>
>On Mon, 16 Mar 98 16:14:43 -0800 Rich Measures <measures@vc.net> writes:
>>>SNIP
>
>>>I am glad you stress that it is only an opinion Rich.
>>
>>What is your opinion as to why a virtually new Eimac 3-500Z would
>>generate a big bang and sustain a grid-fil. short?
>
>>>BTW, what was the date code on that tube and did it come from the
>>NY/NJ
>>>area?
>>>
>>date code 8939, NY was where it was shipped from, Carl, although I do
>>not
>>from which dealer the "new" TL-922 came from.
>
>
>With that date code it does not suprise we.....YOU, I and others have
>mentioned many times that Eimac had definite problems with 3-500Z's in
>'89.
Only in relation to defective anode cooler welds, not to bent filament
helixes.
>I can only relate a few of the hooror stories of the hams that
>bought '89 tubes for spares only to have them go bang when used several
>years later.
>Actually I commend your honesty about the date code Rich...others would
>have tried to hide it.
>
By what mechanism does an allegedly defective tube damage the parasitic
suppressor R and blow the grid choke?
>I was buying 3-500Z's at 100 a time from Eimac then and even right out of
>the box I had a high failure rate. It was around 1992 or so that I really
>got feedback from those ...many good friends...that had decided to use
>their "spares". and having big bangs.
>It was also at that time that I started a serious evaluation of all the
>Chinese versions. Today...1998 I only buy Chinese. Failures are
>virtually zero..
>
>Rich..and others ..it is my "opinion only"...that a huge majority of
>Eimac 3-500Z failures are due ONLY to poor quality tubes...NOTHING ELSE.
>I fail to see any failures with Amperex (1968 and later) or good Chinese
>(1994 and later) versions that even approximate the Eimac experiences. I
>stress the word ANY.
>
I have tested Amperex and Chinese [Penta] tubes that failed from a bent
filament helix.
>I suspect that I know the source of those tubes and amp which is why I
>asked.
>
The two, new tubes came with the new TL-922.
>
>Bang..yes...parasitic..highly doubtful.
>
Only if you can explain a plausible alternative scenario based on the
circumstantial evidence. . Your serve, Carl.
cheers
Rich...
R. L. Measures, 805-386-3734, AG6K
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