>> Dick Ehrhorn clearly has more experience than I do--
>> but I have used (roughly) more than a 1,000 Eimac
>> oxide-coated cathode type tubes without any issues
>> due to VHF parasitics. Maybe I am just lucky or maybe
>> the design was good. I'll let you decide.
>> Of course this does not cover any Eimac tubes that have
>> had manufacturing problems--such as the heat dam issue
>> for which the 8877s are notorious. (Occasionally Eimac
>> has had brain-flatulence issues with which to contend.)
>> John W0UN
>Everyone else in the world seems to share your and Dick's
/\ The excursion on the wide river in the Land of the Pharoahs
> The only place parasitics cause tube failures is in
>the mind of the fellow who sells kits that "fix the problem".
/\ Have you seen Figure 24 on my Web site? Have you seen the photograph
of the gold-sputtered tube in "Parasitics Revisited" (September/October,
>73, Tom W8JI
/\ A low VHF-Rp parasitic suppressor retrofit-kit never absolutely fixes
the problem. It lowers VHF amplification in HF applications by c. 60%,
and it provides glitch protection just in case a parasite ever takes
place. So far, we have sold more than 5k low VHF-Rp parasitic suppressor
retrofit kits. I keep thinking the market will saturate but it hasn't
thanks to the AL-1500 and other somewhat less than stable HF amplifiers.
Cheers, Mr. Rauch
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
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