Werner S. Zielke wrote:
>
> Hi guys,
>
> does any one know about the data's (rf current handling) of the Mica
> Capacitor:
>
> CORNELL DUBILIER, TYPE 9H
> .0004 MFD (400pF),
> WKDV 2500VDC
> TEST 5000VDC
>
> I'm interested how many rf current it can carry. I used four of it in
> parallel with a vary cap together as C2 in the final pi-net of my 75m
> amp using four of 4-1000. Two times one of these caps failures (rf
> power shorts to ground). May be this capacitor is not suitable for rf
> current? Any comments?
>
> 73, Werner DJ2HZ/VE7HBI
>
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Werner, I have suffered similiar failures of other Mica's. What I do now
with my coupling capacitors is test them.
I use 500 watts out from an AMP, series couple it through the coupling
capacitor under test and terminal it in a 50 ohm dummy load. I apply
power and test the temperature of the coupling capacitor after 5 or 10
minutes or evne longer. If it is hot it is having trouble handling 3.3
amps RF.
If you want to use it in a bigger amp. apply 1000 watts as your test
signal and you will be testing the coupling capacitor at 4-5 amps.
You don't want these Mica's blowing during the contest! It scares even
the sleeping!
Regards
Denis VE6AQ
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