>Hello Group !
>
>I have been following the discussion on tubes and I find it very
>interesting.
>I am in no way an expert, but have had my share of 8877's, 3-500Z's.
>
>I can say I did experience a problem with a 8877 in an old Ameritron AL-1500
>I had some years ago, and replaced it with a "Pull" that I purchased
>and was back on the air. I did not have the skill to check the tube
>to even know if it was bad. I figured since it had lower then expected
>output, it was time to go.
** Low P-out is a symptom of gold-sputtering - wherein gold evaporates
from the grid and lands on the cathode. Since the gold poisons cathode
emission, which lowers I-anode and power output.
- I would like to test the tube you pulled and try to find out what's
what. I will return tube via Priority Mail. If the problem is
gold-related, it is not difficult to move the gold particles from the
cathode into the tube base by tapping with a hammer in the vertical
plane. This restores emission and the tube can be used as a spare
provided the base is down.
- An autopsy photo of a gold sputtered 8877 removed from an AL-1500:
http://WWW.VCNET.COM/measures/8877.gs2.JPEG
The Funderburg (W6IHA) gold sputter test is described on my Web site.
cheerz, Keith
>
>I am curious is some of the problems in the past that have made company's
>switch to the Russian Tubes, are do they also have similar problems.
>
>I own 2 Alpha-99 Amplifers, and have been gradually accumulating
>4CX800's as spares with the fear that in the future when I need
>some they will be expensive to purchase, or not available.
>
>Would appreciate any comments on my strategy of purchasing
>tubes and putting them in storage.
>
>Thanks,
>Keith, K4KAL
>
>
>
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>
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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