Message-ID: <09e901c28971$39cd97c0$0101a8c0@athlon>
From: "Dave Brown" <tractorb@ihug.co.nz>
To: rsgb_lf_group@blacksheep.org
References: <5.1.0.14.0.20021108112020.00aeef28@gemini.herts.ac.uk> <5.1.0.14.0.20021110135548.00a91d88@gemini.herts.ac.uk>
Date: Mon, 11 Nov 2002 23:58:10 +1300
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Subject: Re: LF: To Ponder over the weekend
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Hi Jim

While I have similar reservations there have been a few oil filled tuning
caps used successfully here with tesla coils-not the best parallel to use
but certainly close enough to make the prospect interesting and worth
following up. No problems reported with fires as yet either!
Thee are seemingly very few liquids that are readily available that have
high permittivity, low RF loss and a half decent voltage withstand
capability. Main issue is getting accurate rf loss data at relevant
frequencies.
And what happens to that loss when the voltage applied is raised to the sort
of levels that are needed for this application?
None of the usual info sources carry this sort of detail, so I have not been
able to find very much information on this at all and will be doing some
measurements this summer to prove the usefulness or otherwise of this
technique.
Summer? Well, this is definitely an 'outside in the open air' sort of
activity!!

73
 Dave
ZL3FJ


----- Original Message -----
From: "James Moritz" <j.r.moritz@herts.ac.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, November 11, 2002 3:06 AM
Subject: Re: LF: To Ponder over the weekend


> Dear Dave, LF Group,
>
> At 08:43 09/11/2002 +1300, you wrote:
> >  The neat thing with the oil dielectric is it is basically self healing
,
> >even if it does arc over- no permanent capacitor damage will result as
long
> >as the power is shut off fast enough.. and that's the current issue-no
pun
> >intended!
>
> The un-neat thing about an oil dielectric is its propensity for catching
> fire... also, I don't think it has particularly low loss at RF - although
a
> lot of big TX capacitors are oil-filled, the oil is there to increase the
> breakdown voltage, rather than act as the main dielectric, which is
usually
> mica, I believe.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
>