From: hpsdr-bounces@lists.hpsdr.org on behalf of hpsdr-request@lists.hpsdr.org Sent: Wednesday, April 09, 2008 6:18 PM To: hpsdr@lists.hpsdr.org Subject: Hpsdr Digest, Vol 26, Issue 6 Send Hpsdr mailing list submissions to hpsdr@lists.hpsdr.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org or, via email, send a message with subject or body 'help' to hpsdr-request@lists.hpsdr.org You can reach the person managing the list at hpsdr-owner@lists.hpsdr.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Hpsdr digest..." PLEASE change your subject line in any replies to this digest to reflect the actual subject!!! We all thank you for this thoughtfullness. Today's Topics: 1. Re: Crystal Oscillator for AD9912 (brainerd@wildblue.net) 2. Crystal Packages (Chris Bartram) ---------------------------------------------------------------------- Message: 1 Date: Tue, 08 Apr 2008 16:44:20 -0700 From: brainerd@wildblue.net Subject: Re: [hpsdr] Crystal Oscillator for AD9912 To: hpsdr@hpsdr.org Message-ID: <47FBA0E4.2970.177F865@brainerd.wildblue.net> Content-Type: text/plain; charset="us-ascii" Chris: I am definitely interested in your design. I just got the pre-production boards for my 9912 board. It has provision for either an on-board can oscillator(CMOS, LVDS, or Si57X) as well as an external oscillator input. Also, by an accident in design, the can oscillator output is available via the ext osc input sma. Dave - WB6DHW < > Hello Richard > > As I think you know, I've been working on a very low noise, 10MHz > lockable, 1GHz clock for the AD9912 on behalf of the uWSDR group. To > do it really well is surprisingly non-trivial. The design will also > have implications for other amateur microwave applications. > > My suggestion is that, even if you choose to use a packaged oscillator > or a discrete crystal, you make the 1GHz input accessible via an SMA > connector so that using an external clock module is reasonably easy! > > As to cost, it's still difficult to give an estimate, particularly as > good crystals can cost a lot of money. With a good, but not > exceptional VHF crystal, ordered in 100s I guess that USD30 - USD50 > would cover BOM cost of my design. > > I hope to be able to post the very low noise VHF oscillator design > (uWSDR project DISTAW) which forms the heart of the on the uWSDR web > site in the not too distant future. I'll announce it on the hpsdr list > when I do. > > Vy 73 > > Chris > GW4DGU > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/attachments/20080408/17f8208f/attachment.html ------------------------------ Message: 2 Date: Wed, 9 Apr 2008 01:20:10 +0100 From: Chris Bartram Subject: [hpsdr] Crystal Packages To: hpsdr@lists.hpsdr.org Message-ID: <200804090120.11173.chris@chris-bartram.co.uk> Content-Type: text/plain; charset="iso-8859-1" Amateurs - and a lot of professionals - tend not to specify crystals properly, and manufacturers will only produce what's specified! The HC18/U package was a solder seal package and is now effectively obsolete apart, maybe from when it is used for the lowest quality clock crystals. (Using solder to seal a crystal can is an invitation to excessive ageing...) The package has been replaced by similar packages such as HC49/U using either resistance welding or (better)... cold welding to seal the envelope. The most common packages for VHF crystals are now UM-1 and UM5 or their US military equivalents. These are quite a lot smaller than the old HC18/U package and are are available with cold weld and resistance weld seals. Crystals using in a TO-5 package are also quite common in high-end applications, as the blank can be supported at three points, which makes them a lot less susceptible to vibration-induced problems. There are also ceramic-metal surface-mount packages, but they don't seem to be used for high quality small quantity custom crystals. However, they are quite popular for TCXOs, and a 0.5ppm over -20 to +60C temperature range unit in a 3 x 5mm package is the sort of part I'm currently designing into commercial products. However, the phase noise of these, while OK in the world of ETSI and FCC type approval specs., isn't really good enough for the sort of things that we're trying to do. Vy 73 Chris GW4DGU ------------------------------ _______________________________________________ HPSDR Discussion List To post msg: hpsdr@hpsdr.org Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org HPSDR web page: http://hpsdr.org Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/ End of Hpsdr Digest, Vol 26, Issue 6 ************************************