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Title: Parts Supplier? Post by: WD4KCM on December 10, 2008, 06:53:03 PM Can anyone suggest a source for silver mica caps with tolerances less than 5%? In particular, I am looking for 390 Pfd, 2% (or 1%), 100 volt, for a VFO project. Any source for the mini Teflon coax (without purchasing a roll of 100 feet) would be appreciated. Thanks!
Title: Re: Parts Supplier? Post by: W3NP on December 10, 2008, 08:31:37 PM I recently bought some 500pf and 1000pf 500v mica caps from Mouser. I have gotten both 2% and 5%. At your lower voltage requirement, you may find even more of a selection. No minimum purchase and very reasonable shipping charges.
Title: Re: Parts Supplier? Post by: w3jn on December 12, 2008, 09:46:50 PM Why are you using a 1% capacitor in a VFO circuit? The better way to do it is to parallel a 330 or 360 pF with a NP0 trimmer. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Trust me on this - despite all your calculations, you're gonna hafta trim it some. It's best if the L is adjustable as well as the C - that way you can adjust the range of the VFO. Also use a temp compensating cap - a small N750 in parallel with the coil. |