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>From: km1h@juno.com
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>To: amps@contesting.com
>Cc:
>Subject: Re: [AMPS] 3-500Z storage
>Message-ID: <19970225.092000.9887.26.km1h@juno.com>
>References: <3.0.32.19970224172350.00a213e8@pop.uky.edu>
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To: <amps@contesting.com>
>Date: Tue, 25 Feb 1997 09:18:32 EST
>
>Bill, the only cure I have heard that works for gas in a tungsten
>filament tube is to run the tube with a bit of color (with full air) and
>periodically checking. I have no idea how effective this is with varying
>amounts of gas.
>
>The storage issue came up around 1992-93 or so when a unusual number of
>horizontally stored NIB 3-500Z' s were reported shorted upon turn-on.
>Many guys called EIMAC for warranty replacement and were told that those
>tubes should only be stored vertically. This was reported on packet and
>in various contest newsletters then. Other comments notwithstanding, I
>would tend to lean to the manufacturers suggestions and play it safe. It
>was also around this time that EIMAC became very strict with the 1 year
>from date code warranty policy. I can't say for sure but there were a lot
>of rumors flying around about some cost cutting manufacturing changes,
>quality control and other plant problems.
>
>Bringing the PS up with a Variac is a good idea. If one is not available
>you can use a 120V line with the amp wired for 240V as a means of
>reducing the input current shock. The old light bulb in series with the
>AC line trick works well also. After only a 3 year sitting period, the
>odds of cap problems are slim.
>
>There is one procedure that should be followed with old or new PS caps.
>That is to measure the voltage drop across each one. There should be
>about a 10% maximum variation and with none exceeding the cap ratings. I
>have observed even new out of the box computer grade caps, from the same
>date code run, that are way out of tolerance....by as much as 50-60%.
>
>Heat is a real killer in that Drake PS and a muffin fan would be a big
>plus. Almost forgot.....At least check those 100K carbon equalizing
>resistors for 5% tolerance. Better still replace with 3W metal oxide.
>
>GL.....Carl KM1H
>
>
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