On 2/20/2021 10:29 AM, Mark n2qt wrote:
Replacing the micas with Cornell Dubilier CDV style micas helps as those parts
have better specs for RF. I ran rtty contests at 100 watts with no subsequent
failures.
(My problem was always on 15)
The problem with changing or replacing parts in this filter set is that
1) it's very hard to take apart to replace the parts and 2) each filter
in which parts are replaced must be re-aligned with good
instrumentation, AND measurements must made with the enclosure in place
because it affects the filter's tuning. So in practice, you've got to
measure, tweak one or more coils by squeezing or spreading them, put it
back in the enclosure to measure again, repeat, repeat, repeat, repeat
until you get the SWR and transmission loss VERY low in the passband.
The Dunestar filter sets, and the higher priced units that WX0B sells
are FAR superior. The high power VA6AM and 4O3A filters designed to go
on power amp outputs are also excellent.
73, Jim K9YC
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