[Prev][Next][Index][Thread]
Re. Some tests with a 2.25" coil
>Original Poster: "Coiler" <mycroft-at-access1-dot-net>
>
>As some of you know, I have been fighting a few battles with my system -
>one of which is protecting my door opener :)
>
>The other one has been working with my *expletive* capactitor safety gap.
Perhaps you saw my timely post last night about my safety gap experiment,
suggesting the use of large radius gap electrodes? What were the gap
tips like on yours?
>Doing short runs (under 5 seconds) things were fine. Produced anywhere
>from 2-6 14" streamers. After I got things tuned up I let the system run
>for a bit (about 20 seconds) when my cap safety gap started to go nuts.
Sounds identical to my safety gap experiment, where the safety only began
firing after several seconds of operation. I suspect this is due to the
slow accumulation of ionized air between the safety gaps, breaking down
after the concentration gets high enough.
>I checked my main gap, and the pipes were *HOT* (my kids had broken my fan
>plenum - so the air was not ducted to my RQ gap.) So I got curious. I let
>it cool down, and fired up the coil.. things ran fine for about 30
>seconds... then *bang* the safety gap fires.. Again, the gap is hot.
>I am speculating that the poor quenching caused by the overheated gap is
>playing a role in the problems I am seeing with my safety gap, can any of
>you give some additional information in support of or against this idea?
A main gap without good airflow is a terrible performer and gets hot for
two reasons. The obvious one is that there's no forced air flow to cool
it, but the other is that quenching suffers and the duty cycle of main
gap arcing increases greatly. Since the duty cycle of HF across the cap
also increases, the safety gap will generate ionized air more rapidly and
break down more rapidly.
>The only other possiblity (which I have not been able to test yet, wife
>made me shut down because of the noise) is that the new enclosure I built
>for my caps is harboring ionized air from the cap gap.. and that this
>eventually leads to the breakdown.
Sounds right to me.
Gary Lau
Waltham, MA USA