>> From: Rich Measures <measures@vc.net>
>
>> In commercial FM broadcast service, 8877s typically last 20,000 hours.
>> 33 months in amateur radio service probably amounts to under 500 hours of
>> use. During the last ten years, I've tested a number of kaput 8877s
>> that were removed from Alpha 77s. Most of the failures were caused by
>> gold sputtering from the 8877's grid.
>
>More nonsense designed to sell magical "kits" .
>
"nonsense", Mr. Rauch? Are gold melt-balls on a cathode and gold
blisters on a grid meaningless?
- According to Mr. Erhorn, the heat-dam problem lasted a bit over a
year. 8877s have been manufactured for roughly 20 years. I have seen
the heat-dam problem in less than 5% of the kaput 8877s I have opened.
It looks to me like the heat-dam issue is a combination of "passing the
buck" and "any port in a storm". . . Meanwhile, back at the avocado
ranch, I find a high percentage of kaput 8874s and 3CX800A7s with
gold-sputtering damage.
There is nothing 'magical' about resistance-wire suppressors. In Wes'
measurements, the improvement (decrease in VHF-Rp) was only 40%
over/under the W8JI suppressor. The resistance-wire suppressor used in
Wes' measurements could have easily been beaten out by a 200nH Ls, made
from silver ribbon, and a 200 ohm Ls. The fly in the ointment was 43
watts of dissipation in Rs on 10m.
R. L. Measures, 805-386-3734, AG6K
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