>
>How did you determine that the 8877 was a dud, due to gold-sputtering ??
The negative anode leakage was virtually zero. The positve anode leakage
was higher.
>Did
>you disassemble the tube, cut it in half or hi pot test only ??
I removed the anode cooler by cuttin the sheet metal just above the
solder joint to the ceramic insulator. There is one gold blister on the
lower half of the grid.
>
>You used the word apparently failed, do you know that to be the actual
>reason for the fail ???
>
No one knows the actual reason for failure. One makes measurements,
makes an educated guess, and autopsies the tube. If there had been no
blister, then loose gold could not have been the culprit.
>I know several people who have AL-1500 amplifiers for several years and
>they have never had to replace the 8877 in their amplifiers and they use
>them every day.
Some oscillate, some don't.
>Is the failure of all these tubes that you have an operator
>issue and not really a issue of design ???
Doubtful. Eimac said that gold plating evaporates during an oscillation
condition. I have never seen a case of gold sputtering that did not have
UHF tracks.
>If the AL-1500 was truly designed so poorly than Ameritron would have had to
>pull the amplifier from their product line due to the thousands of 8877's
>tubes that they would have had to replace during the warranty period.
>
? Ameritron gets needed replacement tubes free from Eimac. The warranty
dept. at Eimac reportedly does not test for gold sputtering. If a tube
has leakage, it goes in the scrap bin and a new tube is provided.
>It is not a perfect world and I don't think that anyone can make an operator
>proof amplifier, except for Rich
There's always a chance that some turkey will replace the 2A screen fuse
with a 20A unit.
> and when he goes into his commercial
>production of his amplifier design, I will be one of his first customers. I
>want the perfect amplifier, so I have already started to save.
I gave it a passing thought, Pat. The Ugly Amplifier is a natural for
easy reproduction. The major difficulty is accurately cutting 1/8"
6061T6 plate. Industrial Metals in Burbank supplies aluminum and does
precision cutting. Svetlana can supply 8171s and sockets at a good
price. I can get a break from Jennings if I am a manufacturer and I
purchase 100 units. . . . . If I was younger and in better health, I
might go for it. However, operating a cash only business draws whopper
flies. For example, banks report deposits of more than three $100 bills
to the Feds. The story about banks only reporting transactions over
$10k is pure bull.
>
cheers, Pat
>-----Original Message-----
>From: measures <2@vc.net>
>To: AMPS <amps@contesting.com>
To: <amps@contesting.com>
>Date: Saturday, September 16, 2000 10:35 PM
>Subject: [AMPS] WTB kaput 8877 from AL-1500.
>
>
>>
>>The first 8877 dud I tested from an AL-1500 apparently failed from
>>gold-sputtering. (see 'A letter from Eimac' near end of my Web site) I
>>would like to purchase another AL-1500 dud and test it. // I am also
>>looking for a 3CX800A7 that failed in an Alpha.
>>thanks
>>
>>- Rich..., 805.386.3734, www.vcnet.com/measures.
>>end
>>
>>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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