Most light alloy cake tins are anodised, so getting consistent contact could be a problem. It's hard to remove the anodising and leave an even surface.. Robert G8RPI.
--- On Sun, 14/3/10, Magnus Danielson <mag...@rubidium.dyndns.org> wrote: From: Magnus Danielson <mag...@rubidium.dyndns.org> Subject: Re: [time-nuts] Choke Ring Pictures To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Date: Sunday, 14 March, 2010, 21:42 Joe Gwinn wrote: >> >> Date: Sun, 14 Mar 2010 21:09:00 +0100 >> From: Magnus Danielson <mag...@rubidium.dyndns.org> >> Subject: Re: [time-nuts] Choke Ring Pictures >> To: Discussion of precise time and frequency measurement >> <time-nuts@febo.com> >> Message-ID: <4b9d425c.2050...@rubidium.dyndns.org> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed >> >> Bob Camp wrote: >>> Hi >>> >>> Wedding cake pans normally come in 1" increments and are either 2" or 3" >>>deep. Sets are 2" increments on the diameter: >>> >>> http://cooksdream.com/store/wedding-round.html >>> >>> >>> http://www.hubert.com/store/products.asp?CAWELAID=126235277&A=SB%2E58369%2E10738&Dn=0&An=966+966&Au=Presentation+Id&Ntt=10738&N=966+966&src=chanadv&Ntx=mode+matchall&D=10738&Ntk=SKU >>> >>> >>> The height would be fairly easy to adjust. The diameter not so much so. >>> >>> Looks like 2 and 2.5" are typical dimensions for the depth. ~1" looks >>>pretty typical for the width. A 2" deep / 2" diameter step set looks like it >>>would do a pretty good job . It won't be accurate enough to be perfect. >>>Without a 3D EM program it would be tough to figure out just what the errors >>>would do to you. >> >> With 2.5" depth and 14", 12", 10", 8" and 6" diameter pans you are not >> completely in a different world from some antennas: >> >> http://facility.unavco.org/project_support/permanent/equipment/antennas/ant_cals.html >> >> >> Evaluating the performance may be a different thing. >> >> One thing to care about is the leakage between the pans if you just stick >> them inside each other. > > I'd be tempted to use EMI gaskets between the pans, except that contact will > soon be lost as the aluminum grows a nice oxide layer. But it may not be > necessary to make DC electrical contact, as the capacitance between the metal > layers may suffice to act as a short at 1.5 GHz. A thin sheet of mylar (or a > heavy anodization layer) between would help this along, by increasing the > capacitance. However it is done, you want it to be fairly stable. Evenly distributed screws against a stable platform like a steel-plate should do it. An alternative is to TIG them together. Cheers, Magnus _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
