
> there for an hour or so.
>
> 8. Repeat for the second tube.
>
> Your mileage may vary.  I'm sure others will comment and may have more
> elegant methods.  If you aren't comfortable doing this I suggest getting
> some help.  Remember, high voltage kills!! Be careful!!
>
> Chris, AB6QK
>
> ORIGINAL MESSAGE
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 6 Jun 2017 10:20:47 -0500
> From: Joe <nss at mwt.net>
> To: Catherine James <catherine.james at att.net>, Amps group
> <amps at contesting.com>, Kimberly Elmore <cw_de_n5op at sbcglobal.net>
> Subject: Re: [Amps] 3-500Z cool down time
> Message-ID: <fdf26300-3f43-cd29-249d-32d95dff9146 at mwt.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> 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
>>
>
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