Cleeve wrote:
>Good morning,
>
> From time to time, I have noted requests for sources of ceramic coil, or
>choke forms......I would draw your attention to an article in the RSGB
>magazine "Radcom" for August 2002, pages 38/39, this is an intersting, and
>practical article, on the home production of such items, by Ted Garrot, G0LMJ.
>
> The technique used is pottery "slip" casting, and photographs of
> finished
>items are included in the article......the only drawback, is that access to a
>kiln is required, to "fire" the finished item, but local potters, or pottery
>classes, might be asked to help.....sincerely, John. G3JVC.
It's certainly very interesting - he has made some very nice plug-in
ceramic coil formers of the good old-fashioned kind.
However, it would be nice to see some results from the microwave-oven
test, in comparison with other materials. I tried that some time ago
with a selection of typical plastics used for RF applications, and also
a "no-name" ceramic coil former. None of the samples got hot or caught
fire, but the material that got warmest was the ceramic!
No doubt there are as many different grades of ceramic as there are of
plastics, each with its own level of RF performance. But I wonder if the
high reputation of "ceramics" in general for RF hasn't been built
largely upon their ability to operate at high temperatures... regardless
of their actual losses?
--
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
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